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• Published: 29 September 2004

Use of animals in experimental research: an ethical dilemma?

• V Baumans 1 , 2  

Gene Therapy volume  11 ,  pages S64–S66 ( 2004 ) Cite this article

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Mankind has been using animals already for a long time for food, for transport and as companion. The use of animals in experimental research parallels the development of medicine, which had its roots in ancient Greece (Aristotle, Hippocrate). With the Cartesian philosophy in the 17th century, experiments on animals could be performed without great moral problems. The discovery of anaesthetics and Darwin's publication on the Origin of Species, defending the biological similarities between man and animal, contributed to the increase of animal experimentation. The increasing demand for high standard animal models together with a critical view on the use of animals led to the development of Laboratory Animal Science in the 1950s with Russell and Burch's three R's of Replacement, Reduction and Refinement as guiding principles, a field that can be defined as a multidisciplinary branch of science, contributing to the quality of animal experiments and to the welfare of laboratory animals. The increased interest in and concern about animal welfare issues led to legislative regulations in many countries and the establishment of animal ethics committees.

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Van Zutphen LFM . History of animal use. In: Van Zutphen LFM, Baumans V, Beynen AC (eds). Principles of Laboratory Animal Science . Elsevier: Amsterdam, 2001, pp 2–5.

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Dennis Jr MB . Welfare issues of genetically modified animals. ILAR J 2002; 43 : 100–109.

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Russell WMS, Burch RL . The Principles of Humane Experimental Technique . Methuen: London, 1959, Reprinted by UFAW, 1992: 8 Hamilton Close, South Mimms, Potters Bar, Herts EN6 3QD England.

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Baumans, V. Use of animals in experimental research: an ethical dilemma?. Gene Ther 11 (Suppl 1), S64–S66 (2004). https://doi.org/10.1038/sj.gt.3302371

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Published : 29 September 2004

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Experimental Moral Philosophy

Experimental moral philosophy emerged as a methodology in the last decade of the twentieth century, as a branch of the larger experimental philosophy (X-Phi) approach. Experimental moral philosophy is the empirical study of moral intuitions, judgments, and behaviors. Like other forms of experimental philosophy, it involves gathering data using experimental methods and using these data to substantiate, undermine, or revise philosophical theories. In this case, the theories in question concern the nature of moral reasoning and judgment; the extent and sources of moral obligations; the nature of a good person and a good life; even the scope and nature of moral theory itself. This entry begins with a brief look at the historical uses of empirical data in moral theory and goes on to ask what, if anything, is distinctive about experimental moral philosophy—how should we distinguish it from related work in empirical moral psychology? After discussing some strategies for answering this question, the entry examines two of the main projects within experimental moral philosophy, and then discusses some of the most prominent areas of research within the field. As we will see, in some cases experimental moral philosophy has opened up new avenues of investigation, while in other cases it has influenced longstanding debates within moral theory.

1.1 What Are Experiments?

1.2 what types of questions and data, 2.1 the negative program in experimental moral philosophy, 2.2 the positive program in experimental moral philosophy, 2.3 an example: intentionality and responsibility, 2.4 another example: the linguistic analogy, 2.5 cross-cultural experimental moral philosophy, 3.1 character and virtue, 3.2 wellbeing, happiness, and the good life, 3.3 emotion and affect, 3.4 moral standing, 4.1 folk metaethics and moral realism, 4.2 moral disagreement, 4.3 moral language, 5.1 problems with experimental design and interpretation, 5.2 philosophical problems, other internet resources, related entries, 1. introduction and history.

The idea that our actual moral judgments are an important source of information about the origins and justification of moral norms goes back to ancient Greece, if not further. Herodotus recounts a story in which the Persian emperor Darius invited Greek members of his court “and asked them what price would persuade them to eat the dead bodies of their fathers. They answered that there was no price for which they would do it.” Darius then summoned members of a different group, “and asked them… what would make them willing to burn their fathers at death. The Indians cried aloud, that he should not speak of so horrid an act.” Herodotus concludes that stories like these prove that, as the poet Pindar writes, “custom is king of all,” thereby providing an instance of the argument from moral disagreement for relativism. Likewise, in the Outlines of Skepticism , Sextus Empiricus stresses that empirical discoveries can destabilize our confidence in universal moral agreement:

even if in some cases we cannot see an anomaly, we should say that possibly there is dispute about these matters too… Just as, if we had not, for example, known about the Egyptian custom of marrying their sisters, we should have affirmed, wrongly, that it is agreed by all that you must not marry your sister. (Sextus Empiricus, Outlines of Skepticism )

While the use of empirical observation in moral theory has a long history, the contemporary movement known as experimental philosophy goes back only a few decades. The current experimental philosophy movement owes its beginnings to the work of Stephen Stich, Shaun Nichols and Jonathan Weinberg (2001) and Joshua Knobe (2003), but the earliest instance of experimental philosophy may be Truth as Conceived by Those Who Are Not Professional Philosophers (Naess 1938), which surveyed ordinary speakers for their intuitions about the nature of truth. Contemporary philosophers have not been uniformly accepting of the movement, but as we will see, there are reasons to think that experimental evidence might have a distinctive role, significance, and importance in moral philosophy and theorizing.

The relationship between more traditional philosophy and experimental work is instructive and brings out some tensions within moral philosophy and theory: namely, morality is at once practical and normative, and these two aspects inform and constrain the extent to which it is accountable to human psychology.

Insofar as morality is practical, it should be accessible to and attainable by agents like us: if a theory is too demanding, or relies on intuitions, judgments, motivations, or capacities that people do not (or, worse, cannot) possess, we might on those grounds dismiss it. On the other hand, morality is also normative: it aims not just to describe what we actually do or think, but to guide our practice. For this reason, some philosophers have responded to experimental results claiming to show that attaining and reliably expressing virtues in a wide variety of situations is difficult (see section 3.1 below for a discussion of this literature) by pointing out that the fact that people do not always make the right judgment, or perform actions for the right reasons, does not falsify a theory—it simply shows that people often act in ways that are morally deficient. We will return to these issues when we discuss criticisms of experimental moral philosophy at the end of this entry; for now, we mention them to illustrate that the extent to which experimental moral philosophy challenges traditional philosophical approaches is itself a controversial issue. Some moral philosophers see themselves as deriving moral principles a priori, without appeal to contingent facts about human psychology. Others see themselves as working within a tradition, going back at least as far as Aristotle, that conceives of ethics as the study of human flourishing. These philosophers have not necessarily embraced experimental moral philosophy, but many practitioners envision their projects as outgrowths of the naturalistic moral theories developed by Aristotle, Hume, and others.

As the examples discussed above reveal, a variety of types of empirical evidence are useful to moral theorizing (see also the entries on empirical moral psychology, empirical distributive justice, and empirical psychology and character). Anthropological observation and data have long played a role in moral philosophy. The twentieth-century moral philosophers John Ladd and Richard Brandt investigated moral relativism in part by conducting their own ethnographies in Native American communities. Brandt writes, “We have… a question affecting the truth of ethical relativism which, conceivably, anthropology can help us settle. Does ethnological evidence support the view that ”qualified persons“ can disagree in ethical attitude?” But, he notes, “some kinds of anthropological material will not help us—in particular, bare information about intercultural differences in ethical opinion or attitude.” (1952: 238). This is a caveat frequently cited by philosophers engaged in empirical research: it is important to have philosophers participate in experimental design and the gathering of empirical data, because there are certain questions that must be addressed for the data to have philosophical applications—in this case, whether moral disagreements involve different factual beliefs or other non-moral differences. Barry Hallen (1986, 2000) conducted a series of interviews and ethnographies among the Yoruba, investigating central evaluative concepts and language relating to epistemology, aesthetics, and moral value. Hallen was motivated by questions about the indeterminacy of translation, but his work provides an example of how in-depth interviews can inform investigations of philosophical concepts.

These examples show that ethnography has a valuable role to play in philosophical theory, but the remainder of this entry will focus primarily on experiments. Paradigmatic experiments involve randomized assignment to varying conditions of objects or people from a random sample, followed by statistical comparison of the outcomes for each condition. The variation in conditions is sometimes called a manipulation. For example, an experimenter might select a random sample of people, randomly assign them either to find or not to find a dime in the coin return of a pay phone, and then measure the degree to which they subsequently help someone they take to be in need (Isen & Levin 1972). Finding or not finding the dime is the condition; degree of helpfulness is the outcome variable.

While true experiments follow this procedure, other types of studies allow non-random assignment to conditions. Astronomers, for example, sometimes speak of natural experiments. Although we are in no position to affect the motions of heavenly bodies, we can observe them under a variety of conditions, over long periods of time, and with a variety of instruments. Likewise, anthropological investigation of different cultures’ moral beliefs and practices is unlikely to involve manipulating variables in the lives of the members of the culture, but such studies are valuable and empirically respectable. Still, inferring causation is more difficult with such studies, so the evidential value of these studies is often less than that of experiments, at least in this respect; most published research in experimental philosophy involves true experiments.

Even within the category of experiments, we find a lot of diversity with respect to inputs, methods of measurement, and outputs. The experiment just described uses a behavioral measure and manipulation—finding the dime is the input, helping is the outcome measured. Other experiments measure not behavior but judgment or intuition, and this can be done using a survey or other form of self–report or informant–report where subjects respond explicitly to some question, situation, or dilemma. Studies measuring judgments might use either manipulations of the condition in which the subject makes the judgment, or they might look for correlations between judgments and some other factor, such as brain activity, emotional response, reaction time, visual attention, and so on (Strohminger et al. 2014).

The experimental methods available have also changed over time. Surveys have been the dominant method of experimental philosophy for the past few decades, but technology may change this: advances in virtual and augmented reality mean that philosophers can now immerse people in moral dilemmas such as Thompson’s (1971) violinist thought experiment and different versions of the trolley problem (e.g., Navarrete et al 2012). Philosophers interested in the neural correlates of moral judgment can use transcranial magnetic stimulation (TMS) to investigate the effects of enhancing or lessening activity in certain areas of the brain. Even survey methods have seen advances thanks to technology; the ubiquity of smartphones allows researchers to ping people in real time, asking for reports on mood (see section 3.2 below for a discussion of surveys relating to happiness and mood).

Whether experimental moral philosophy has to use true experiments or can include studies and even ethnographies and other forms of qualitative data is partly a terminological question about how to define the field and whether we distinguish it from empirical moral psychology, a closely related research program. As we will see below, though, a diversity of both methods and subjects is important in helping experimental moral philosophy respond to its critics.

Like experimental philosophy more generally, experimental moral philosophy is interested in our intuitions and judgments about philosophical thought experiments and moral dilemmas. But research in this area also concerns the cognitive architecture underlying our moral judgments; the developmental processes that give rise to moral judgments; the neuroscience of moral judgment; and other related fields.

Direct experiments investigate whether a claim held (or denied) by philosophers is corroborated or falsified. This might mean investigating an intuition and whether it is as widely shared as philosophers claim, or it might mean investigating the claim that a certain behavior or trait is widespread or that two factors covary. For example, we find philosophers claiming that it is wrong to imprison an innocent person to prevent rioting; that a good life must be authentic; and that moral judgments are intrinsically motivating. Experimental research can be (and has been, as we will see below) brought to bear on each of these claims.

Indirect experiments look at the nature of some capacity or judgment: for example, whether certain types of moral dilemmas engage particular areas of the brain; how early children develop a capacity to empathize; and whether the moral/conventional distinction is universal across cultures (for discussion of the moral/conventional distinction, see Machery & Stich 2022). These claims have philosophical relevance insofar as they help us understand the nature of moral judgment.

In addition to distinctions involving the type of data and how directly it bears on the question, we can also distinguish among experimental applied ethics, experimental normative ethics, and experimental metaethics. The first involves the variables that influence judgments about particular practical problems, such as how a self-driving car should respond to sacrificial dilemmas (Bonnefon, Sharriff & Rahwan 2016). The second involves investigations of how we ought to behave, act, and judge, as well as our intuitions about moral responsibility, character, and what constitutes a good life. The third involves debates over moral realism and antirealism. In this entry we focus on the latter two.

In many of these cases, the line between experimental moral philosophy and its neighbors is difficult to draw: what distinguishes experimental moral philosophy from empirical moral psychology? What is the difference between experimental moral philosophy and psychology or neuroscience that investigates morality? What is the difference between experimental moral philosophy and metaethics? We might try to answer these questions by pointing to the training of the experimenters—as philosophers or as scientists—but much of the work in these areas is done by collaborative teams involving both philosophers and social scientists or neuroscientists. In addition, some philosophers work in law and psychology departments, and graduate programs increasingly offer cross-disciplinary training. Another approach would be to look at the literature with which the work engages: many psychologists (e.g., Haidt, Greene) investigating moral judgment situate their arguments within the debate between Kantians and Humeans, so engagement with the philosophical tradition might be used as a criterion to distinguish experimental moral philosophy from experimental moral psychology. All this said, an inability to sharply distinguish experimental moral philosophy from adjoining areas of investigation may not be particularly important. Experimental philosophers often point out that the disciplinary divide between philosophy and psychology is a relatively recent phenomenon; early twentieth-century writers such as William James situated themselves in both disciplines, making vital contributions to each. If there is a problem here, it is not unique to experimental moral philosophy. For example, is work on semantics that uses both linguistics and analytic philosophy best understood as linguistics or philosophy of language? These debates arise, and may be largely moot, for many research programs that cut across disciplinary boundaries.

The rest of this entry proceeds as follows. Section 2 canvasses experimental research on moral judgments and intuitions, describing various programmatic uses to which experimental results have been put, then turning to examples of experimental research on moral judgment and intuition, including intuitions about intentionality and responsibility, the so-called linguistic analogy, and some cross-cultural work. Section 3 discusses experimental results on thick (i.e., simultaneously descriptive and normative) topics, including character and virtue, well-being, emotion and affect, and moral standing. Section 4 discusses questions about moral disagreement and moral language, both important sources of evidence in the longstanding debate over moral objectivity. Section 5 considers some objections to experimental moral philosophy.

2. Moral Intuitions and Conceptual Analysis

One role for experiments in moral philosophy, as indicated above, is to investigate our moral intuitions about cases, and to use the results gleaned from such investigations to guide or constrain our moral metaphysics, semantics, or epistemology. Philosophers often rely on such judgments—in the form of claims to the effect that “we would judge x” or, “intuitively, x”—as data or evidence for a theory (though see Cappelen 2012, Deutsch 2016, and Machery 2017 for critical discussion of this point). Claims about what we would judge or about the intuitive response to a case are empirically testable, and one project in experimental moral philosophy (perhaps the dominant original project) has been to test such claims via an investigation of our intuitions and related moral judgments. In doing so, experimental moral philosophers can accomplish one of two things: first, they can test the claims of traditional philosophers about what is or is not intuitive; second, they can investigate the sources of our intuitions and judgments. These tasks can be undertaken as part of a positive program, which uses our intuitions and judgments as inputs and constructs theories that accommodate and explain them. Alternatively, these tasks can figure in a negative program, which uses experimental research to undermine traditional appeals to intuition as evidence in moral philosophy and conceptual analysis more broadly. The negative program can proceed directly or indirectly: either via testing and refuting claims about intuitions themselves, or by discrediting the sources of those intuitions by discovering that they are influenced by factors widely regarded as not evidential or unreliable. We discuss both the negative program and the positive program below.

Early work in experimental philosophy suggested cross-cultural differences in semantic, epistemic, and moral intuitions. For example, Machery, Mallon, Nichols, and Stich (2004) argued that East Asian subjects were more likely to hold descriptivist intuitions than their Western counterparts, who tended to embrace causal theories of reference. Haidt (2006) argued that the extent to which people judged harmless violations such as eating a deceased pet, or engaging in consensual sibling incest, to be wrong depended on socioeconomic status. Since, presumably, moral wrongness doesn’t itself depend on socioeconomic status, gender, or culture of the person making the moral judgment, these results have been marshaled to argue either against the evidential value of intuitions or against the existence of moral facts altogether.

Negative experimental moral philosophy generates results that are then used to discount the evidential value of appeals to intuition (for review, Machery 2017, Chapter 2). For example, Singer (2005), Sinnott-Armstrong (2008d), Lanteri and colleagues (2008), Lombrozo (2009), Schwitzgebel and Cushman (2012, 2015), Liao and colleagues (2012), Tobia and colleagues (2013), Wiegmann and colleagues (2020), Rehren and Walter (2021), and McDonald et al. (2021) have argued that moral intuitions are subject to normatively irrelevant situational influences (e.g., order or framing effects), while Feltz and Cokely (2009) and Knobe (2011) have documented correlations between moral intuitions and (presumably) normatively irrelevant individual differences (e.g., extroversion). Such results might warrant skepticism about moral intuitions, or at least about some classes of intuitions or intuiters. [ 1 ]

The studies just mentioned involve results that suggest that the content of intuitions varies along some normatively irrelevant dimension. Another source of evidence for the negative program draws on results regarding the cognitive mechanisms underlying or generating intuitions themselves. For example, studies that suggest that deontological intuitions are driven by emotional aversions to harming others have been used to argue that we ought to discount our deontological intuitions in favor of consequentialist principles—an idea discussed in more detail below (see Singer 2005; Wiegman 2017). In several experiments, Kneer and Machery (2019) show that judgments about moral luck result from the hindsight bias, i.e., the tendency to overestimate the probability that events known to have happened would happen. Thus, the probability that the unlucky event in a bad luck situation (e.g., a car accident involving a drunk driver) would happen is overestimated and the agent is judged to have been more negligent than her counterpart in a lucky situation (the drunk driver who did not get into any accident). This psychological account is then used to undermine the philosophical significance of intuitions about moral luck: If the asymmetry between good and back luck situations is due to a psychological bias, it should not bear on philosophical theorizing.

The distinction between negative and positive experimental moral philosophy is difficult to draw, partly because the negative program often discounts particular classes or types of intuitions in favor of others that are supposed to be more reliable. For example, Singer offers an anti-deontological argument as part of the negative program insofar as his argument uses the emotional origins of deontological intuitions to discount them. But because he then argues for the superiority of consequentialist intuitions, his position also fits within the positive program. So the difference between the two programs is not in the data or the kinds of questions investigated, but in how the data are put to use—whether they are seen as debunking traditional philosophical appeals to intuition or as an addition to traditional philosophical appeals to intuition, by helping philosophers distinguish between reliable and unreliable intuitions and their sources. In the next section, we look at positive uses of intuitions as evidence.

Other philosophers are more sanguine about the upshot of experimental investigations of moral judgment and intuition. Knobe, for example, uses experimental investigations of the determinants of moral judgments to identify the contours of philosophically resonant concepts and the mechanisms or processes that underlie moral judgment. He has argued for the pervasive influence of moral considerations throughout folk psychological concepts (2009, 2010; see also Pettit & Knobe 2009), claiming, among other things, that the concept of an intentional action is sensitive to the foreseeable evaluative valence of the consequences of that action (2003, 2004b, 2006). [ 2 ]

Another line of research is due to Joshua Greene and his colleagues (Greene et al. 2001, 2004, 2008; Greene 2008), who investigate the neural bases of consequentialist and deontological moral judgments (but see Kahane et al. 2015). Greene and his colleagues elicited the intuitions of subjects about a variety of trolley problems—cases that present a dilemma in which a trolley is racing towards five individuals, all of whom will be killed unless the trolley is instead diverted towards one individual—while inside an fMRI scanner. The researchers found that, when given cases in which the trolley is diverted by pulling a switch, most subjects agreed that diverting the trolley away from the five and towards the one person was the right action. When, instead, the case involved pushing a person off a bridge to land in front of and halt the trolley, subjects were less likely to judge that sacrificing the one person as morally permissible. In addition, Greene found that subjects who did judge it permissible to push the person took longer to arrive at their judgment, suggesting that they had to overcome conflicting intuitions to do so (but see McGuire et al. 2009)—a finding bolstered by the fact that when subjects considered pushing the person off the bridge, their brains revealed increased activity in areas associated with the aggregation and modulation of value signals (e.g., ventromedial prefrontal cortex and dorsolateral prefrontal cortex). Greene concludes that our aversion to pushing the person is due to an emotional response to the thought of causing physical harm to someone, while our willingness to pull the switch is due to the rational calculation that saving five people is preferable to letting five people die to spare one life. Greene and Singer use these findings as a basis for a debunking of deontological intuitions and a vindication of consequentialism, since the latter rests on intuitions which stem from a source we consider both generally reliable and appropriately used as the basis for moral reasoning. It should be noted, though, that this argument presupposes that emotional reactions are (at least in these cases) necessarily irrational or arational; philosophers who are unsympathetic to such a view of emotions need not follow Greene and Singer to their ultimate conclusions (Berker 2009; Greene 2014; Railton 2014).

A related approach aims to identify the features to which intuitions about philosophically important concepts are sensitive. Sripada (2011) thinks that the proper role of experimental investigations of moral intuitions is not to identify the mechanisms underlying moral intuitions. Such knowledge, it is claimed, contributes little of relevance to philosophical theorizing. It is rather to investigate, on a case by case basis, the features to which people are responding when they have such intuitions. On this view, people (philosophers included) can readily identify whether they have a given intuition, but not why they have it. An example from the debate over determinism and free will: manipulation cases have been thought to undermine compatibilist intuitions—intuition supporting the notion that determinism is compatible with “the sort of free will required for moral responsibility” (Pereboom 2001). In such cases, an unwitting victim is described as having been surreptitiously manipulated into having and reflectively endorsing a motivation to perform some action. Critics of compatibilism say that such cases satisfy compatibilist criteria for moral responsibility, and yet, intuitively, the actors are not morally responsible (Pereboom 2001). Sripada (2011) makes a strong case, however, through both mediation analysis and structural equation modeling, that to the extent that people feel the manipulee not to be morally responsible, they do so because they judge him in fact not to satisfy the compatibilist criteria. [ 3 ] Thus, by determining which aspects of the case philosophical intuitions are responding to, it might be possible to resolve otherwise intractable questions.

Since Knobe’s seminal (2003) paper, experimental philosophers have investigated the complex patterns in people’s dispositions to make judgments about moral notions (praiseworthiness, blameworthiness, responsibility), cognitive attitudes (belief, knowledge, remembering), motivational attitudes (desire, favor, advocacy), and character traits (compassion, callousness) in the context of violations of and conformity to various norms (moral, prudential, aesthetic, legal, conventional, descriptive). [ 4 ] In Knobe’s original experiment, participants first read a description of a choice scenario: the protagonist is presented with a potential policy (aimed at increasing profits) that would result in a side effect (either harming or helping the environment). Next, the protagonist explicitly disavows caring about the side effect, and chooses to go ahead with the policy. The policy results as advertised: both the primary and the side effect occur. Participants are asked to attribute intentionality or an attitude (or, in the case of later work by Robinson et al. 2013, a character trait) to the protagonist. What Knobe found was that participants were significantly more inclined to indicate that the protagonist had intentionally brought about the side effect when it was perceived to be bad (harming the environment) than when it was perceived to be good (helping the environment). This effect has been replicated dozens of times, and its scope has been greatly expanded from intentionality attributions after violations of a moral norm to attributions of diverse properties after violations of a wide variety of norms.

The first-order aim of interpreters of this body of evidence is to create a model that predicts when the attribution asymmetry will crop up. The second-order aims are to explain as systematically as possible why the effect occurs, and to determine the extent to which the attribution asymmetry can be considered rational. Figure 1, presented here for the first time, models how participants’ responses to this sort of vignette are produced (for a different, neuroscientific approach, see Ngo et al. 2015):

Figure 1. Model of Participant Response to Experimental Philosophy Vignettes

In this model, the boxes represent constructs, the arrows represent causal or functional influences, and the area in grey represents the mind of the participant, which is not directly observable but is the target of investigation. In broad strokes, the idea is that a participant first reads the text of the vignette and forms a mental model of what happens in the story. On the basis of this model (and almost certainly while the vignette is still being read), the participant begins to interpret, i.e., to make both descriptive and normative judgments about the scenario, especially about the mental states and character traits of the people in it. The participant then reads the experimenter’s question, forms a mental model of what is being asked, and—based on her judgments about the scenario—forms an answer to that question. That answer may then be pragmatically revised (to avoid unwanted implications, to bring it more into accord with what the participant thinks the experimenter wants to hear, etc.) and is finally recorded as an explicit response to a statement about the protagonist’s attitudes (e.g., “he brought about the side effect intentionally,” graded on a Likert scale). [ 5 ]

A result that has been replicated repeatedly is that, when the vignette describes a norm violation, subjects indicate that they agree more strongly that the action violating the norm was performed intentionally. While this finding could be used by proponents of the negative program to undermine the conceptual coherence of our notion of moral responsibility, experimental moral philosophers working in the positive program have taken up the task of explaining the asymmetry by postulating models of unobservable entities that mediate, explain, and perhaps even rationalize the asymmetry. A discussion of several attempts to do so follows; each offers a different explanation of the asymmetry, but all represent vindications or at least rehabilitations of our intuitions about intention.

The Conceptual Competence Model

Perhaps the best known is Knobe’s conceptual competence model, according to which the asymmetry arises at the judgment stage. On this view, normative judgments about the action influence otherwise descriptive judgments about whether it was intentional (or desired, or expected, etc.). Moreover, this influence is taken to be part of the very conception of intentionality (desire, belief, etc.). Thus, on the conceptual competence model, the asymmetry in attributions is a rational expression of the ordinary conception of intentionality (desire, belief, etc.), which turns out to have a normative component (see Machery 2008 for doubts about how to circumscribe what is part of the conceptual competence with any given concept). [ 6 ]

The Motivational Bias Model

The motivational bias model (Alicke 2008; Nadelhoffer 2004, 2006) agrees that the asymmetry originates in the judgment stage, and that normative judgments influence descriptive judgments. However, unlike the conceptual competence model, it takes this to be a bias rather than an expression of conceptual competence. Thus, on this model, the asymmetry in attributions is a distortion of the correct conception of intentionality (desire, belief, etc.).

The Deep Self Model

The deep self concordance model (Sripada 2010, 2012; Sripada & Konrath 2011) also locates the source of the asymmetry in the judgment stage, but does not recognize an influence (licit or illicit) of normative judgments on descriptive judgments. Instead, proponents of this model claim that when assessing intentional action, people not only attend to their representation of a person’s “surface” self—her expectations, means-end beliefs, moment-to-moment intentions, and conditional desires—but also to their representation of the person’s “deep” self, which harbors her sentiments, values, and core principles (for critical discussion, see Rose et al. 2012). According to this model, when assessing whether someone intentionally brings about some state of affairs, people determine (typically unconsciously) whether there exists sufficient concordance between their representation of the outcome the agent brings about and what they take to be her deep self. For instance, when the chairman says he does not care at all about either harming or helping the environment, people attribute to him a deeply anti-environment stance. When he harms the environment, this is concordant with his anti-environment deep self; in contrast, when the chairman helps the environment, this is discordant with his anti-environment deep self. According to the deep self concordance model, then, the asymmetry in attributions is a reasonable expression of the folk psychological distinction between the deep and shallow self.

The Conversational Pragmatics Model

Unlike the models discussed so far, the conversational pragmatics model (Adams & Steadman 2004, 2007; Lindauer & Southwood 2021) locates the source of the asymmetry in the pragmatic revision stage. According to this model, participants judge the protagonist not to have acted intentionally in both norm-conforming and norm-violating cases. However, when it comes time to tell the experimenter what they think, participants do not want to be taken as suggesting that the harm-causing protagonist is blameless, so they report that he acted intentionally. This is a reasonable goal, so according to the pragmatic revision model, the attribution asymmetry is rational, though misleading.

The Trade-Off Model

The trade-off model (Machery 2008) disagrees with the previous models about the location of the source of the asymmetry: it locates it in the interpretation of the scenario. It proposes that when people read that the chairman agrees to harm the environment, they conceptualize the side effect harming the environment as a cost, that is, as something that is negatively valued and that one must incur if one is to reap a greater benefit. People think of this cost as being offset by the benefit increasing the profits of the company . That is, they conceptualize the harm case as involving a trade-off between a cost and a benefit. The side effect helping the environment cannot be conceptualized in this way since it cannot be plausibly thought of as a cost. Since people think of costs as being intentionally incurred in order to reap some foreseen benefits, the side effect is judged to be intentional in the former situation, but not in the latter situation.

The Deliberation Model

Like the trade-off model, according to the deliberation model (Alfano, Beebe, & Robinson 2012; Robinson, Stey, & Alfano 2013; Scaife & Webber 2013), the best explanation of the complex patterns of evidence is that the very first mental stage, the formation of a mental model of the scenario, differs between norm-violation and norm-conformity vignettes. When the protagonist is told that a policy he would ordinarily want to pursue violates a norm, he acquires a reason to deliberate further about what to do; in contrast, when the protagonist is told that the policy conforms to some norm, he acquires no such reason. Participants tend to think of the protagonist as deliberating about what to do when and only when a norm would be violated. Since deliberation leads to the formation of other mental states such as beliefs, desires, and intentions, this basal difference between participants’ models of what happens in the story flows through the rest of their interpretation and leads to the attribution asymmetry. On the deliberation model, then, the attribution asymmetry originates earlier than other experimental philosophers suppose, and is due to rational processes.

Another positive program investigates the structure and form of moral intuitions, in addition to their content, with the aim of using these features to inform a theory of the cognitive structures underlying moral judgment and their etiology.

Rawls (1971), drawing on Chomsky’s (1965) theory of generative linguistics, suggested that moral cognition might be usefully modeled on our language faculty, a parallel endorsed by Chomsky himself:

I don’t doubt that we have a natural moral sense….That is, just as people somehow can construct an extraordinarily rich system of knowledge of language on the basis of rather limited and degenerate experience, similarly, people develop implicit systems of moral evaluation, which are more or less uniform from person to person. There are differences, and the differences are interesting, but over quite a substantial range we tend to make comparable judgments, and we do it, it would appear, in quite intricate and delicate ways involving new cases and agreement often about new cases… and we do this on the basis of a very limited environmental context available to us. The child or the adult doesn’t have much information that enables the mature person to construct a moral system that will in fact apply to a rich range of cases, and yet that happens.…whenever we see a very rich, intricate system developing in a more or less uniform way on the basis of rather restricted stimulus conditions, we have to assume that there is a very powerful, very rich, highly structured innate component that is operating in such a way as to create that highly specific system on the basis of the limited data available to it. (Chomsky, quoted in Mikhail 2005).

Here Chomsky points to four similarities between the development of linguistic knowledge and the development of moral knowledge:

L1: A child raised in a particular linguistic community almost inevitably ends up speaking an idiolect of the local language despite lack of sufficient explicit instruction, lack of extensive negative feedback for mistakes, and grammatical mistakes by caretakers. M1: A child raised in a particular moral community almost inevitably ends up judging in accordance with an idiolect of the local moral code despite lack of sufficient explicit instruction, lack of sufficient negative feedback for moral mistakes, and moral mistakes by caretakers. L2: While there is great diversity among natural languages, there are systematic constraints on possible natural languages. M2: While there is great diversity among natural moralities, there are systematic constraints on possible natural moralities. L3: Language-speakers obey many esoteric rules that they themselves typically cannot articulate or explain, and which some would not even recognize. M3: Moral agents judge according to esoteric rules (such as the doctrine of double effect) that they themselves typically cannot articulate or explain, and which some would not even recognize. L4: Drawing on a limited vocabulary, a speaker can both produce and comprehend a potential infinity of linguistic expressions. M4: Drawing on a limited moral vocabulary, an agent can produce and evaluate a very large (though perhaps not infinite) class of action-plans, which are ripe for moral judgment.

We will now explain and evaluate each of these pairs of claims in turn.

L1/M1 refer to Chomsky’s poverty of the stimulus argument: despite receiving little explicit linguistic and grammatical instruction, children develop language rapidly and at a young age, and quickly come to display competence applying complex grammatical rules. Similarly, Mikhail and other proponents of the analogy argue that children acquire moral knowledge at a young age based on relatively little explicit instruction. However, critics of the analogy point out several points of difference. First, children actually receive quite a bit of explicit moral instruction and correction, and in contrast with the linguistic case, this often takes the form of explicit statements of moral rules: ‘don’t hit,’ ‘share,’ and so on. Secondly, there is debate over the age at which children actually display moral competence. Paul Bloom (2013; see also Blake, McAuliffe, and Warneken 2014) has argued that babies display moral tendencies as early as 3–6 months, but others (most famously Kohlberg (1969) and Piaget (1970)) have argued that children are not fully competent with moral judgment until as late as 8–12 years, by which time they have received quite a bit of moral instruction, both implicit and explicit. A related point concerns the ability to receive instructions: in the case of language, a child requires some linguistic knowledge or understanding in order even to receive instruction: a child who has no understanding of language will not understand instructions given to her. But in the moral case, a child need not understand moral rules in order to be instructed in them, so there is less need to posit some innate knowledge or understanding. Nichols et al. (2016) have conducted a series of experiments using statistical learning and Bayesian modeling to show how children might learn complex rules with scant input (see also Nichols 2021). Finally, while children may initially acquire the moral values present in their environment, they sometimes change their values or develop their own values later in life in ways that present spontaneously and with little conscious effort. This is in marked contrast with language; as any second-language learner will recognize, acquiring a new language later in life is effortful and, even if one succeeds in achieving fluency, the first language is rarely lost. Lastly, as Prinz (2008) points out, children are punished for moral violations, which may explain why they are quicker to learn moral than grammatical rules.

L2/M2 refer to the existence of so-called linguistic universals : structures present in all known languages. Whether this is true in the moral case is controversial, for reasons we’ll discuss further below. Prinz (2008) and Sripada (2004) have argued that there are no exceptionless moral universals, unless one phrases or describes the norms in question in such a way as to render them vacuous. Sripada uses the example ‘murder is wrong’ as a vacuous rule: while this might seem like a plausible candidate for a moral universal, when we consider that ‘murder’ refers to a wrongful act of killing, we can see that the norm is not informative. But Mikhail might respond by claiming that the fact that all cultures recognize a subset of intentional killings as morally wrong, even if they differ in how they circumscribe this subset, is itself significant, and the relevant analogy here would be with the existence of categories like ‘subject’, ‘verb’, and ‘object’ in all languages, or with features like recursion, which are present in the grammars of all natural languages (but see Everett 2005).

L3/M3 refer to the patterns displayed by grammatical and moral intuitions. In the case of language, native speakers can recognize grammatical and ungrammatical constructions relatively easily, but typically cannot articulate the rules underlying these intuitions. In the case of moral grammar, the analogy claims, the same is true: we produce moral intuitions effortlessly without being able to explain the rules underlying them. Indeed, in both cases, the rules underlying the judgments might be quite esoteric and difficult for native speakers to learn and understand.

L4/M4 refer to the fact that we can embed linguistic phrases within other linguistic phrases to create novel and increasingly complex phrases and sentences. This property is known as recursion , and is present in all known natural languages (indeed, Chomsky suggests that perhaps recursion is the only linguistic universal; see Hauser, Chomsky & Fitch 2002; but see Everett 2005). For instance, just as phrases can be embedded in other phrases to form more complex phrases:

the calico cat \(\rightarrow\) the calico cat (that the dog chased) \(\rightarrow\) the calico cat (that the dog [that the breeding conglomerate wanted] chased) \(\rightarrow\) the calico cat (that the dog [that the breeding conglomerate{that was bankrupt} wanted] chased)

so the descriptions of actions that are morally assessed can be embedded in other action descriptions to produce novel action descriptions (Harman 2008, 346). For example:

It’s wrong to \(x \rightarrow\) It’s wrong to coerce someone to \(x \rightarrow\) It’s wrong to persuade someone to coerce someone to \(x\).

The point is twofold: first, we can create complex action descriptions; second, we can evaluate novel and complex actions and respond with relatively automatic intuitions of grammatical or moral permissibility.

Mikhail (2011: 43–48) uses experimental evidence of judgments about trolley problems to argue that our moral judgments are generated by imposing a deontic structure on our representation of the causal and evaluative features of the action under consideration. Mikhail points to a variation on the poverty of the stimulus argument, which he calls the poverty of the perceptual stimulus (Mikhail 2009: 37): when faced with a particular moral situation, we draw complex inferences about both act and actor based on relatively little data. Mikhail (2010) uses this argument against models of moral judgment as affect-driven intuitions:

Although each of these rapid, intuitive, and highly automatic moral judgments is occasioned by an identifiable stimulus, how the brain goes about interpreting these complex action descriptions and assigning a deontic status to each of them is not something revealed in any obvious way by the surface structure of the stimulus itself. Instead, an intervening step must be postulated: an intuitive appraisal of some sort that is imposed on the stimulus prior to any deontic response to it. Hence, a simple perceptual model, such as the one implicit in Haidt’s (2001) influential model of moral judgment, appears inadequate for explaining these intuitions, a point that can be illustrated by calling attention to the unanalyzed link between eliciting situation and intuitive response in Haidt’s model

Unlike the traditional poverty of the stimulus argument, this version does not rely on developmental evidence, but on our ability to quickly and effortlessly appraise complicated scenarios, such as variations on trolley problems, in a way that is independent of their superficial features (e.g., the way they are described), and then issue normative judgments. The postulated intervening step is like the unconscious appeal to rules of grammar, and the evidence for such a step must come from experiments showing that we do, in fact, have such intuitions, and that they conform to predictable patterns.

The linguistic analogy relies on experimental evidence about the nature and pattern of our moral intuitions, and it outlines an important role for experiments in moral theory. If the analogy holds, then a descriptively adequate moral theory must be based on the judgments of competent moral judges (although a reformist moral theory need not, or at least not to the same extent), just as grammatical rules are constructed based on the judgments of competent speakers. A pressing task will be the systematic collection of such judgments. The analogy also suggests a kind of rationalism about moral judgment, since it posits that our judgments result from the unconscious application of rules to cases. Finally, the analogy might have metaethical implications. Just as we can only evaluate grammaticality of utterances relative to a language, it may be that we can only evaluate the morality of an action relative to a specific moral system. How to individuate moralities, and how many (assuming there are multiple ones) there are, is a question for further empirical investigation, and here again experimental evidence will play a crucial role.

Guided by the idea that variation in some judgments might challenge our trust in them (Machery 2017, Chapter 4), the negative program has led experimental philosophers to examine whether moral judgments vary across cultures and other demographic groups (see also Graham et al. 2016; Doris et al. 2020). Early research focused on the distinction between causing harm as a means or as a side effect, and failed to find any cultural variation using the footbridge and the bystander versions of the trolley case (Hauser et al. 2007; Moore et al. 2011), but a few articles have observed differences among Americans, Russians and Chinese (Ahlenius & Tännsjö 2012), English and Chinese (Gold et al. 2014), and Yali horticulturalists in Papua (Sorokowski et al. 2020). A recent study of moral judgments in 45 countries found that people find it less acceptable to cause someone’s death as a means to prevent a greater harm than as a mere side effect; they also find it less acceptable to cause someone’s death as a means to prevent a greater harm when the death results from “personal force”, i.e., when the force that impacts the victim originates in the agent’s muscles; but the interaction between these two factors, which had been observed in the USA, was only found in Western countries (Bago et al. 2022). Moral dilemmas that investigate the permissibility of causing harm to prevent a greater harm also elicit different judgments from men and women: in a metaanalysis of 40 studies, men were more likely to find it permissible to cause harm to prevent a greater harm in this kind of moral dilemmas (Friesdorf et al. 2015). Hannikainen, Machery and Cushman (2018) have also shown that Millenials are more likely to find it permissible to cause harm to prevent a greater harm in the footbridge case than Gen Xers and Boomers, suggesting that the relevant moral norms might have culturally evolved.

Variation is not limited to sacrificial dilemmas (Stich and Machery in press). Cultural factors moderate the influence of valence on judgment about the intentionality of action that was discussed above (Robbins, Shepard and Rochat 2017): in two rural, traditional cultures (Samoa and Vanuatu) people were more likely to judge the good side effect than the bad side effect as intentional if the protagonist had a high status.

Another area of investigation focuses on the distinction between norms that are thought to be moral and norms that aren’t (see also Machery and Stich 2022 for the cross-cultural work on the moral/conventional distinction). Buchtel et al. (2015) have shown that the Mandarin translation of “immoral” applies to a surprisingly different set of behaviors than “immoral” in English: the former primarily applies to behaviors viewed as uncivilized, the latter often to harmful behavior (see also Dranseika, Berniūnas & Silius 2018). Berniūnas (2020) extends this research to the Mongolian translation of “moral.” Asking people to classify norms as moral and non-moral, Levine and colleagues (2021) have also shown that religious affiliation influences what counts as moral: religious Jews and non-believers have a very narrow moral domain, while Christians and Muslims tend to have a broad moral domain; surprisingly, Hindus fail to distinguish moral from non-moral norms (see also Dranseika, Berniūnas & Sousa 2016). This kind of findings has led Machery (2018) to propose that morality is a cultural invention that is not found in every culture (see also Stich 2018).

Judgments related to free will, control, blame, and punishment also vary across cultures (Hannikainen et al. 2019; for a different line of cross-cultural research on free will, see Sarkissian et al. 2010). In most cultures, people deny free will and control (and thus blame and punish less) when the agent’s action is described as antecedently caused; by contrast, they assign free will and control when the action originates stems from the agent’s own will even if she could not have done otherwise (a situation illustrated by Frankfurt cases). East Asians, however, differ in treating these two kinds of situations similarly: if the surrounding circumstances undercut the agent’s capacity to have done otherwise, they tend to deny her free will and control. East Asians’ greater attention to contextual factors when explaining behavior (Choi, Nisbett and Norenzayan 1999) might account for this finding (for related research, see Buchtel et al. 2018). Berniunas and colleagues (2021) have even argued that the concept of free will is a culture-specific concept, not found in most cultures.

3. Character, Wellbeing, Emotion, and Moral Standing

Until the 1950s, modern moral philosophy had largely focused on either consequentialism or deontology. The revitalization of virtue ethics led to a renewed interest in virtues and vices (e.g., honesty, generosity, fairness, dishonesty, stinginess, unfairness), in eudaimonia (often translated as ‘happiness’ or ‘flourishing’), and in the emotions. In recent decades, experimental work in psychology, sociology, and neuroscience has been brought to bear on the empirical grounding of philosophical views in these areas.

A virtue is a complex disposition comprising sub-dispositions to notice, construe, think, desire, and act in characteristic ways. To be generous, for instance, is (among other things) to be disposed to notice occasions for giving, to construe ambiguous social cues charitably, to desire to give people things they want, need, or would appreciate, to deliberate well about what they want, need, or would appreciate, and to act on the basis of such deliberation. Manifestations of such a disposition are observable and hence ripe for empirical investigation. Virtue ethicists of the last several decades have sometimes been optimistic about the distribution of virtue in the population. Alasdair MacIntyre claims, for example, that “without allusion to the place that justice and injustice, courage and cowardice play in human life very little will be genuinely explicable” (1984: 199). Julia Annas (2011: 8–10) claims that “by the time we reflect about virtues, we already have some.” Linda Zagzebski (2010) provides an “exemplarist” semantics for virtue terms that only gets off the ground if there are in fact many virtuous people.

Starting with Owen Flanagan’s Varieties of Moral Personality (1993), philosophers began to worry that empirical results from social psychology were inconsistent with the structure of human agency presupposed by virtue theory. In this framework, people are conceived as having more or less fixed traits of character that systematically order their perception, cognition, emotion, reasoning, decision-making, and behavior. For example, a generous person is inclined to notice and seek out opportunities to give supererogatorily to others. The generous person is also inclined to think about what would (and wouldn’t) be appreciated by potential recipients, to feel the urge to give and the glow of satisfaction after giving, to deliberate effectively about when, where, and how to give to whom, to come to firm decisions based on such deliberation, and to follow through on those decisions once they’ve been made. Other traits are meant to fit the same pattern, structuring perception, cognition, motivation, and action of their bearers. Famous results in social psychology, such as Darley and Batson’s (1973) Good Samaritan experiment, seem to tell against this view of human moral conduct. When someone helps another in need, they may do so simply because they are not in a rush, rather than because they are expressing a fixed trait like generosity or compassion.

In the virtue-theoretic framework, people are not necessarily assumed to already be virtuous. However, they are assumed to be at least potentially responsive to the considerations that a virtuous person would ordinarily notice and take into account. Flanagan (1993), followed by Doris (1998, 2002, in press), Harman (1999, 2000), and Alfano (2013), made trouble for this framework by pointing to social psychological evidence suggesting that much of people’s thinking, feeling, and acting is instead predicted by (and hence responsive to) situational factors that don’t seem to count as reasons at all—not even bad reasons or temptations to vice. Early discussions of these situational factors emphasized influences such as ambient sensibilia (sounds, smells, light levels, etc.), seemingly trivial and normatively irrelevant inducers of positive and negative moods, order of presentation of stimuli, and a variety of framing and priming effects, many of which are reviewed in Alfano (2013: 40–50). [ 7 ] It’s worth emphasizing the depth of the problem these studies appeared to pose. It’s not that they suggest that most people aren’t virtuous (although they do suggest that as well). It’s that they suggest that they undermine the entire framework in which people are conceived as cognitively sensitive and motivationally responsive to reasons. Someone whose failure to act virtuously because they gave in to temptation can be understood in the virtue-theoretic framework. Someone whose failure to act virtuously because they’d just been subliminally primed with physical coldness, which in turn is metaphorically associated with social coldness, finds no place in the virtue-theoretic framework. These sorts of effects push us to revamp our whole notion of agency and personhood (Doris 2015).

Some of the most surprising findings touted by critics of virtue ethics (e.g., social priming) now appear to be unreplicable (for discussion, see Alfano 2018), but this outcome does not provide much solace to virtue theorists. Early estimates suggested that individual difference variables typically explain less than 10% of the variance in people’s behavior (Mischel 1968)—though, as Funder and Ozer (1983) pointed out, situational factors may explain less than 16%. [ 8 ] More recent aggregated evidence indicates that situational factors explain approximately twice as much of the variance in human behavior as the five main trait factors (Rauthmann et al. 2014). Convergent evidence from both lexicographical and survey studies indicates that there are at least five dimensions of situations that reliably predict thought, feeling, and behavior: (1) negative valence, (2) adversity, (3) duty, (4) complexity, and (5) positive valence (Rauthmann and Sherman 2018).

According to Doris (2002, in press), the best explanation of this lack of cross-situational consistency is that the great majority of people have local rather than global, traits: they are not honest, courageous, or greedy, but they may be honest-while-in-a-good-mood, courageous-while-sailing-in-rough-weather-with-friends, and greedy-unless-watched-by-fellow-parishioners. In contrast, Christian Miller (2013, 2014) thinks the evidence is best explained by a theory of mixed global traits, such as the disposition to (among other things) help because it improves one’s mood. Such traits are global, in the sense that they explain and predict behavior across situations (someone with such a disposition will, other things being equal, typically help so long as it will maintain her mood), but normatively mixed, in the sense that they are neither virtues nor vices. Mark Alfano (2013) goes in a third direction, arguing that virtue and vice attributions tend to function as self-fulfilling prophecies. People tend to act in accordance with the traits that are attributed to them, whether the traits are minor virtues such as tidiness (Miller, Brickman, & Bolen 1975) and ecology-mindedness (Cornelissen et al. 2006, 2007), major virtues such as charity (Jensen & Moore 1977), cooperativeness (Grusec et al. 1978), and generosity (Grusec & Redler 1980), or vices such as cutthroat competitiveness (Grusec et al. 1978). On Alfano’s view, when people act in accordance with a virtue, they often do so not because they possess the trait in question, but because they think they do or because they know that other people think they do. He calls such simulations of moral character factitious virtues , and even suggests that the notion of a virtue should be revised to include reflexive and social expectations. [ 9 ]

It might seem that the criticisms that motivate these novel approaches to virtue miss their mark. After all, virtue ethicists needn’t (and often don’t) commit themselves to the claim that almost everyone is virtuous. Instead, many argue that virtue is the normative goal of moral development, and that people mostly fail in various ways to reach that goal. The argument from the fact that most people’s dispositions are not virtues to a rejection of orthodox virtue ethics, then, might be thought a non sequitur , at least for such views. But empirically-minded critics of virtue ethics do not stop there. They all have positive views about what sorts of dispositions people have instead of virtues. These dispositions are alleged to be so structurally dissimilar from virtues (as traditionally understood) that it may be psychologically unrealistic to treat (traditional) virtue as a regulative ideal. What matters, then, is the width of the gap between the descriptive and the normative, between the (structure of the) dispositions most people have and the (structure of the) dispositions that count as virtues.

Three leading defenses against this criticism have been offered. Some virtue ethicists (Kupperman 2009) have conceded that virtue is extremely rare, but argued that it may still be a useful regulative ideal. Others (Hurka 2006; Merritt 2000) have attempted to weaken the concept of virtue in such a way as to enable more people, or at least more behaviors, to count as virtuous. Still others (Kamtekar 2004; Russell 2009; Snow 2010; Sreenivasan 2002) have challenged the situationist evidence or its interpretation. While it remains unclear whether these defenses succeed, grappling with the situationist challenge has led both defenders and challengers of virtue ethics to develop more nuanced and empirically informed views. [ 10 ]

Philosophers have always been interested in what makes a human life go well, but recent decades have seen a dramatic increase in both psychological and philosophical research into happiness, well-being, and what makes for a good life. It is important to distinguish here between ‘good life’ in the sense of a life that goes well for the one who lives it, and a morally good life, since philosophers have long debated whether a morally bad person could enjoy a good life. The empirical study of wellbeing focuses primarily on lives that are good in the former sense: good for the person whose life it is. Second, we need to distinguish between a hedonically good life and an overall good life. A life that is hedonically good is one that the subject experiences as pleasant; an overall good life might not contain much pleasure but might be good for other reasons, such as what it accomplishes. We might decide, after investigation, that an overall good life must be a hedonically good life, but the two concepts are distinct.

With these distinctions in mind, we can see the relevance of experimental evidence to investigations in this area. First and perhaps most obviously, experiments can investigate our intuitions about what constitutes a good life, thereby giving us insight into the ordinary concepts of happiness, well-being, and flourishing. To this end, Phillips, Nyholm, and Liao (2014) investigated intuitions about the relationship between morality and happiness. Their results suggest that the ordinary conception of happiness involves both descriptive and normative components: specifically, we judge that people are happy if they are experiencing positive feelings that they ought to experience. So, to use their examples, a Nazi doctor who gets positive feelings from conducting his experiments is not happy. By contrast, a nurse who gets positive feelings from helping sick children is happy, though a nurse who is made miserable by the same actions is not happy.

Another set of experimental findings bearing on this question involves Nozick’s (1974: 44–45) experience machine thought experiment. In response to the hedonist’s claim that pleasure is the only intrinsic good, Nozick asks us to consider the following:

Suppose there was an experience machine that would give you any experience you desired. Super-duper neuropsychologists could stimulate your brain so that you would think and feel you were writing a great novel, or making a friend, or reading an interesting book. All the time you would be floating in a tank, with electrodes attached to your brain. Should you plug into this machine for life, preprogramming your life experiences? […] Of course, while in the tank you won’t know that you’re there; you’ll think that it’s all actually happening […] Would you plug in?

Nozick argues that our response to the experience machine reveals that well-being is not purely subjective: “We learn that something matters to us in addition to experience by imagining an experience machine and then realizing that we would not use it.” De Brigard (2010) reports finding that subjects’ intuitions about the experience were different if they were told they were already in such a machine, in which case they would not choose to unplug; he explains this in terms of the status quo bias. Weijers (2014) goes further, asking subjects about Nozick’s original scenario while also asking them to justify their response; he found that many of the justifications implied a kind of imaginative resistance to the scenario or cited irrelevant factors. He also found that respondents were more likely to say that a ‘plugged in life’ would be better when they were choosing for someone else, rather than for themselves. Löhr (2019) shows that a third of philosophers would stay in the machine and recommend it to others. Hindriks and Douven (2018) further show that people are more likely to agree to choose pleasurable, but illusory experiences in scenarios that are more realistic than the experience machine.

A second type of study involves investigating the causes and correlates of happiness, well-being, and life-satisfaction. These experiments look at the conditions under which people report positive affect or life-satisfaction, as well as the conditions under which they judge that their lives are going well. This is distinct from the first type of research, since the fact that someone reports an experience as being pleasurable does not necessarily tell us whether they would judge that experience to be pleasurable for someone else; there may be asymmetries in first- and third-person evaluations. Furthermore, this type of research can tell us how various candidates contribute to well-being from a first-person perspective, but that doesn’t settle the question of the concept of a good life. I might judge that my life is going well, yet fail to notice that I am doing so because I am in a very good mood, and that in fact I am not accomplishing any of my goals; if confronted with another person in a similar situation, I might not make the same judgment. Which of these judgments best represents our concept of well-being is a tricky question, and a normative one since experimental evidence alone may not settle it. As it turns out, experiments have uncovered a number of factors that influence our own reports and assessments of pleasure and well-being. We will discuss two areas of research in particular: reports of pleasures and pains, and judgments of life satisfaction.

First, in the realm of hedonic evaluation, there are marked divergences between the aggregate sums of in-the-moment pleasures and pains and ex post memories of pleasures and pains. For example, the remembered level of pain of a colonoscopy is well-predicted by the average of the worst momentary level of pain and the final level of pain; furthermore, the duration of the procedure has no measurable effect on ex post pain ratings (Redelmeier & Kahneman 1996). What this means is that people’s after-the-fact summaries of their hedonic experiences are not simple integrals with respect to time of momentary hedonic tone. If the colonoscopy were functionally completed after minute 5, but arbitrarily prolonged for another 5 minutes so that the final level of pain was less at the end of minute 10 than at the end of minute 5, the patient would retrospectively evaluate the experience as less painful. This complicates accounts of well-being in terms of pleasure (for example, Bentham’s 1789/1961 hedonism) insofar as it raises the question whether the pleasure being measured is pleasure as experienced in the moment, or retrospectively: if, in the very act of aggregating pleasure, we change the way we evaluate it, this is a complication for hedonism and for some versions of utilitarianism. Since well-being is supposed to be a normative notion capable of guiding both individual actions and social policy, findings like these also call into question what, exactly, we ought to be seeking to maximize: pleasurable moments, or the overall retrospective evaluation of pleasure.

Such findings have led some philosophers to seek out alternatives to hedonism in hopes of establishing a more empirically stable underpinning for well-being: in particular, the idea that well-being consists in life satisfaction. The most prominent psychologist in this field is Ed Diener [ 11 ] whose Satisfaction with Life Scale asks participants to agree or disagree with statements such as, “I am satisfied with my life” and “If I could live my life over, I would change almost nothing.” These questions seem to get at more stable and significant features of life than hedonic assessments in terms of pleasure and pain, and one might expect the responses to be more consistent and robust. However, two problems arise. The first is that participants’ responses to life satisfaction questionnaires may not be accurate reports of standing attitudes. Fox and Kahneman (1992), for instance, showed that, especially in personal domains people seem to value (friends and love life), what predicts participants’ responses is not recent intrapersonal factors but social comparison. Someone who has just lost a friend but still thinks of herself as having more friends than her peers will tend to report higher life satisfaction than someone who has just gained a friend but who still thinks of himself as having fewer friends than his peers.

Life satisfaction surveys were also believed to be subject to order effects. If a participant is asked a global life satisfaction question and then asked about his romantic life, the correlation between these questions tends to be near zero, but if the participant is asked the dating question first, the correlation tends to be high and positive (Strack, Martin & Schwarz 1988). Relatedly, weather and life-satisfaction were correlated when subjects were asked about weather first, but not when the weather question followed the life-satisfaction query (Schwarz & Clore 1983). Recent work has however cast doubts on this kind of results: Schimmack and Oishi (2005) did not replicate Strack et al.’s (1988) findings and Lucas and Lawless (2013) found no evidence for an effect of weather on life-satisfaction judgments (but see Connolly 2013). [ 12 ] Recent surveys suggest that the instability of life satisfaction surveys, which some philosophers have been taken for granted, has been exaggerated (Lucas 2018).

Schwarz’s findings and similar ones have led some philosophers (e.g., Haybron 2008) to argue that life-satisfaction judgments are too arbitrary to ever satisfy the requirements of a theory of well-being. In response, Tiberius and Plakias (2011) argue for an idealized life-satisfaction theory they call value-based life satisfaction , suggesting that by asking subjects to consider their life-satisfaction while attending to the domains they most value much of the instability plaguing the studies described above is removed, a claim they support with research showing that judgments made after priming subjects to think about their values demonstrate higher levels of retest stability (Schimmack & Oishi 2005).

As much of the previous discussion reveals, the relationship between emotion and moral judgment is one of the central concerns of both traditional and experimental moral philosophy. Our discussion of this topic will focus on two types of research: the role of emotion in moral reasoning generally, and the role of a specific emotion—disgust—in moral judgments.

One debate concerns whether hot, emotion-driven reasoning is necessarily better or worse than reasoning based only on cooler, more reflective thinking—a distinction sometimes referred to using Kahneman’s terminology of system 1/system 2 thinking. The terminology is not perfect, though, because Kahneman’s terms map onto a quick, automatic, unconscious system of judgments (system 1) and a slow, effortful, deliberative decision-making process (system 2), and as we saw above, this is not a distinction between emotion and reason, since rule-based judgments can be automatic and unconscious while emotional judgments might be effortful and conscious. The debate between Mikhail and Haidt is a debate over the extent to which emotions rather than rules explain our moral judgments; Singer and Greene’s arguments against deontology rest on the claim that emotion-backed judgments are less justified than their utilitarian counterparts.

One reason for thinking that moral judgments essentially involve some emotional component is that they tend to motivate us. Internalism is the view that there is a necessary connection between moral judgment and motivation. This contrasts with externalism , which doesn’t deny that moral judgments are usually motivating, but does deny that they are necessarily so, as the link between judgment and motivation is only contingent. Since emotions are intrinsically motivational, showing that moral judgments consist, even in part, of emotions would vindicate internalism. One route to this conclusion has involved surveying people’s intuitions about moral judgment. Nichols (2002: 289) asked subjects whether an agent who “had no emotional reaction to hurting other people” but claims to know that hurting others is wrong really understands that hurting others is wrong. He found that most subjects did attribute knowledge in such cases, suggesting that the ordinary concept of moral judgment is externalist, a claim that is further supported by Strandberg and Björklund (2013). An additional source of evidence comes from psychopaths and patients with traumatic brain injuries, both of whom show evidence of impaired moral functioning—though how one regards this evidence depends on which perspective one begins with: while externalists (Nichols 2002; Roskies 2003) claim that the existence of psychopaths provides a counterexample to the claim that moral judgment is motivating (since psychopaths lack empathy and an aversion to harming others), internalists (Smith 1994; Maibom 2005; Kennett & Fine 2008) argue that psychopaths don’t actually make full-fledged moral judgments. Psychologist Robert Hare (1993: 129) quotes a researcher as saying that, they “know the words but not the music.” Psychopaths also display other cognitive and affective deficiencies, as evidenced by their poor decision-making skills in other areas. This may mean that they should not be taken as evidence against internalism.

A reason for thinking that moral judgments ought not involve emotion is that emotions sometimes seem to lead to judgments that are distorted or off-track, or that seem otherwise unjustified. One emotion in particular is often mentioned in this context: disgust. This emotion, which seems to be unique to human animals and emerges relatively late in development (from the ages of about 5–8), involves a characteristic gaping facial expression, a tendency to withdraw from the object of disgust, a slight reduction in body temperature and heart rate, and a sense of nausea and the need to cleanse oneself. In addition, the disgusted subject is typically motivated to avoid and even expunge the offending object, experiences it as contaminating and repugnant, becomes more attuned to other disgusting objects in the immediate environment, and is inclined to treat anything that the object comes in contact with (whether physically or symbolically) as also disgusting. This last characteristic is often referred to as ‘contamination potency’ and it is one of the features that makes disgust so potent and, according to its critics, so problematic. The disgust reaction can be difficult to repress, is easily recognized, and empathically induces disgust in those who do recognize it. [ 13 ] There are certain objects that almost all normal adults are disgusted by (feces, decaying corpses, rotting food, spiders, maggots, gross physical deformities). But there is also considerable intercultural and interpersonal variation beyond these core objects of disgust, where the emotion extends into food choices, sexual behaviors, out-group members, and violations of social norms. Many studies have claimed to show that disgust is implicated in harsher moral judgments (Schnall, Haidt, & Clore 2008), citing experiments in which subjects filling out questionnaires in smelly or dirty rooms evaluated moral transgressions more harshly. Many of these studies have however failed to replicate, raising doubts about the influence of incidental disgust on moral judgment (e.g., Johnson, Cheung & Donnellan’s (2014) failed replication of Schnall et al. (2008); Ghelfi et al. 2020).

Others have gone further and argued that disgust might itself cause or comprise a part of moral judgment (Haidt 2001; Wheatley & Haidt 2005). If this is true, critics argue, we ought to be wary of those judgments, because disgust has a checkered past in multiple senses. First, it’s historically (and currently) associated with racism, sexism, homophobia and xenophobia; the language of disgust is often used in campaigns of discrimination and even genocide. Secondly, disgust’s evolutionary history gives us reason to doubt it. Kelly (2011) argues that the universal bodily manifestations of disgust evolved to help humans avoid ingesting toxins and other harmful substances, while the more cognitive or symbolic sense of offensiveness and contamination associated with disgust evolved to help humans avoid diseases and parasites. This system is later recruited for an entirely distinct purpose: to help mark the boundaries between in-group and out-group, and thus to motivate cooperation with in-group members, punishment of in-group defectors, and exclusion of out-group members.

If Kelly’s account of disgust is on the right track, it seems to have a number of important moral upshots. One consequence, he argues, is “disgust skepticism” (139), according to which the combination of disgust’s hair trigger and its ballistic trajectory mean that it is especially prone to incorrigible false positives that involve unwarranted feelings of contamination and even dehumanization. Hence, “the fact that something is disgusting is not even remotely a reliable indicator of moral foul play” but is instead “irrelevant to moral justification” (148).

It is important to note that the skeptical considerations Kelly raises are specific to disgust and its particular evolutionary history, so they aren’t intended to undermine the role of all emotions in moral judgment. Still, if Kelly is correct, and if disgust is implicated in lots of moral judgments, we may have a reason to be skeptical of many of our judgments. Plakias (2011, 2017) argues against the first half of this antecedent, claiming that Kelly and other ‘disgust skeptics’ are wrong to claim that the purposes of moral and physical disgust are totally distinct; she suggests that disgust is sometimes a fitting response to moral violations that protects against social contagion. May (2014) argues against the second half, claiming that disgust’s role in moral judgment has been significantly overblown; at most, we have evidence that disgust can, in certain cases, slightly amplify moral judgments that are already in place. Recent empirical work indicates that incidental disgust has little effect on the harshness of moral judgments, though dispositional disgust-sensitivity does (Landy & Goodwin 2015; Landy & Piazza 2019).

A creature has moral standing if its interests are morally relevant to the agents whose actions impact it. Stones don’t have moral standing, people do. Moral philosophers disagree about the grounds of moral standing, i.e., that in virtue of which a creature has moral standing. Some argue that the capacity to feel gives a creature moral standing (e.g., Bentham 1781/2011), others favor autonomy (e.g., Kant 2001). What about lay people (for review, see Goodwin 2015)? According to Gray, Gray, and Wegner (2007), lay people side with Bentham: Whether a creature can suffer determines whether it has morally relevant interests (see also Robbins & Jack 2006 and Knobe & Prinz 2008).

However, the influence of another historical tradition, which like Kant highlights the connection between rationality and autonomy and moral standing, suggests that the capacity to feel might not be the whole story. Sytsma and Machery (2012) provided evidence for the two-source hypothesis: both rationality and the capacity to feel underwrite the ascription of moral standing by lay people. Others have since identified further factors that influence the ascription of moral standing (e.g., Piazza, Landy & Goodwin 2014), and they have examined how information about the grounds of moral standing can be used by people in a self-serving manner (Piazza & Loughnan 2016). Recent work connects moral standing ascription to, on the one hand, vegetarianism and the treatment of animals (e.g., Piazza & Loughnan 2016) and, on the other, the psychological processes underlying dehumanization (Machery 2021).

4. Metaethics and Experimental Moral Philosophy

Metaethics steps back from moral theorizing to ask about the nature and function of morality. While first-order ethics seeks to explain what we should do, metaethics seeks to explain the status of those theories themselves: what are their metaphysical commitments, and what evidence do we have for or against them? Which epistemology best characterizes our moral practices? What is the correct semantics for moral language? These questions might not seem obviously empirical, but insofar as it attempts to give an account of moral semantics, epistemology, and ontology, metaethics aims, in part, to capture or explain what we do when we engage in moral talk, judgment, and evaluation. To the extent that metaethics sees itself as characterizing our ordinary practice of morality, it is therefore answerable to empirical data about that practice. To the extent that a theory claims that we are mistaken or in widespread error about the meaning of moral language, or that we lack justification for our core moral beliefs, this is taken to be a strike against that theory. For example, relativism is often criticized on the grounds that it requires us to give up the (putatively) widespread belief that moral claims concern objective matters of fact and are true or false independently of our beliefs or attitudes. We have already seen several ways that experimental data bears on theories about moral reasons (the debate between internalists and externalists) and the epistemology of moral judgment (the debate over the role of intuitions). In this section we will examine experimental contributions to the debate over moral realism, arguments about moral disagreement, and moral language.

Much contemporary metaethics relies on assumptions about the nature of ordinary moral thought, discourse, and practice; metaethicists tend to see their project as essentially conservative. For example, Michael Smith writes that the first step in metaethical theorizing is to “identify features that are manifest in ordinary moral practice” and the second step is to “make sense of a practice having these features.” (1994) This assumption has had a major impact on the debate between realists and anti-realists, with realists claiming to best capture the nature of ordinary moral discourse: “We begin as (tacit) cognitivists and realists about ethics,” says Brink (1989), and then “we are led to some form of antirealism (if we are) only because we come to regard the moral realist’s commitments as untenable… Moral realism should be our metaethical starting point, and we should give it up only if it does involve unacceptable metaphysical and epistemological commitments.”

But experimental work has cast doubt on this claim, beginning with Darley and Goodwin (2008), and continued by James Beebe (2014) and others (Wright et al. 2013; Campbell & Kumar 2012; Goodwin & Darley 2010; Sarkissian et al. 2011; but see Sousa et al. 2021; for review, see Pölzler & Wright 2019). Goodwin and Darley asked subjects to rate their agreement with statements drawn from the moral, ethical, and aesthetic domain, and asked subjects whether they agreed with the statement (for example, “before the 3rd month of pregnancy, abortion for any reason (of the mother’s) is morally permissible,”), whether they thought it represented a fact or an opinion or attitude , and whether, if someone were to disagree with them about the statement, at least one of the disputants would have to be mistaken. (We will say more about the authors’ use of disagreement as a proxy for realism in the following section.) In general, subjects rated moral statements as less factual than obviously factual statements (e.g. “the earth is at the center of the universe,”) but more factual than statements about matters of taste or etiquette. What is striking about these findings is not just that people are not straightforwardly realist, but that they seem to treat moral questions variably (Wright, Grandjean & McWhite 2013): some are treated as matters of fact, others as matters of opinion. This pattern has been replicated in several studies, and persists even when subjects are allowed to determine for themselves which issues to assign to the moral domain, suggesting that subjects do not think moral claims are uniformly objective

A question that remains is how to explain this variation: are people being inconsistent? Are they tracking something besides the moral question—perhaps the degree of consensus that exists about a question? Further research may help shed some light on these issues, but even if the questions are answered in the affirmative, the realist’s claim to capture folk morality is called into question, since these experiments suggest that folk intuitions are either not uniformly realist, or they are confused (and hence poorly suited for a role in metaethical theorizing). Another response to these findings is that they reveal a kind of folk metaethical pluralism. For example, Michael Gill (2008, 2009) and Walter Sinnott-Armstrong (2009) have suggested a noncognitivist treatment of some areas of morality and cognitivism about others. This response is under-motivated by empirical data, however, since such data shows at most that our judgments about the extent to which moral claims describe mind-independent facts is variable, and not that their semantics itself varies. Nor does such data settle the question whether our moral judgments are beliefs or another conative state: while experimental data can reveal a role for emotion in moral judgment, as discussed above, it does not show that in such cases belief is absent. We will discuss limitations on experimental moral philosophy in more detail in Section 5 below. For now, it seems that data about folk realism are best viewed as undermining one of the most commonly-cited sources of evidence for moral realism, namely, that it captures our ordinary moral discourse and practice better than its competitors. A further question, open to exploration, is whether an anti-realist view might do better at capturing and explaining our folk intuitions than realist competitors.

As we saw at the beginning of this entry, some of the earliest thinking in empirically-informed moral philosophy concerns moral disagreement. Brandt and Ladd conducted in-depth investigations into the moral codes of other groups, and some contemporary moral philosophers have argued for continuing attention to the empirical details of moral disagreement. This is partly due to the influence of Mackie’s (1977: 36–37) formulation of what he dubbed ‘the argument from relativity’ in terms of an inference to the best explanation: the best explanation of the nature and persistence of moral diversity, Mackie argues, is that our moral judgments represent “ways of life,” rather than “perceptions, most of them seriously inadequate and badly distorted, of objective moral values.” Realists have tended to respond to the argument by pointing to other possible explanations of disagreement that are consistent with objectivity, such as mistakes about the non-moral facts, irrationality, and failures of impartiality and imagination (e.g., Brink 1984; Sturgeon 1988; Smith 1994; Shafer-Landau 2003; for an overview and analysis of realist responses, see Loeb 1998).

Here it is useful to recall Brandt’s admonition that “bare information about intercultural differences” will not suffice to settle the debate. Because the argument from disagreement turns, in part, on both the existence of moral disagreement and the best explanation for it, evaluating the prospects for the argument requires attention to the empirical details of actual moral disagreements, rather than conjecture about the outcomes of possible moral disagreements. For example, Doris and Plakias (2008) discuss several instances of cross-cultural moral disagreement, and assess the prospects for applying what they call ‘defusing explanations’ to these cases. A defusing explanation is one that accounts for the disagreement in terms of a non-moral difference or an epistemic shortcoming on the part of one or more disputant, thereby showing that it is not, in fact, a moral disagreement. Their argument and the experiments they cite are discussed in detail in the entry on empirical moral psychology, so we will not discuss them in detail here; for now, we will note that such explanations are difficult to assess via survey methods alone. This is why it is especially helpful to look to the anthropological record, as Oliver Curry et al. (2019) do in a recent publication. Curry hypothesizes that morality comprises stable, cooperative solutions to recurrent problems that can be modeled as non-zero-sum games. There are a variety of such recurrent problems, and game theory has established a suite of analytical tools for diagnosing and solving them. Curry and his colleagues show that such solutions are always seen as either morally good or morally neutral in societies at various stages of development, from small-band hunter gatherers to industrialized democracies. This research suggests that philosophers may have greatly exaggerated the extent of moral disagreement that actually exists.

One reason disagreement is a useful measure of objectivity is that the impossibility of faultless disagreement is taken to be characteristic of questions concerning objective matters of fact. That is, while we might concede the possibility of faultless disagreements about matters concerning the deliciousness of foods or the merits of a sports team, when we disagree over moral issues, we think that there is a correct answer and that therefore at least one disputant is getting things wrong (for a discussion of the analogy between food and morality, see Loeb 2003). To the extent that people judge a disagreement to be faultless, we might think that they are evincing a kind of anti-realism about the issue under dispute. This is yet another way disagreement can bear on the realism/antirealism debate. Can experimental evidence involving disagreement tell us anything about the semantics of moral language?

One reason to think it can is that the very idea of faultless disagreement strikes some as incoherent. In cases where one individual thinks (or says) that pistachio ice cream is delicious and another thinks (or says) that it is disgusting, we understand the two parties as expressing their own personal preference. To explain the apparent faultlessness of the dispute, we reinterpret their thoughts or utterances as expressing something like, “pistachio ice cream is delicious [disgusting] to me .” Because the two parties do not genuinely contradict one another, we need not say that one of them is mistaken. Faultlessness is therefore supposed to be a point in favor of the moral anti-realist, since it seems to imply that there is no single content about which the parties disagree (and about which one might be mistaken).

By contrast, realists claim that their view is better able to capture our intuition that there is a genuine disagreement at stake when one person says that stealing is wrong and another says that stealing is not wrong. In these cases, realists argue, we have the intuition that there really is a conflict, and only a theory on which moral language involves attributing properties to acts and things, rather than reporting or expressing speakers’ attitudes, can capture this intuition.

We have already seen some data bearing on this issue in our discussion of folk realism above. The claim here is not about realism per se, but about whether experimental evidence can give us insight into the semantics of moral language, since our intuitions about whether there is genuine faultlessness can tell us about whether there is a single shared content between two utterances—a single proposition that one party asserts and another denies—or whether the two parties’ utterances contain implicit relativizations. This has, at least, been the assumption guiding much of the debate over disagreement and its implication for moral semantics. In recent work, however, John Khoo and Joshua Knobe (2018) have cast doubt on this assumption; their experiments indicate that subjects do not see disagreement as requiring exclusionary content—a single proposition that one party accepts and the other rejects. Intuitions about disagreement may thus not be as straightforwardly tied to moral semantics as philosophers have thought: judgments that two individuals genuinely disagree about some claim do not necessarily imply a single shared content between the two speakers. This work is still in early stages, but it reveals the complications involved in reading semantics off disagreement.

A further challenge for attempts to experimentally investigate moral semantics is the debate within antirealism between cognitivism and noncognitivism. According to the cognitivist, ordinary moral sentences are best understood as factual assertions, expressing propositions that attribute moral properties (such as rightness or goodness) to things (such as actions or characters). Noncognitivists (including their contemporary representatives, the expressivists) hold that moral language has a fundamentally different function, to express attitudes or to issue commands, for example. While this debate seems ripe for experimental investigation, the noncognitivist typically acknowledges that their view is a reforming one. Furthermore, the semantics of our terms may be opaque to ordinary users, to the extent that we cannot read off semantics from intuitions but must investigate them indirectly. Lastly, the cognitivist and noncognitivist can agree on a number of empirical features of moral judgment and discourse; the challenge for experimentalists is to find predictions that confirm one view while disconfirming the other. This is a relatively new area of investigation and, while not without challenges, ripe for exploration.

5. Criticisms of Experimental Moral Philosophy

Experimental moral philosophy far outstrips what we have been able to cover here, and many issues and areas of productive research have barely been touched upon. For example, experimental evidence is relevant to moral questions in bioethics, such as euthanasia, abortion, genetic screening, and placebogenic interventions. Likewise, experiments in behavioral economics and cognitive psychology are being employed in asking moral questions about public policy (Bicchieri & Chavez 2010; Bicchieri & Xiao 2009). We neglect these issues only because of lack of space. In the few words remaining, we explore some potential criticisms of experimental philosophy.

As a young field, experimental philosophy suffers from various problems with experimental design and interpretation. These are not insurmountable problems (Machery & Doris 2017), and they are problems faced by related fields, such as social psychology, cognitive psychology, and behavioral economics.

One issue that has recently come to the fore is the problem of replication (Romero 2019). [ 14 ] Statistical analysis is not deductive inference, and the mere fact that statistical analysis yields a positive result does not guarantee that anything has been discovered. Typically, an experimental result is only treated as “real” if its p -value is at most .05, but such a value just indicates, roughly, the probability that the observation in question or a more extreme observation would have been made if the null hypothesis were true. It is not the probability that the null hypothesis is false given the observation. [ 15 ] So, even when statistical analysis indicates that the null hypothesis is to be rejected, that indication can be erroneous, and the null hypothesis might still be quite plausible.

We should also expect other failures of replication because of a bias built into the system of funding experimentation and publishing results. Since experimentalists are reluctant to report (and even discouraged by journal editors and referees from reporting) null results (i.e., results where the p -value is more than .05), for every published result there may be any number of unpublished non-results (Rosenthal 1979).

Another worry is that simultaneously testing many intuition-probes can lead unwary experimenters on fishing expeditions. Suppose an experimental philosopher conducts an experiment with two conditions: in the experimental condition, participants are primed with deterministic ideas, while in the control condition they are not primed one way or another. She asks participants twenty different questions about their moral intuitions, for instance, whether there is free will, whether malefactors deserve to be punished, whether virtue deserves to be rewarded, and so on. She then makes pairwise comparisons of their responses to each of the questions in an attempt to figure out whether deterministic priming induces changes in moral intuitions. She thus makes twenty independent comparisons, each at the industry-standard 5% level. Suppose now for the sake of argument that there is no effect—that all null hypotheses are true. In that case, the probability that at least one of these tests will result in a Type I error (rejecting the null hypothesis even though it is true) is 64%. More generally, when an experimenter performs n independent comparisons at the 5% level, the probability of at least one Type I error is \(1-.95^n\). This problem can be addressed by various procedures, most notably the Tukey method and the Bonferroni method. [ 16 ]

Multiple testing without correction is a form of p-hacking (Simmons, Nelson & Simohnson 2011). “P-hacking” refers to a family of practices that increase the probability of obtaining a significant result by capitalizing on chance, such as dropping outliers, testing statistical models with and without covariates, and uncorrected multiple testing. While p-hacking might be surprisingly frequent in psychology (John, Loewenstein & Prelec 2012), it appears rare in experimental philosophy (Stuart, Colaço & Machery 2018).

The best way to tell whether such a result carries any evidential value is for the experiment to be replicated—preferably by another research group. If a result cannot be robustly replicated, it is probably a mirage. Such mirages have turned up to a disturbing extent recently, as Daniel Kahneman has famously pointed out (Yong 2012; see also Wagenmakers et al. 2012). Kahneman proposed a “daisy chain” of replication, where no result in psychology would be published until it had been successfully replicated by another prominent lab. This proposal has not yet been (and may never be) instituted, but it has raised the problem of replication to salience, and a related project has taken off. The reproducibility project in psychology aims to establish the extent to which prominent, published results can be replicated. [ 17 ] Experimental philosophers have followed suit with their own replication project (see the Other Internet Resources). This work has recently yielded encouraging fruit: a large collaborative replication effort suggests that approximately 7 out of 10 experimental philosophy results can be reproduced, whereas similar efforts show that less than half of the results in biomedicine, economics, and psychology are replicable (Cova et al. 2021, Other Internet Resources). On the other hand, as discussed throughout this entry, many influential experimental studies in moral psychology have failed to replicate.

One might object that the real problem with experimental moral philosophy is not with science, but with its relevance (or more precisely, its irrelevance) to moral philosophy. The objection is that moral philosophy is concerned not with how we are and what we do, but with how we ought to be and what we ought to do. As such, it is a normative enterprise, and is unaffected by empirical results. Science is hard, but so is morality; if we fail to understand and live up to the demands of the latter, that doesn’t show a problem with our moral theory but with our moral natures.

Experimental philosophers can agree with this objection, up to a point. No one is suggesting that we read morality directly off survey results. But, to return to the point with which we began, while morality is normative, it is also essentially practical. Moral theory is a theory about what we ought to do: a theory about how creatures like us ought to conduct ourselves and interact with one another. A morality completely divorced from our natures, that demanded acts impossible from us, would surely be unacceptable. This is not just a point about experimental philosophy; utilitarianism is sometimes critiqued as making unrealistic demands of impartiality. Alongside the famous proscription against deriving an ought from an is , we also find the dictum that ought implies can . The exact extent to which morality can be demanding without being unrealistic is itself a philosophical question, and so experimental moral philosophy works in conjunction with philosophical analysis; it does not aim to eliminate it. Exactly how the two relate to each other, and how empirical evidence will bear on and influence debates in moral theory in the future, is a contested issue, but surely traditional moral theory and experimental moral philosophy have much to learn from one another (Doris, Machery & Stich 2017).

We need to proceed cautiously here. No one doubts that what we ought to do depends on how things are non-morally. For example, the moral claim that a given man deserves to be punished presupposes the non-moral fact that he committed the crime. It should come as no surprise, then, that experimental evidence might be relevant in this way to morality. Whether experimental evidence is relevant to discovering the fundamental moral principles—those meant to be put into action one way or another depending on how the world is non-morally—is still subject to debate.

Another version of this argument says that fundamental moral philosophical principles are, if true at all, necessarily true, and that empirical research can establish at best only contingent truths. [ 18 ] But if fundamental moral theories are necessary, then they are necessary for creatures like us . And one thing that empirical investigation can do is to help establish what sorts of creatures we are. Imagination needs material to work with. When one sits in one’s armchair, imagining a hypothetical scenario, one makes a whole host of assumptions about what people are like, how psychological processes work, and so on. These assumptions can be empirically well or poorly informed. It’s hard to see why anyone could doubt that being well informed is to be preferred. Likewise it’s hard to see how anyone could doubt the relevance of experimental evidence to better grounding our empirical assumptions, in this case our assumptions relevant to moral philosophy. Exactly how experimental—or more broadly, empirical—evidence is relevant, and how relevant it is, are at present hotly contested matters.

• Abelson, R., 1997. “On the surprising longevity of flogged horses: Why there is a case for the significance test”, Psychological Science , 8(1): 12–15.
• Adams, F., & Steadman, A., 2004. “Intentional action in ordinary language: Core concept or pragmatic understanding?” Analysis , 64: 173–181.
• Adams, F., & Steadman, A., 2007. “Folk concepts, surveys, and intentional action”, in C. Lumer (ed.), Intentionality, deliberation, and autonomy: The action-theoretic basis of practical philosophy , Aldershot: Ashgate, 17–33.
• Ahlenius, H., & Tännsjö, T., 2012. “Chinese and Westerners respond differently to the trolley dilemmas”, Journal of Cognition and Culture , 12: 195–201.
• Alfano, M., 2013. Character as Moral Fiction , Cambridge: Cambridge University Press.
• –––, 2016. Moral Psychology: An Introduction , London: Polity.
• –––, 2018. “A plague on both your houses: virtue theory after situationism and repligate”, Teoria , 38: 115–122.
• Alfano, M., Beebe, J., & Robinson, B., 2012. “The centrality of belief and reflection in Knobe-effect cases”, The Monist , 95(2): 264–289.
• Alicke, M., 2008. “Blaming badly”, Journal of Cognition and Culture , 8: 179–186.
• Annas, J., 2011. Intelligent Virtue , Oxford: Oxford University Press.
• Apsler, R., 1975. “Effects of embarrassment on behavior toward others”, Journal of Personality and Social Psychology , 32: 145–153.
• Austin, P., Mamdani, M., Juurlink, D., Hux, J., 2006. “Testing multiple statistical hypotheses resulted in spurious associations: A study of astrological signs and health”, Journal of Clinical Epidemiology , 59(9): 964–969.
• Ayer, A.J., 1936. Language Truth, and Logic , London: Gollancz.
• Bago, B., et al., 2022. “Situational factors shape moral judgements in the trolley dilemma in Eastern, Southern and Western countries in a culturally diverse sample”, Nature Human Behaviour , 1–16.
• Banerjee, K., Huebner, B., & Hauser, M., 2010. “Intuitive moral judgments are robust across demographic variation in gender, education, politics, and religion: A large-scale web-based study”, Journal of Cognition and Culture , 10(1/2): 253–281.
• Baron, R., 1997. “The sweet smell of … helping: Effects of pleasant ambient fragrance on prosocial behavior in shopping malls”, Personality and Social Psychology Bulletin , 23: 498–503.
• Baron, R., & Kenny, D., 1986. “The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations”, Journal of Personality and Social Psychology , 51: 1173–82.
• Baron, R.A., & Thomley, J., 1994. “A whiff of reality: Positive affect as a potential mediator of the effects of pleasant fragrances on task performance and helping”, Environment and Behavior , 26: 766–784.
• Beebe, J.R., 2013. “A Knobe effect for belief ascriptions”, Review of Philosophy and Psychology , 4(2): 235–258.
• –––, 2014. “How different kinds of disagreement impact folk metaethical judgments”, in J.C. Wright & H. Sarkissian (2014), Advances in Experimental Moral Psychology: Affect, Character, and Commitment , 167–187 (London: Continuum).
• Beebe, J.R., & Buckwalter, W., 2010. “The epistemic side-effect effect”, Mind & Language , 25: 474–498.
• Beebe, J.R., & Jensen, M., 2012. “Surprising connections between knowledge and action: The robustness of the epistemic side-effect effect”, Philosophical Psychology , 25(5): 689–715.
• Berker, S., (2009). “The normative insignificance of neuroscience”, Philosophy & Public Affairs , 37: 293–329.
• Bentham, J., 1789 [1961]. An Introduction to the Principles of Morals and Legislation , Garden City: Doubleday. Originally published in 1789.
• Berniūnas, R., 2020. “Mongolian yos surtakhuun and WEIRD ”morality“”, Journal of Cultural Cognitive Science , 4: 59–71.
• Berniūnas, R., Beinorius, A., Dranseika, V., Silius, V., & Rimkevičius, P., 2021. “The weirdness of belief in free will”, Consciousness and Cognition , 87: 103054.
• Berniūnas, R., Dranseika, V., & Sousa, P., 2016. “Are there different moral domains? Evidence from Mongolia”, Asian Journal of Social Psychology , 19: 275–282.
• Bicchieri, C. and Chavez, A., 2010. “Behaving as expected: Public information and fairness norms”, Journal of Behavioral Decision Making , 23(2): 161–178.
• Bicchieri, C. and Xiao, E., 2009. “Do the right thing, but only if others do so”, Journal of Behavioral Decision Making , 22: 191–209.
• Blake, P., McAuliffe, K., and Warneken, F., 2014. “The developmental origins of fairness: The knowledge-behavior gap”, Trends in Cognitive Sciences , 18(11): 559–561.
• Bloom, P., 2013. Just Babies: The Origins of Good and Evil , New York: Crown.
• Bonnefon, J.-F., Sharriff, A., and Rahwan, I., 2016. “The social dilemma of autonomous vehicles”, Science , 352(6293): 1573–1576.
• Brandt, R., 1954. Hopi Ethics: A Theoretical Analysis , Chicago: University of Chicago Press.
• –––, 1998. A Theory of the Right and the Good , Prometheus Books.
• Brink, D., 1984. “Moral realism and the sceptical arguments from disagreement and queerness”, Australasian Journal of Philosophy , 62(2): 111–125.
• Buchtel, E. E., Guan, Y., Peng, Q., Su, Y., Sang, B., Chen, S. X., & Bond, M. H., 2015. “Immorality east and west: Are immoral behaviors especially harmful, or especially uncivilized?”, Personality and Social Psychology Bulletin , 41: 1382–1394.
• Buchtel, E. E., et al., 2018. “A sense of obligation: Cultural differences in the experience of obligation”, Personality and Social Psychology Bulletin , 44: 1545–1566.
• Buckwalter, W. & Stich, S., 2014. “Gender and philosophical intuition”, in Knobe & Nichols (eds.), Experimental Philosophy (Volume 2), Oxford: Oxford University Press.
• Campbell, R. & Kumar, V., 2012. “Moral reasoning on the ground”, Ethics , 122(2): 273–312.
• Cappelen, H., 2012. Philosophy Without Intuitions , Oxford: Oxford University Press.
• Case, T., Repacholi, B., & Stevenson, R., 2006. “My baby doesn’t smell as bad as yours: The plasticity of disgust”, Evolution and Human Behavior , 27(5): 357–365.
• Choi, I., Nisbett, R. E., & Norenzayan, A., 1999. “Causal attribution across cultures: Variation and universality”, Psychological Bulletin , 125: 47–63.
• Chomsky, N., 1965. Aspects of the Theory of Syntax , Cambridge, MA: MIT Press.
• Cohen, J., 1994. “The Earth is round \((p \lt .05)\)”, American Psychologist , 49(12): 997–1003.
• Cornelissen, G., Dewitte, S., Warlop, L., Liegeois, A., Yzerbyt, V., Corneille, O., 2006. “Free bumper stickers for a better future: The long term effect of the labeling technique”, Advances in Consumer Research , 33: 284–285.
• Cova, F., et al., 2021. “Estimating the reproducibility of experimental philosophy”, Review of Philosophy and Psychology , 12: 9–44.
• Curry, O., Mullins, D., and Whitehouse, H., 2019. “Is it good to cooperate? Testing the theory of morality-as-cooperation in 60 societies”, Current Anthropology , 60: 47–69.
• Cushman, F. & Greene, J., 2012. “Finding faults: How moral dilemmas illuminate cognitive structure”, Social Neuroscience , 7(3): 269–279.
• Cushman, F. & Young, L., 2009. “The psychology of dilemmas and the philosophy of morality”, Ethical Theory and Moral Practice , 12(1): 9–24.
• –––, 2011. “Patterns of judgment derive from nonmoral psychological representations”, Cognitive Science , 35(6): 1052–1075.
• Darley, J. and Batson, C. D., 1973. “From Jerusalem to Jericho: A study of situational and dispositional variables in helping behavior”, Journal of Personality and Social Psychology , 27: 100–108.
• De Brigard, F., 2010. “If you like it, does it matter if it’s real?” Philosophical Psychology , 23(1): 43–57
• Deutsch, M., 2016. “Arguments, intuitions, and philosophical cases: A note on a metaphilosophical dialectic”, Philosophical Forum , 47(3–4): 297–307.
• Diener, E., Scollon, C., & Lucas, R., 2003. “The evolving concept of subjective wellbeing: The multifaceted nature of happiness”, Advances in Cell Aging and Gerontology , 15: 187–219.
• Diener, E., Emmons, R., Larsen, R., & Griffin, S., 2010. “The satisfaction with life scale”, Journal of Personality Assessment , 49(1): 71–5.
• Doris, J., 1998. “Persons, situations, and virtue ethics”, Noûs , 32(4): 504–540.
• –––, 2002. Lack of Character: Personality and Moral Behavior , Cambridge: Cambridge University Press.
• –––, in press. Character Trouble: Undisciplined Essays on Moral Agency and Personality , Oxford: Oxford University Press.
• Doris, J. & Plakias, A., 2008a. “How to argue about disagreement: Evaluative diversity and moral realism”, in Sinnott-Armstrong (2008b), 303–332.
• –––, 2008b. “How to Find a Disagreement: Philosophical Diversity and Moral Realism”, in Sinnott-Armstrong (2008b), 345–54.
• –––, 2015. Talking to Our Selves: Reflection, Ignorance, and Agency . Oxford: Oxford University Press.
• Doris, J., Stich, S. P., Philipps, & Walmsley, L. 2020. “Moral Psychology: Empirical Approaches”, The Stanford Encyclopedia of Philosophy (Spring 2020 Edition), Edward N. Zalta (ed.), URL = < https://plato.stanford.edu/archives/win2012/entries/moral-psych-emp/ >.
• Doris, J. M., Machery, E., & Stich, S. P., 2017. “Can psychologists tell us anything about morality?”, The Philosophers’ Magazine , 77: 24–29.
• Dranseika, V., Berniūnas, R., & Silius, V., 2018. “Immorality and bu daode, unculturedness and bu wenming”, Journal of Cultural Cognitive Science , 2: 71–84.
• Dwyer, S., 1999. “Moral competence”, in K. Murasugi & R. Stainton (eds.), Philosophy and Linguistics , Boulder, CO: Westview Press, 169–190.
• –––, 2009. “Moral dumbfounding and the linguistic analogy: Implications for the study of moral judgment”, Mind and Language , 24: 274–96.
• Everett, D., 2005. “Cultural constraints on grammar and cognition in Pirahã: Another look at the design features of human language”, Current anthropology , 46: 621–646.
• Flanagan, O., 1983. Varieties of Moral Personality: Ethics and Psychological Realism , Cambridge: Harvard University Press.
• Foot, P., 1978. Virtues and Vices and Other Essays in Moral Philosophy , Berkeley, CA: University of California Press; Oxford: Blackwell.
• Fox, C. & Kahneman, D., 1992. “Correlations, causes and heuristics in surveys of life satisfaction”, Social Indicators Research , 27: 221–234.
• Friesdorf, R., Conway, P., & Gawronski, B., 2015. “Gender differences in responses to moral dilemmas: a process dissociation analysis”, Personality and Social Psychology Bulletin , 41: 696–713.
• Funder, D. & Ozer, D., 1983. “Behavior as a function of the situation”, Journal of Personality and Social Psychology , 44: 107–112.
• Gill, M., 2008. “Metaethical Variability, Incoherence, and Error”, in Sinnott-Armstrong (2008b), 387–402.
• –––, 2009. “Indeterminacy and variability in meta-ethics”, Philosophical Studies , 145(2): 215–234.
• Gold, N., Colman, A. M., & Pulford, B. D., 2014. “Cultural differences in responses to real-life and hypothetical trolley problems”, Judgment and Decision making , 9: 65–76.
• Goodwin, G. P., 2015. E“xperimental approaches to moral standing”, Philosophy Compass , 10: 914–926.
• Goodwin, G. P. and Darley, M., 2008. “The psychology of metaethics: Exploring objectivism”, Cognition , 106(3): 1339–1366.
• Goodwin, G. P. & Darley, J., 2010. “The perceived objectivity of ethical beliefs: Psychological findings and implications for public policy”, Review of Philosophy and Psychology , 1: 161–188.
• Graham, J., Meindl, P., Beall, E., Johnson, K. M., & Zhang, L., 2016. “Cultural differences in moral judgment and behavior, across and within societies”, Current Opinion in Psychology , 8: 125–130.
• Gray, H., Gray, K., & Wegner, D., 2007. “Dimensions of mind perception”, Science , 619: 315.
• Greene, J., 2008. “The secret joke of Kant’s soul”, in Sinnott-Armstrong (2008c), 35–80.
• –––, 2012. “Reflection and reasoning in moral judgment”, Cognitive Science , 36(1): 163–177.
• –––, 2014. “Beyond point-and-shoot morality: Why cognitive (neuro) science matters for ethics”, Ethics , 124: 695–726.
• Greene, J., Morelli, S., Lowenberg, K., Nystrom, L., & Cohen, J., 2008. “Cognitive load selectively interferes with utilitarian moral judgment”, Cognition , 107(3): 1144–1154.
• Greene, J., Nystrom, L., Engell, A., Darley, J., & Cohen, J., 2004. “The neural bases of cognitive conflict and control in moral judgment”, Neuron , 44: 389–400.
• Greene, J., Sommerveille, R., Nystrom, L., Darley, J., & Cohen, J., 2001. “An fMRI investigation of emotional engagement in moral judgment”, Science , 293: 2105–8.
• Grusec, J. & Redler, E., 1980. “Attribution, reinforcement, and altruism: A developmental analysis”, Developmental Psychology , 16(5): 525–534.
• Grusec, J., Kuczynski, L., Rushton, J., & Simutis, Z., 1978. “Modeling, direct instruction, and attributions: Effects on altruism”, Developmental Psychology , 14: 51–57.
• Ghelfi, E., et al., 2020. “Reexamining the effect of gustatory disgust on moral judgment: A multilab direct replication of Eskine, Kacinik, and Prinz (2011)”, Advances in Methods and Practices in Psychological Science , 3: 3–23.
• Haidt, J., 2001. “The emotional dog and its rational tail: A social intuitionist approach to moral judgment”, Psychological Review , 108(4): 814–834.
• –––, 2012. The Righteous Mind: Why Good People are Divided by Politics and Religion , New York: Pantheon.
• Haidt, J. & Björklund, F., 2008. “Social intuitionists answer six questions about moral psychology”, in Sinnott-Armstrong (2008b), 181–218.
• Hallen, B., 1986. Knowledge, Belief, and Witchcraft: Analytic Experiments in African Philosophy , Oxford: Oxford University Press.
• –––, 2000. The Good, the Bad, and the Beautiful: Discourse about Values in Yoruba Culture , Bloomington: Indiana University Press.
• Hare, R., 1993. Without Conscience: The Disturbing World of the Psychopaths Among Us , New York: Guilford Press.
• Hannikainen, I. R., Machery, E., & Cushman, F. A., 2018. “Is utilitarian sacrifice becoming more morally permissible?”, Cognition , 170: 95–101.
• Hannikainen, I. R., et al., 2019. “For whom does determinism undermine moral responsibility? Surveying the conditions for free will across cultures”, Frontiers in Psychology , 2428.
• Harman, G., 1999. “Moral philosophy meets social psychology: Virtue ethics and the fundamental attribution error. ” Proceedings of the Aristotelian Society (New Series), 119: 316–331.
• –––, 2000a. “The nonexistence of character traits”, Proceedings of the Aristotelian Society , 100: 223–226.
• –––, 2000b. Explaining Value and Other Essays in Moral Philosophy , New York: Oxford University Press.
• –––, 2003. No character or personality. Business Ethics Quarterly , 13(1): 87–94.
• –––, 2008. “Using a linguistic analogy to study morality”, in W. Sinnott-Armstrong (2008a), 345–352.
• Hauser, M., 2006. Moral Minds: How Nature Designed a Universal Sense of Right and Wrong , New York: Ecco Press/Harper Collins.
• Hauser, M., Chomsky, N., and Fitch, W., 2002. “The faculty of language: What is it, who has it, and how does it evolve”, Science , 298: 1569–1579.
• Hauser, M., Young, L., & Cushman, F., 2008. “Reviving Rawls’s linguistic analogy: Operative principles and the causal structure of moral actions”, in W. Sinnott-Armstrong (2008b), 107–144.
• Hauser, M., Cushman, F., Young, L., Kang-Xing Jin, R., & Mikhail, J., 2007. “A dissociation between moral judgments and justifications”, Mind & language , 22: 1–21.
• Haybron, D., 2008. The Pursuit of Unhappiness , Oxford: Oxford University Press.
• Heathwood, C., 2005. “The problem of defective desires”, Australasian Journal of Philosophy , 83(4): 487–504.
• Hindriks, F., & Douven, I., 2018. “Nozick’s experience machine: An empirical study”, Philosophical Psychology , 31: 278–298.
• Hurka, T., 2006. “Virtuous act, virtuous dispositions”, Analysis , 66(289): 69–76.
• Inbar, Y., Pizarro, Knobe, J. & Bloom, P., 2009. “Disgust sensitivity predicts intuitive disapproval of gays”, Emotion , 9(3): 435–443.
• Isen, A. & Levin, P., 1972. “The effect of feeling good on helping: Cookies and kindness”, Journal of Personality and Social Psychology , 21: 384–388.
• Jackson, F., 1998. From Metaphysics to Ethics , Oxford: Oxford University Press.
• Jensen, A. & Moore, S., 1977. “The effect of attribute statements on cooperativeness and competitiveness in school-age boys”, Child Development , 48: 305–307.
• John, L. K., Loewenstein, G., & Prelec, D., 2012. “Measuring the prevalence of questionable research practices with incentives for truth telling”, Psychological science , 23: 524–532.
• Johnson, D. J., Cheung, F., & Donnellan, M. B., 2014. “Does cleanliness influence moral judgments?”, Social Psychology , 45: 209–215.
• Kahane, G., Everett, J. A., Earp, B. D., Farias, M., & Savulescu, J., 2015. “‘Utilitarian’judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good”, Cognition , 134: 193–209.
• Kahneman, D., Diener, E., & Schwartz, N. (eds), (2003). Wellbeing: The Foundations of Hedonic Psychology , New York: Russell Sage.
• Kahneman, D., 2011. Thinking, Fast and Slow , New York: Farrar, Straus, & Giroux.
• Kamtekar, R., 2004. “Situationism and virtue ethics on the content of our character”, Ethics , 114(3): 458–491.
• Kant, I., 2001. Lectures on Ethics , ed. J. B. Schneewind. Cambridge: Cambridge University Press.
• Kelly, D., 2011. Yuck! The Nature and Moral Significance of Disgust , Cambridge: MIT Press.
• Kennett, J., 2006. “Do psychopaths really threaten moral rationalism?” Philosophical Explorations , 9(1): 69–82.
• Khoo, J. and Knobe, J., 2018. “Moral disagreement and moral semantics,” Noûs , 52(1): 109–143.
• Kline, R. B., 2005. Principles and Practice of Structural Equation Modeling , New York: Guilford Press.
• Kluckhohn, C., 1959. Mirror for Man , New York: McGraw Hill.
• Kneer, M., & Machery, E., 2019. “No luck for moral luck”, Cognition , 182: 331–348.
• Knobe, J., 2003. “Intentional action and side effects in ordinary language”, Analysis , 63(3): 190–194.
• –––, 2004a. “Folk psychology and folk morality: Response to critics”, Journal of Theoretical and Philosophical Psychology , 24: 270–279.
• –––, 2004b. “Intention, intentional action and moral considerations”, Analysis , 2: 181–187.
• –––, 2006. “The concept of intentional action: A case study in the uses of folk psychology”, Philosophical Studies , 130(2): 203–231.
• –––, 2007. “Reason explanation in folk psychology”, Midwest Studies in Philosophy , 31: 90–107.
• –––, 2009. “Cause and norm”, Journal of Philosophy , 106(11): 587–612.
• –––, 2010. “Person as scientist, person as morality”, Behavioral and Brain Sciences , 33: 315–329.
• –––, 2011. “Is morality relative? Depends on your personality”, The Philosopher’s Magazine , 52: 66–71.
• Knobe, J., & Mendlow, G., 2004. “The good, the bad and the blameworthy: Understanding the role of evaluative reasoning in folk psychology”, Journal of Theoretical and Philosophical Psychology , 24: 252–258.
• Knobe, J., & Prinz, J., 2008. “Intuitions about Consciousness: Experimental Studies”, Phenomenology and Cognitive Sciences , 7: 67–85.
• Kohlberg, L., 1984. The Psychology of Moral Development: The Nature and Validity of Moral Stages , San Francisco: Harper and Row.
• Kupperman, J., 2009. Virtue in virtue ethics. Journal of Ethics , 13(2–3): 243–255.
• Ladd, J., 1957. The Structure of a Moral Code: A Philosophical Analysis of Ethical Discourse Applied to the Ethics of the Navaho Indians , Cambridge, MA: Harvard University Press.
• Landy, J. F. and Goodwin, G., 2015. “Does incidental disgust amplify moral judgment? A meta-analytic review of experimental evidence”, Perspectives on Psychological Science , 10(4): 518–536.
• Landy, J. F. and Piazza, J., 2019. “Reevaluating moral disgust: sensitivity to many affective states predicts extremity in many evaluative judgments”, Social Psychological and Personality Science , 10: 211–219.
• Lam, B., 2010. “Are Cantonese speakers really descriptivists? Revisiting cross-cultural semantics”, Cognition , 115: 320–332.
• Lanteri, A., Chelini, C., & Rizzello, S., 2008. “An experimental investigation of emotions and reasoning in the trolley problem”, Journal of Business Ethics , 83: 789–804.
• Latané, B., & Darley, J., 1968. “Group inhibition of bystander intervention in emergencies”, Journal of Personality and Social Psychology , 10: 215–221.
• –––, 1970. The Unresponsive Bystander: Why Doesn’t He Help? New York: Appleton-Century-Crofts.
• Latané, B., & Nida, S., 1981. “Ten years of research on group size and helping”, Psychological Bulletin , 89: 308–324.
• Latané, B., & Rodin, J., 1969. “A lady in distress: inhibiting effects of friends and strangers on bystander intervention”, Journal of Experimental Psychology , 5: 189–202.
• Levine, S., Rottman, J., Davis, T., O’Neill, E., Stich, S., & Machery, E., 2021. “Religious affiliation and conceptions of the moral domain”, Social Cognition , 39: 139–165.
• Liao, S. M., Wiegmann, A., Alexander, J., & Vong, G., 2012. “Putting the trolley in order: Experimental philosophy and the loop case”, Philosophical Psychology , 25: 661–671.
• Lindauer, M., & Southwood, N., 2021. “How to cancel the Knobe effect: the role of sufficiently strong moral censure”, American Philosophical Quarterly , 58: 181–186.
• Likert, R., 1932. “A technique for the measurement of attitudes”, Archives of Psychology , 140: 1–55.
• Loeb, D., 1998. “Moral realism and the argument from disagreement”, Philosophical Studies , 90(3): 281–303.
• –––, 2003. “Gastronomic value realism: A cautionary tale”, Journal of Theoretical and Philosophical Psychology , 21(1): 30–49.
• Lombrozo, T., 2009. “The role of moral commitments in moral judgment”, Cognitive Science , 33: 273–286.
• Löhr, G., 2019. “The experience machine and the expertise defense”, Philosophical Psychology , 32: 257–273.
• Lucas, R., 2007. “Adaptation and the set-point model of subjective wellbeing: Does happiness change after major life events?” Current Directions in Psychological Science , 16(2): 75–79.
• –––, 2018. “Reevaluating the strengths and weaknesses of self-report measures of subjective”, in E. Diener, S. Oishi, & L. Tay (eds.), Handbook of Well-Being . Salt Lake City: DEF Publishers.
• Lucas, R., Clark, C., Georgellis, Y., & Diener, E., 2003. “Reexamining adaptation and the set point model of happiness: Reactions to changes in marital status”, Journal of Personality and Social Psychology , 84(3): 527–539.
• Luetge, C., Rusch, H., and Uhl, M. (eds.), 2014. Experimental Ethics: Towards an Empirical Moral Philosophy , London: Palgrave.
• Machery, E., 2008. “The folk concept of intentional action: Philosophical and experimental issues”, Mind & Language , 2: 165–189.
• –––, 2017. Philosophy Within Its Proper Bounds . Oxford: Oxford University Press.
• –––, 2018. “A historical invention”, in K. Gray & J. Graham (eds.), Atlas of Moral Psychology . Guilford Publications, 259–265.
• –––, 2021. “Dehumanization and the loss of moral standing”, in M. Kronfeldner (ed.), The Routledge Handbook of Dehumanization . New York: Routledge, 145–158.
• Machery, E., & Doris, J. M., 2017. “An open letter to our students: Doing interdisciplinary moral psychology”, in B. G. Voyer and T. Tarantola (eds.), Moral Psychology . Springer, Cham, 119–143.
• Machery, E., & Stich, S. P., 2022. “The moral/conventional distinction”, Stanford Encyclopedia of Philosophy ( Summer 2022 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/sum2022/entries/moral-conventional/>.
• Machery, E., Mallon, R., Nichols, S., & Stich, S., 2004. “Semantics, cross-cultural style”, Cognition , 92(3): B1–B12.
• MacIntyre, A., 1998. A Short History of Ethics: A History of Moral Philosophy from the Homeric Age to the Twentieth Century , South Bend, IN: University of Notre Dame Press
• –––, 1984. After Virtue: A Study in Moral Theory , South Bend, IN: University of Notre Dame Press.
• Mackie, J. L., 1977. Ethics: Inventing Right and Wrong , New York: Penguin.
• Maibom, H. L., 2005. “Moral unreason: The case of psychopathy.” Mind and Language , 20(2): 237–57.
• Matthews, K. E., & Cannon, L. K., 1975. “Environmental noise level as a determinant of helping behavior”, Journal of Personality and Social Psychology , 32: 571–577.
• May, J., 2014. “Does disgust influence moral judgment?” Australasian Journal of Philosophy , 92(1): 125–141.
• McDonald, K., Graves, R., Yin, S., Weese, T., & Sinnott-Armstrong, W. 2021. “Valence framing effects on moral judgments: A meta-analysis”, Cognition , 212: 104703.
• McGilvray, J., 2005. The Cambridge Companion to Chomsky. Cambridge: Cambridge University Press.
• McGuire, J., Langdon, R., Coltheart, M., & Mackenzie, C., 2009. “A reanalysis of the personal/impersonal distinction in moral psychology research”, Journal of Experimental Social Psychology , 45: 577–580.
• Merritt, M., 2000. “Virtue ethics and situationist personality psychology”, Ethical Theory and Moral Practice , 3(4): 365–383.
• Mikhail, J., 2005. “Chomsky and moral philosophy”, in J. McGilvray (2005), 235–53.
• –––, 2007. “Universal moral grammar: Theory, evidence, and the future”, Trends in Cognitive Sciences , 11: 143–152.
• –––, 2008. “The poverty of the moral stimulus”, in W. Sinnott-Armstrong (2008a), 353–360.
• –––, 2009. “Moral grammar and intuitive jurisprudence: A formal model of unconscious moral and legal language”, in B. H. Ross, D. M., Bartels, C. W., Bauman, L. J. Skitka, and D. L. Medin (eds.), Psychology of Learning and Motivation (Volume 50: Moral Judgment and Decision Making). New York: Academic Press.
• –––, 2011. Elements of Moral Cognition: Rawls’s Linguistic Analogy and the Cognitive Science of Moral and Legal Judgment , Cambridge: Cambridge University Press.
• Miller, C., 2013. Moral Character: An Empirical Theory , Oxford: Oxford University Press.
• –––, 2014. Character and Moral Psychology , Oxford: Oxford University Press.
• Miller, R., Brickman, P., & Bolen, D., 1975. “Attribution versus persuasion as a means for modifying behavior”, Journal of Personality and Social Psychology , 31(3): 430–441.
• Mischel, W., 1968. Personality and Assessment , New York: Wiley.
• Moody-Adams, M. M., 1997. Fieldwork in Familiar Places:Morality, Culture, and Philosophy , Cambridge, MA: Harvard University Press.
• Moore, A. B., Lee, N. L., Clark, B. A., & Conway, A. R., 2011. “In defense of the personal/impersonal distinction in moral psychology research: Cross-cultural validation of the dual process model of moral judgment”, Judgment and Decision Making , 6: 186–195.
• Nadelhoffer, T., 2004. “On praise, side effects, and folk ascriptions of intentionality”, Journal of Theoretical and Philosophical Psychology , 24: 196–213.
• –––, 2006. “Bad acts, blameworthy agents, and intentional actions: Some problems for jury impartiality”, Philosophical Explorations , 9: 203–220.
• Naess, A., 1938. Truth as Conceived by Those Who are Not Professional Philosophers , Oslo: Jacob Dybwad.
• Navarrete, C. D., McDonald, M. M., Mott, M. L., & Asher, B., 2012. “Virtual morality: Emotion and action in a simulated three-dimensional ”trolley problem“”, Emotion , 12: 364–370.
• Nichols, S., 2002. “On the genealogy of norms: A case for the role of emotion in cultural evolution”, Philosophy of Science , 69: 234–255.
• –––, 2004. Sentimental Rules , Oxford: Oxford University Press.
• –––, 2021. Rational Rules: Towards a Theory of Moral Learning , Oxford: Oxford University Press.
• Nichols, S., Kumar, S., Lopez, T., Ayars, A., and Chan, H.-Y., 2016. “Rational learners and moral rules”, Mind and Language , 31(5): 530–554.
• Ngo, L., Kelley, M. Coutlee, C., McKell Carter, R., Sinnott-Armstrong, W., & Huettel, S.A., 2015, “Two distinct neural mechanisms for ascribing and denying intentionality”, Nature Scientific Reports , 5: 17390.
• Nozick, R., 1974. Anarchy, State, and Utopia , Basic Books.
• Nussbaum, M., 2001. The Fragility of Goodness: Luck and Ethics in Greek Tragedy and Philosophy , Cambridge: Cambridge University Press.
• Pereboom, D., 2001. Living Without Free Will , New York: Cambridge University Press.
• Pettit, D. & Knobe, J., 2009. “The pervasive impact of moral judgment”, Mind and Language , 24(5): 586–604.
• Phelan, M., & Sarkissian, H., 2009. “Is the ‘trade-off hypothesis’ worth trading for?” Mind and Language , 24: 164–180.
• Phillips, J., Misenheimer, L., & Knobe, J., 2011. “The ordinary concept of happiness (and others like it)”, Emotion Review , 71: 929–937.
• Phillips, J., Nyholm, S., & Liao, S., 2014. “The good in happiness”, Oxford Studies in Experimental Philosophy (Volume 1), Oxford: Oxford University Press, 253–293.
• Piaget, J., 1965. The Moral Judgment of the Child , New York: Free Press.
• Piazza, J., & Loughnan, S., 2016. “When meat gets personal, animals’ minds matter less: Motivated use of intelligence information in judgments of moral standing”, Social Psychological and Personality Science , 7: 867–874.
• Piazza, J., Landy, J. F., & Goodwin, G. P., 2014. “Cruel nature: Harmfulness as an important, overlooked dimension in judgments of moral standing”, Cognition , 131: 108–124.
• Plakias, A., 2017. “The response model of moral disgust”, Synthese , first online 3 June 2017. doi:10.1007/s11229-017-1455-3
• –––, 2013. “The good and the gross”, Ethical Theory and Moral Practice , 16(2): 261–78.
• Pölzler, T., & Wright, J. C., 2019. “Empirical research on folk moral objectivism”, Philosophy compass , 14: e12589.
• Prinz, J., 2007. The Emotional Construction of Morals , Oxford, Oxford University Press.
• –––, 2008. “Resisting the linguistic analogy: A commentary on Hauser, Young, and Cushman”, in W. Sinnott-Armstrong (2008b), 157–170.
• Railton, P., 2014. “The affective dog and its rational tale: Intuition and attunement”, Ethics , 124(4): 813–859.
• Rauthmann, J. and Sherman, R., 2018. “The description of situations: Towards replicable domains of psychological situation characteristics”, Journal of Personality and Social Psychology , 114(3): 482–488.
• Rawls, J., 1971. A Theory of Justice , Cambridge, MA: Harvard University Press.
• Redelmeier, D. & Kahneman, D., 1996. “Patients’ memories of painful medical treatments: Real-time and retrospective evaluations of two minimally invasive procedures”, Pain , 1: 3–8.
• Regan, J., 1971. “Guilt, perceived injustice, and altruistic behavior”, Journal of Personality and Social Psychology , 18: 124–132.
• Rehren, P. & Sinnott- Armstrong, W., 2021. “Moral framing effects within subjects”, Philosophical Psychology , 34: 611–636.
• Robbins, P., & Jack, A., 2006. “The phenomenal stance”, Philosophical Studies , 127: 59–85.
• Robbins, E., Shepard, J., & Rochat, P., 2017. “Variations in judgments of intentional action and moral evaluation across eight cultures”, Cognition , 164: 22–30.
• Robinson, B., Stey, P., & Alfano, M., 2013. “Virtue and vice attributions in the business context: An experimental investigation”, Journal of Business Ethics , 113(4): 649–661.
• Roedder, E. & Harman, G., 2010. “Linguistics and moral theory”, in J. Doris (ed.), The Moral Psychology Handbook , 273–296. Oxford University Press.
• Romero, F., 2019. “Philosophy of science and the replicability crisis”, Philosophy Compass , 14: e12633.
• Rose, D., Livengood, J., Sytsma, J., Machery, E., 2012. “Deep trouble for the deep self”, Philosophical Psychology , 25: 629–646.
• Rosenthal, R., 1979. “The file drawer problem and tolerance for null results”, Psychological bulletin , 86: 638–641.
• Rönnow-Rasmussen, T., 2011. Personal Value , Oxford: Oxford University Press.
• Roskies, A., 2003. “Are ethical judgments intrinsically motivational? Lessons from ‘acquired sociopathy.’ ” Philosophical Psychology , 16(1): 51–66.
• Russell, D., 2009. Practical Intelligence and the Virtues , Oxford: Oxford University Press.
• Sarkissian, H., Park, J., Tien, D., Wright, J. C., & Knobe, J., 2011. “Folk moral relativism”, Mind and Language , 26(4): 482–505.
• Sarkissian, H., Chatterjee, A., De Brigard, F., Knobe, J., Nichols, S., & Sirker, S., 2010) “Is belief in free will a cultural universal?”, Mind & Language , 25: 346–358.
• Sayre-McCord, Geoffrey (ed.), 1988. Essays on Moral Realism , Ithaca: Cornell University Press.
• Sayre-McCord, Geoffrey,, 2008. “Moral Semantics and Empirical Inquiry”, in Sinnott-Armstrong (2008b), 403–412.
• Scaife, R. & Webber, J., 2013. “Intentional side-effects of action”, Journal of Moral Philosophy , 10: 179–203.
• Schimmack, U. & Oishi, S., 2005. “The influence of chronically and temporarily accessible information on life satisfaction judgments”, Journal of Personality and Social Psychology , 89(3): 395–406.
• Schnall, S., Haidt, J., and Clore, 2008. “Disgust as embodied moral judgment”, Personality and Social Psychology Bulletin , 34(8): 1096–1109.
• Schwartz, S. & Gottlieb, A., 1991. “Bystander anonymity and reactions to emergencies”, Journal of Personality and Social Psychology , 39: 418–430.
• Schwarz, N., and Clore, G., 1983. “Mood, Misattribution, and Judgments of Well-Being: Informative and Directive Functions of Affective States”, Journal of Personality and Social Psychology , 45(3): 513–523.
• Schwitzgebel, E., 2009. “Do ethicists steal more books?” Philosophical Psychology , 22(6): 711–725
• Schwitzgebel, E. & Cushman, F., 2012. “Expertise in moral reasoning? Order effects on moral judgment in professional philosophers and non-philosophers”, Mind and Language , 27(2): 135–153.
• –––, 2015. “Philosophers’ biased judgments persist despite training, expertise and reflection”, Cognition , 141: 127–137.
• Schwitzgebel, E. & Rust, J., 2010. “Do ethicists and political philosophers vote more often than other professors?” Review of Philosophy and Psychology , 1(2): 189–199.
• Schwitzgebel, E., Rust, J., Huang, L., Moore, A., & Coates, J., 2011. “Ethicists’ courtesy at philosophy conferences”, Philosophical Psychology , 25(3): 331–340.
• Shafer–Landau, R., 2003. Moral Realism: A Defence , Oxford: Oxford University Press.
• Simmons, J. P., Nelson, L. D., & Simonsohn, U., 2011. “False-positive psychology: Undisclosed flexibility in data collection and analysis allows presenting anything as significant”, Psychological science , 22: 1359–1366.
• Singer, P., 2005.“Ethics and Intuitions”, The Journal of Ethics , 9(3–4): 331–352.
• Singer, P. & de Lazari-Radak, K., forthcoming. From the Point of View of the Universe: Sidgwick and Contemporary Ethics , Oxford: Oxford University Press
• Sinnott-Armstrong, W., 2009. “Mixed-up meta-ethics”, Philosophical Issues , 19(1): 235–56
• ––– (ed.), 2008a. Moral Psychology: The Evolution of Morality: Adaptations and Innateness (Volume 1), Cambridge, MA: MIT Press.
• ––– (ed.), 2008b. Moral Psychology: The Cognitive Science of Morality: Intuition and Diversity (Volume 2), Cambridge, MA: MIT Press.
• ––– (ed.), 2008c. Moral Psychology: The Neuroscience of Morality: Emotion, Brain Disorders, and Development (Volume 3), Cambridge, MA: MIT Press.
• –––, 2008d. “Framing moral intuitions”, In Sinnott-Armstrong (2008b), 47–76.
• Sinnott-Armstrong, W., Mallon, R., McCoy, T., & Hull, J., 2008. “Intention, temporal order, and moral judgments”, Mind and Language , 23(1): 90–106.
• Smith, M., 1994. The Moral Problem , Oxford: Blackwell.
• Snow, N., 2010. Virtue as Social Intelligence: An Empirically Grounded Theory , New York: Routledge.
• Sorokowski, P., Marczak, M., Misiak, M., & Białek, M., 2020. “Trolley dilemma in Papua. Yali horticulturalists refuse to pull the lever”, Psychonomic Bulletin & Review , 27 : 398–403.
• Sousa, P., Allard, A., Piazza, J., and Goodwin, G. P., 2021. “Folk moral objectivism: The case of harmful actions”, Frontiers in Psychology , 2776.
• Sreenivasan, G., 2002. “Errors about errors: Virtue theory and trait attribution”, Mind , 111(441): 47–66.
• Sripada, C., 2005. “Punishment and the strategic structure of moral systems”, Biology and Philosophy , 20(4): 767–789.
• –––, 2010. “The deep self model and asymmetries in folk judgments about intentional action”, Philosophical Studies , 151(2): 159–176.
• –––, 2011. “What makes a manipulated agent unfree?” Philosophy and Phenomenological Research , 85(3): 563–593. doi:10.1111/j.1933-1592.2011.00527.x
• –––, 2012. “Mental state attributions and the side-effect effect”, Journal of Experimental Psychology , 48(1): 232–238.
• Sripada, C. & Konrath, S., 2011. “Telling more than we can know about intentional action”, Mind and Language , 26(3): 353–380.
• Stich, S. P., 2018. “The moral domain”, in K. Gray & J. Graham (eds.), Atlas of Moral Psychology . Guilford Publications, 547–555.
• Stich, S. P., & Machery, E., in press. “Demographic differences in philosophical intuition: A reply to Joshua Knobe”, Review of Philosophy and Psychology .
• Stich, S. P. & Weinberg, J., 2001. “Jackson’s empirical assumptions”, Philosophy and Phenomenological Research , 62(3): 637–643.
• Strack, F., Martin, L., & Schwartz, N., 1988. “Priming and communication: Social determinants of information use in judgments of life satisfaction”, European Journal of Social Psychology , 18: 429–442.
• Strandberg, C. & Björklund, F., 2013. “Is moral internalism supported by folk intuitions?” Philosophical Psychology , 26(3): 319–335.
• Strawson, P. F., 1962. “Freedom and resentment”, Proceedings of the British Academy , 48: 1–25.
• Strohminger, N., Caldwell, B., Cameron, D., Schaich Borg, J., and Sinnott-Armstrong, W., 2014. “Implicit morality: A methodological survey,” in C. Luetge, H. Rusch, and M. Uhl 2014: 133–156.
• Stuart, M. T., Colaço, D., & Machery, E., 2019. “P-curving x-phi: Does experimental philosophy have evidential value?”, Analysis , 79: 669–684.
• Sturgeon, N., 1988. “Moral Explanations,” in Sayre-McCord 1988: 229–255.
• Sytsma, J. & Livengood, J., 2011. “A new perspective concerning experiments on semantic intuitions”, Australasian Journal of Philosophy , 89(2): 315–332.
• Sytsma, J., & Machery, E., 2012. “The two sources of moral standing”, Review of Philosophy and Psychology , 3: 303–324.
• Thomson, J. J., 1971. “A defense of abortion”, Philosophy and Public Affairs , 1: 47–66.
• Tobia, K., Buckwalter, W., & Stich, S. P., 2013. “Moral intuitions: Are philosophers experts?”, Philosophical Psychology , 26: 629–638.
• Trivers, R. L., 1971. “The evolution of reciprocal altruism”, Quarterly Review of Biology , 46: 35–57.
• Wagenmakers, E.-J., Wetzels, R., Borsboom, D., van der Maas, H., & Kievit, R., 2012. “An agenda for purely confirmatory research”, Perspectives on Psychological Science , 7(6): 632–638.
• Weijers, D., 2014. “Nozick’s experience machine is dead, long live the experience machine!” Philosophical Psychology , 27(4): 513–535.
• Weinberg, J. M., Nichols, S., & Stich, S. P., 2001. “Normativity and epistemic intuitions”, Philosophical topics , 29: 429–460.
• Weyant, J., 1978. “Effects of mood states, costs, and benefits on helping”, Journal of Personality and Social Psychology , 36: 1169–1176.
• Wheatley, T. and Haidt, J., 2005. “Hypnotically induced disgust makes moral judgments more severe”, Psychological Science , 16(10): 780–784.
• Wiegman, I., 2017. “The evolution of retribution: Intuition undermined”, Pacific Philosophical Quarterly , 98(2): 490–510.
• Wiegmann, A., Horvath, J., & Meyer, K., 2020. “Intuitive expertise and irrelevant options”, In Lombrozo, Knobe, & Nichols (eds.), Oxford Studies in Experimental Philosophy , Volume 3. Oxford: Oxford University Press, 275–310.
• Wright, J. C., Grandjean, P., & McWhite, C., 2013. “The meta-ethical grounding of our moral beliefs: Evidence for meta-ethical pluralism”, Philosophical Psychology , 26(3): 336–361.
• Wright, J. C. & H Sarkissian (eds.), 2014. Advances in Experimental Moral Psychology: Affect, Character, and Commitment , London: Continuum.
• Yong, E., 2012. “Nobel laureate challenges psychologists to clean up their act: Social-priming research needs ‘daisy chain’ of replication”, Nature News , available online , doi:10.1038/nature.2012.11535
• Zagzebski, L., 2010. “Exemplarist virtue theory”, Metaphilosophy , 41(1): 41–57.
• Zhong, C.-B., Bohns, V., & Gino, F., 2010. “Good lamps are the best police: Darkness increases dishonesty and self-interested behavior”, Psychological Science , 21(3): 311–314.

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character, moral | character, moral: empirical approaches | cognitivism vs. non-cognitivism, moral | emotion | ethics: virtue | intuition | moral anti-realism | moral epistemology | morality: and evolutionary biology | moral psychology: empirical approaches | moral realism | moral relativism | well-being

Acknowledgments

The authors thank James Beebe, Gunnar Björnsson, Wesley Buckwalter, Roxanne DesForges, John Doris, Gilbert Harman, Dan Haybron, Chris Heathwood, Antti Kauppinen, Daniel Kelly, Joshua Knobe, Clayton Littlejohn, Josh May, John Mikhail, Sven Nyholm, Brian Robinson, Chandra Sripada, Carissa Veliz, several anonymous referees, and the editors of this encyclopedia for helpful comments and suggestions.

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• > The Enlightenment's Animals
• > Animal Experimentation and Ethics in the Early Modern Era

Book contents

• Frontmatter
• List of Illustrations
• Introduction
• Part I Animal Experimentation
• Part II From Philosophy to Historiography in the Enlightenment
• Part III Art and Economics
• Bibliography

1 - Animal Experimentation and Ethics in the Early Modern Era

Published online by Cambridge University Press:  21 November 2020

The use of animals in scientific experimentation, or, to use the modern term, vivisection, is far from a modern phenomenon. With the rise of modern empirical experimental methodology in the early modern era, it became increasingly common and by the seventeenth century was consistently practiced by anatomists with varying medical, anatomical, and zoological interests. Anita Guerrini's recent detailed history of animal experimentation in seventeenth-century France mirrors a scientific praxis common, to various degrees, in several European countries at the time. In what follows, however, the scientific aspects of animal experimentation will not interest us in themselves, and we will concentrate only on the ethical dilemmas which this posed for at least some early modern scientists. At a time when such experimentation was done without the use of effective anesthetics, the suffering caused to animals was considerable and, for those conducting the experiments, quite conspicuous. The fact that some of the scientists struggled with the moral complications this entailed offers a good vantage-point from which to begin discussing the consideration of animals in pre-Enlightenment Europe.

Animal experimentation, which had become relatively uncommon in the Middle Ages compared with the experiments conducted in antiquity, was conducted in the Renaissance on an increasingly wide scale. The Catholic Church treated the matter in a manner similar to stoic philosophy, supporting the claim that animals, due to their difference from human beings, were devoid of the right to protection from being experimented upon. One of the most prominent Renaissance scientists who performed vivisections in sixteenth-century Italy was Andreas Vesalius. He was one of the first early modern scientists who recognized the suffering that vivisection caused to animals, yet he accorded it no particular significance, writing that there was very little to learn from vivisection of the brain, since “whether we like it or not, but merely out of consideration for our native theologians, we must deprive brute creatures of reason and thought, although their structure is the same as that of man.” And he continued to note that had he not been at personal risk from religious authorities, he indeed would have performed such experiments on animal brains.

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• Animal Experimentation and Ethics in the Early Modern Era
• Nathaniel Wolloch
• Book: The Enlightenment's Animals
• Online publication: 21 November 2020
• Chapter DOI: https://doi.org/10.1017/9789048539321.003

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The Ethics of Animal Experimentation: A Critical Analysis and Constructive Christian Proposal

Assistant Professor of Theology

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The ethical treatment of animals is one of serious academic interest today. Specifically, both the practice of animal experimentation and ethical concerns about it have a long history, going virtually back to the ancient Greek period and continuing to the present day. With new breakthroughs in science and technology, it is likely that this practice will be with us for a long time to come. Thus, this book provides an interdisciplinary approach to the topic by utilizing the insights of cognitive ethology, philosophy, science, and Christian theology in order to present a benign approach to the ethical treatment of experimental animals. The reality and existence of animal minds, animal pain, and animal suffering provide the foundation for animal rights, and subsequently, for more positive treatment. Concrete suggestions are offered with regard to more humane animal legislation, improved animal husbandry conditions, as well as concrete guidelines that offset the burdens to animals against the benefits to humans. The ultimate result is a more humane practice in experimentation, modeled somewhat on the practice of pet keeping, in which experimental animals are viewed not only as having instrumental value but intrinsic value as well.

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• Published: 23 January 2020

Joining forces: the need to combine science and ethics to address problems of validity and translation in neuropsychiatry research using animal models

• Franck L. B. Meijboom   ORCID: orcid.org/0000-0002-0752-016X 1 , 2 ,
• Elzbieta Kostrzewa 1 &
• Cathalijn H. C. Leenaars 2 , 3 , 4  

Philosophy, Ethics, and Humanities in Medicine volume  15 , Article number:  1 ( 2020 ) Cite this article

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Current policies regulating the use of animals for scientific purposes are based on balancing between potential gain of knowledge and suffering of animals used in experimentation. The balancing process is complicated, on the one hand by plurality of views on our duties towards animals, and on the other hand by more recent discussions on uncertainty in the probability of reaching the final aim of the research and problems of translational failure.

The study combines ethical analysis based on a literature review with neuropsychiatry-related preclinical research as a case study.

Based on the analysis and the case study we show that neuropsychiatry-related preclinical research is an especially interesting case from an ethical perspective. The 3R principles (Replacement, Reduction and Refinement) are used to minimize the negative consequences for the animals used in research. However, neuropsychiatric research is characterized by specific challenges in assessing the probability of success of reaching the final aim, due to our limited mechanistic knowledge of human neuropsychiatric illness. Consequently, the translational value of the currently used animal models may be difficult to prove, which undermines the validity of these models and complicated the ethical assessment.

Conclusions

We conclude that a combined approach that deals with both science and the ethical dimensions is necessary to address the problems of validity and translation in neuropsychiatry-related preclinical research. We suggest this approach to comprise first, improved experimental methods, e.g. by using systematic reviews, second, a more patients-based approach that leads to models that reflect interindividual variation better, and third, more interdisciplinary cooperation.

According to current European laws and policies on the use of animals for scientific purposes, animal experimentation is considered ethically acceptable only if it delivers knowledge that weighs up against the suffering of the animals used (EU 2010 [ 1 , 2 ];). However, to make such an assessment is not easy. Debates on the ethical acceptability of animals in research are characterized by plurality and disagreement [ 3 ]. This disagreement finds its origin in different views on the moral position of animals and the value of the aims of the research, but is also due to problems of probability and uncertainty. Each of these aspects have always been complicating factors for an ethical assessment. Research with animals is evaluated before the actual experiment takes place. Therefore, one never can be completely certain about the question whether the direct or final aim will be reached [ 4 ]. This situation has been further complicated by more recent discussions about the quality of the research models used at the translational success of preclinical animal research [ 5 , 6 , 7 , 8 , 9 ].

The aim of this paper is to present and analyse animal use for neuropsychiatry-related research as a case study to show how questions about the value of the animal models used further complicate the ethical assessments. Our reflection consists of three parts. First, we present the background and increasing complexity of the ethical debate on animal research. Second, we show why neuropsychiatry-related research is an interesting case from an ethical perspective. Finally, we aim to show that, both from a normative and a scientific perspective, research quality benefits from ethical reflection.

The ongoing ethical debate: animals as moral subjects

Ethical deliberations in the context of animal research often start with the question whether we should treat animals as moral subjects. If so, animals should be taken into account in our moral reasoning for their own sake. In animal research, we take the interests of the animals into account, as good animal health and welfare can also benefit the research. However, considering animals as moral subjects is taking another step. This moral standing implies that one has direct reasons to take the interests of animals into account rather than only because it coincides or correlates with human interests. Acknowledging that animals are entities that have moral status entails direct implications for our duties towards them. However, even if we agree on that (some) animals have moral status, there is still debate on what it implies in terms of our duties. Some argue that it is morally wrong to take the life of an animal for any reason. Others stress that the most important duty is to prevent suffering. These differences have their origin in the why question, i.e., the various arguments that underlie the claim of animals having moral standing, such as sentience, ability to suffer, higher cognitive abilities, capacity to flourish, sociability and animals being “subjects-of-life” [ 10 , 11 , 12 , 13 ].

Before jumping to the conclusion that there seems to be consensus about the moral position of animals, we note that some expressed clear arguments against the idea of animals having a moral status. They claim that humans do not have any direct moral obligations toward other animals. The arguments for this position are diverse, but some of them refer to the superiority of the human species. The notion that there are empirical differences between species is widely acknowledged, but the superiority view emphasizes the differences between species as morally relevant and as affecting the moral status of humans and other species. This results often in the idea that human preferences are more important than those of other species for the only reason that humans are more important as a species. Without additional morally relevant arguments, this position is flawed, and referred to as ‘speciesism’ [ 14 ]. Singer argues that this position is like racism or sexism, which have been proven to be flawed, as they directly derive normative arguments from empirical differences. Likewise, stressing the empirical difference between humans and non-human animals cannot be the only argument to settle ethical questions of animal use.

Others contrived additional arguments to substantiate the moral difference between animals and humans (cf. [ 15 ]). They emphasize that humans are superior to animals in terms of rationality, ability to communicate, and self-awareness. Consequently, they argue that animals cannot count independently in our moral reasoning. Referring to superior human rationality or moral autonomy is, however, not beyond debate. Authors such as Tom Regan, Peter Singer and Richard Ryder show the complexity of the discussion by introducing the so-called Argument from Marginal Cases [ 16 ] and more recently Horta [ 17 ] used the Argument from Species Overlap. Although human infants and intellectually disabled people may not meet all the cognitive criteria essential to be acknowledged as moral agents, we nonetheless commonly agree that we can have duties towards them, and that it would be morally wrong to conduct harmful experiments on them. If one refers to human rationality as the necessary criterion to enter the moral circle, we still need, out of consistency, additional moral arguments of why we are allowed to experiment on (non-rational) animals.

For this moment, we can conclude that despite the plurality of views, there are strong reasons to take animals into account in our moral reasoning for their own sake, which is also reflected in European and national (e.g. in the Netherlands) legislation [ 18 ].

Ethical assessment of animal testing: a complex task further complicated

If one acknowledges that sentient animals have moral status, this does not immediately imply that one disagrees with the use of animals in experimentation in any situation. Some lines of reasoning do lead to an abolitionist position, but not all ethical positions that acknowledge that animals have moral status exclude justification of using animals for research [ 18 ]. The most common argument to justify the use of animals in research is the expected benefit to humans, but also to animals themselves in veterinary practice. Regardless of the anticipated benefits, replacement, reduction and refinement (the 3R principles, [ 19 ]) are used to minimize the negative consequences. The justification based on expected benefit can also be recognized in the EU directive (EU 2010) that requires a harm-benefit analysis (HBA) for each animal experiment and starts from the assumption that an experiment can only be justified if the expected harm is weighed against the expected benefits. Based on the situation of ongoing animal research one may conclude that that many studies directly or ultimately have important aims. However, the situation is far more complex. First, making a HBA including the assessment of the potential benefits is not easy. There are a number of difficulties related to the aim and the procedure of the analysis. These comprise, for instance, securing transparency in the process and the level of consistency between outcomes of the analysis, while at the same time still allowing room for the dynamics of ethical deliberation [ 20 ]. Furthermore, members of ethical committees are struggling with this task themselves. They often tend to focus on the technical issues, on which one assumes to reach consensus more easily rather than on the ethical questions whether the benefits of the research exceed the expected harm to the animals (cf. [ 21 ]). Second, the complexity on a procedural and practical level can partly be explained by plurality on a theoretical level. The diversity of views cannot be reduced to the textbook distinction between consequentialist and deontological approaches [ 22 ]. The Nuffield Council [ 3 ] also shows that the plurality of theories results in a continuum views, rather than in principled pro or contra positions. Many other approaches, including virtue ethics, care ethics and pragmatism can analyse and deal with moral conflicts between human health and wellbeing and animal pain and suffering. However, they do so in different ways and with different practical consequences. It makes a substantial difference whether the ethical assessment is framed in terms of human and animal welfare or whether it is perceived as a conflict between duties of care in which relations between humans and animals play an important role. In the latter approach, the fact that dogs are often perceived as closer to humans than pigs can be a relevant argument in the assessment, where in a welfare-only approach this would be considered as irrelevant for the moral justification.

However, the third aspect that complicates the ethical assessment is a challenge for a broad range of ethical theories. Each theory that considers animal testing as a moral problem and therefore requires some sort of moral justification has to deal with uncertainty; the uncertainty of the outcome of an experiment, and if it will contribute to its final aim. Therefore, for the ethical justification of research with sentient animals we need to determine the extent to which the use of an animal model delivers useful outcomes, and if it is an efficient way to fulfil our duties towards humans (or other animals) [ 23 ]. We thus need arguments showing a relation between the desired outcome and the suggested research design, as well as arguments showing that there is a reasonable expectation of reaching the (direct or final) aim with the experiment [ 24 ]. This does not only hold for the justification of basic research [ 25 ], it equally is a crucial question for preclinical research. A growing number of publications show that the translational value of animal data is relatively low, i.e., the clinic does not mirror findings in animal experiments (cf. [ 5 , 26 , 27 ]). In the next sections, we focus on neuropsychiatry-related preclinical research as a case study to analyse the impact of the challenges of uncertainty and problems of translation on the ethical assessment.

The relevance of the aim in preclinical research

The ability of an animal model to deliver valid results depends on, among others, adequacy of this model to simulate the phenomena under study, the reliability of the methods and experimental design, staff competence, the quality of the facilities used, and the communication of research results [ 2 , 28 ]. High study quality is essential to the success of an animal experiment and therefore highly relevant for the ethical justification of any animal experiment.

Only experiments that are based on proper scientific reasoning and that use proper methods can deliver reliable results that can function as, metaphorically speaking, a brick in the cathedral of knowledge [ 29 ]. This can be understood as a procedural criterion in the discussion on animal research; the animal experiment is justified as long as it is conducted in a methodologically sound manner [ 3 ]. However, this criterion already includes a normative dimension. It starts in the recognition of the value of knowledge as such [ 30 ] and of the impossibility to predict future implications of any research. Based on these assumptions the procedural criterion can be understood as a sufficient condition to justify research that involves animals, because it ensures studies delivering reliable results. From this perspective, further considerations of the relevance of the research question are not necessary for the justification.

In contrast, others consider that animal use can only be justified if one can prove that a specific study has direct applicability for alleviating human or animal suffering [ 25 ]. As accepting research involving animals is only possible under specific ethical constraints, the relation between the direct and final aim and the used study design becomes pivotal in the question whether we should use animals in scientific research. These considerations are further complicated ‘when animals are used as models for humans, as the question of whether reliable extrapolations can actually be made from one species to the other, needs to be addressed’ ([ 3 ], p. XXI). Before analysing the probability that a study will lead to the aimed result, we need to distinguish between the direct and the final aim.

We define the direct aim as testing of the research hypothesis; e.g. introduction of the independent variable A causes a change in the measurable levels of dependent variable B. At this level, scientific scrutiny is essential. If we focus on the direct aim, one may consider an experiment as ethically acceptable if:

1) the experiment is conducted in a methodologically sound manner,

2) the chosen methodology can answer the research question,

3) the research question could not have been answered without the use of animals,

4) the number of animals used has been reduced to a minimum,

5) any unnecessary suffering of animals was prevented.

The first two points relate to the direct research aim. The remaining three points relate to the minimal ethical consideration on the use of animals: the 3Rs (replacement, reduction, refinement) [ 19 ].

We consider the final aim as the ultimate reason for conducting research activities, e.g. the pursuit of knowledge as a value in its own right or alleviating human suffering. In case of preclinical research of neuropsychiatric disorders, the final aim could be to gain knowledge on human neuropsychiatric disorders (or their selective symptoms) [ 2 , 31 , 32 ]. The ethical assessment of this ultimate aim requires realistically assessing the probability of reaching that final aim. This, however, is complicated, as it will depend on numerous conditions. The most important of these conditions is the translational validity of an animal model, i.e. its ability to accurately and sufficiently represent the condition under research [ 31 ]. Using models that are not valid is scientifically uninformative and morally unjustified [ 33 ]. However, it is difficult to obtain scientific agreement on the translational value of any given animal model (cf. [ 7 ]).

Neuropsychiatry-related research: complexity and uncertainty

Uncertainty on the translational value of models is present in any field of research. However, the extent of uncertainty is especially high in preclinical research of neuropsychiatric disorders. In this section, we elaborate on this claim.

From the methodological perspective, animal models are not simply phenomenological copies of human phenotypes, they are rather complex theoretical constructs which require series of assumptions (e.g., about similarity of neurological systems or the importance of social behaviour). For neuropsychiatric disorders, animal models should be regarded as complex theories ‘about the aetiology and neuronal mediation of psychiatric disorders’ [ 31 ]. Consequently, estimation of the validity and reliability of any animal model benefits from ‘a sound theory about the disorder and the related theories underlying the model’ [ 31 ]. This condition is hard to fulfil for animal models of neuropsychiatric disorders, because neuroscience struggles to create coherent and comprehensive theories on neuropsychiatric disorders at various levels of scientific conceptualization. First, the etiology of neuropsychiatric disorders is poorly known, multifactorial “and/or there is an inability to alter the known etiology of a particular disorder” [ 34 ]. Second, there is a lack of knowledge of pathophysiology of neuropsychiatric disorders [ 35 ]. Third, theories on the etiology of neuropsychiatric disorders are difficult to falsify as it is hardly ever possible to conduct controlled experiments on human subject. Therefore, it is virtually impossible to distinguish between risk factors, triggering factors and resulting symptoms in human studies. Finally, neuropsychiatric disorders are defined by a list of symptoms out of which only some need to be present to diagnose a patient [ 35 ]. However, the symptoms that are not necessarily present in all the patients are often considered as necessary for the validity of new animal models [ 31 ]. Besides, many symptoms that are part of a neuropsychiatric diagnosis are subjective and perspective-dependent [ 36 ]. While patients can report on their emotional status, subjective symptoms cannot be modelled reliably and accurately in animals, thus raising concerns on model validity.

These methodological and conceptual difficulties are recognized. However, they are rarely discussed within the scientific community [ 2 , 37 , 38 ]. The awareness of limitations in current knowledge of the etiology and pathophysiology of neuropsychiatric disorders is even used as an argument to emphasise the importance of conducting animal research. It is argued that because it is virtually impossible to perform controlled experiments of risk factors in humans, and because the etiology is unknown, we are required to use animal models to fulfil our duties towards patients. However, one could equally use the shortage of clinical knowledge as a strong argument to restrict the use of animal models for neuropsychiatric disorders, because the lack of knowledge and falsifiable theories hampers the establishment of models with construct validity [ 23 , 24 , 38 ]. The lack of knowledge on ethiology and pathophysiology also undermine the results obtained from the currently used animal models of neuropsychiatric disease [ 37 , 38 ].

One could still argue that the complexity and related uncertainty described above is not exclusive to neuropsychiatry-related research but that it is an inherent feature of any study using animal models. In biology a considerable continuity in biological (including genetic), anatomical, physiological, neurological, biochemical and pharmacological properties is assumed between animals and humans. If this assumption is true, one can agree that it is possible to e.g. study the dopaminergic system in a mouse brain (e.g. [ 39 , 40 ]) as an approximation of the dopaminergic system in a human brain. In this type of mechanistic research, it is not necessary to postulate that the animal model is a model of a human disorder. Instead, it is a model of human neuroanatomy or biochemistry. However, even this simple logical construct can be questioned. Indiscriminate acceptance of this continuity can be criticised by pointing out differences, and by erroneous predictions based on animal models [ 24 , 41 , 42 ].

We do not consider it helpful for the ethical or the scientific debate to frame the discussion on this debate in an either-or dichotomy, since this often ends in a deadlock that neither improves scientific quality nor the position of the animals. For our current aim, it is not necessary to discuss the validity of animal models in general [ 1 ]. Rather, the validity of any given animal model needs to be evaluated in relation to the specific direct and final research aim [ 38 ]. That condition results in some problems that are specific to neuropsychiatry-related research.

The example of the dopaminergic system describes research of neurobiological processes that are postulated to underlie the pathophysiology of neuropsychiatric illness. This type of animal experimentation is not using an animal model of a neuropsychiatric disorder sensu stricto. The understanding of what an animal model for a neuropsychiatric disorder is, changed over time. According to the previously popular approach, an animal model is valid if and only if it resembles all the symptoms of a given disorder. This method is however losing its support in the scientific community as it becomes obvious that no animal model manages to mimic all aspects of a disorder. Besides, this approach requires assuming that it is possible to evoke states that are comparable to human depression or psychosis in animals. This assumption cannot be tested.

The current approach to preclinical research of neuropsychiatric disorders requires that an animal model resembles part of a psychiatric disorder, e.g., behavioural, cognitive or emotional phenotype [ 43 ]. The resemblance is evaluated based on face validity. This approach can be criticized in two ways. First, it requires the assumption that human and animal experiences are comparable in nature, which was elegantly refuted by Thomas Nagel [ 44 ]. Second, despite the similarities between animals and humans, there is no guarantee that the same mechanism underlies phenotypes that are related to each other based on face validity alone [ 38 ]. As Nestler and Hyman [ 38 ] express it: ‘There is an important chasm between the claim that disruption of some biochemical pathway regulates behaviour and the claim that it models a particular human disorder with useful implications for pathophysiology or treatment development. According to the ‘behavioral common path’ [ 45 ], multiple biological processes take place within the organism which may eventually be reflected in a limited repertoire of behaviours. Therefore, it is not possible to speculate which biological mechanisms underlie the phenotype under observation [ 45 ]. From this perspective, the probability of deducting the biological basis of behavioural manifestations of human neuropsychiatric disorder is low when animal models are based on face validity for the human phenotype under study. These criticisms add an additional level of uncertainty to the use of animal as models of neuropsychiatric disorders.

The uncertainty that is especially present in neuropsychiatry-related preclinical research complicates an ethical evaluation of the use of animals for this field of research. Although the societal relevance of alleviating health and welfare problems related to human neuropsychiatric illness will be commonly acknowledged, the uncertainties with regard to the validity of the models hampers the possible justification of using animals for this type of research. Therefore, reflection on the uncertainties is essential. On the one hand, it is important from an ethical perspective since it touches upon broader questions of how much uncertainty is allowed in ethical reasoning and the conditions of precautionary reasoning (e.g., [ 46 ]). On the other hand, it is essential because if this aspect is ignored it may lead to the use of models with only face validity to answer research questions requiring models with construct validity [ 31 , 38 ]. In contemporary research, a lack of models with construct or predictive validity results in the use of models with only face validity [ 38 ]. Furthermore, reflection regarding clinical facts and the theoretical basis of models is lacking. This leads to a situation in which validity is assumed based on the amount of publications using a certain model or on the lack of other models [ 38 ]. However, this practice does not correspond with the final and direct aims of research. Continuing the use of animal models that lack construct validity may result in weak translational value and poor predictive power for drug effectiveness [ 47 ]. Ultimately this could result in a virtual “standstill” in the process of discovering new psychiatric drugs [ 38 ] accompanied by the unnecessary use of animals for research [ 2 ].

To summarise, a proper ethical evaluation of animal use in neuropsychiatry-related preclinical research is complicated by high levels of uncertainty. Although uncertainty is an inherent part on any scientific endeavour, it elicits specific questions for research on the biological basis of neuropsychiatric disorders. This is the result of our limited knowledge on the human neuropsychiatric illnesses which are being modelled. Consequently, the translational value of some of the currently used animal models may be difficult to prove, but also to debunk, which results in an ethical problem regarding the justification when using these models.

Research on anorexia nervosa (AN) as a case study

We would like to illustrate the above-mentioned situation with a case study. We focus on anorexia nervosa (AN) and the preclinical research on one of its symptoms: high levels of physical activity, which for the purpose of this paper will be called excessive exercise. We selected AN out of personal interest and experience of one of the authors with AN animal models [ 48 , 49 ]. Besides, while the main characteristic of anorexia nervosa, intense fear of gaining weight, cannot be analysed in animal models, several of the symptoms (reduced energy intake and weight loss) can be assessed objectively. Moreover, the ethics of animal models for several other disorders (e.g. schizophrenia, depression, ALS, neuropathic pain and OCD) have previously been discussed ([ 36 ]; Vieira de Castro and Olsson, 2014), while the ethics of AN models has to the best of our knowledge not been specifically assessed before.

Excessive exercise, in combination with other factors, can contribute to the development of AN by facilitating body weight loss [ 50 ]. From this perspective, research on excessive exercise has high clinical relevance, and various experiments tried to establish animal models of this condition. However, several unresolved issues exist on the exact nature and role of excessive exercise in the etiology of AN. First, there is no clear definition of excessive exercise in AN [ 50 , 51 , 52 , 53 , 54 ]. Consequently, it is not possible to create an animal model of excessive exercise with accurate face validity. Second, excessive exercise is only a single aspect of AN, which is neither required nor sufficient for diagnosis [ 55 ]. Third, excessive exercise in AN may be related more to co-morbid disorders than to AN itself; there is e.g. a positive relationship between obsessive-compulsive disorder and excessive exercise in patients with AN [ 56 ]. Fourth, it is unclear if excessive exercise should decrease during the treatment of AN [ 57 , 58 , 59 ]. As animal models are often used to screen for new treatments, the value of an animal model of excessive exercise in AN cannot be established. If one cannot expect a decrease of excessive exercise as a consequence of successful treatment, one cannot use it as a behavioural readout for a pharmacological screening test. One could ask whether we should strive to discover a pharmacological treatment for excessive exercise in the first place as a behavioural intervention may be more appropriate. Fifth, it is not established whether excessive exercise is a premorbid characteristic of AN patients [ 53 , 59 ] or whether it is evoked by an extreme food restriction [ 60 , 61 , 62 , 63 ]. Despite the aetiology not being resolved, animal models of excessive exercise in AN have been created. We will further focus on the so-called activity-based anorexia model (ABA). The ABA model is considered the most promising animal model of AN because of its apparent face, construct and predictive validity [ 64 , 65 ] and one paper even states that it is probably the best animal model within all animal models of human psychiatric illnesses [ 66 ]. Strictly speaking ABA is not a model for AN as a whole, but only for one of its symptoms, namely excessive exercise evoked by food restriction and body weight loss. In the ABA, restricted feeding results in high wheel running activity levels, which lead to a further reduction in body weight and food intake. However, the assumption that the excessive exercise seen in AN is merely a result of body weight loss has not always been confirmed in human research [ 53 , 57 ]. The ABA model was established based on a theory of one specific aetiology of excessive exercise in AN, which was not confirmed in clinical research. If this aetiological theory is correct, the ABA model possesses apparent construct validity. However, one could argue that the face validity of the model is limited at best. It thus is hard to predict to what extent the ABA model could be used to unravel the neurobiological basis of excessive exercise in AN.

Despite the above-mentioned concerns on the use of excessive exercise as a read-out of clinical improvement, the ABA model has been used to test various neuroactive compounds with the aim of finding substances that can decrease the excessive exercise and increase body weight. However, we note that the translational value of the ABA model can be questioned on the basis of available data [ 66 ]. Although various compounds (targeting various brain systems, e.g. dopaminergic, serotonergic, melanocortinergic and opioid systems) decreased activity in the ABA, they were not effective in AN patient treatment [ 66 ]. Furthermore, while leptin levels correlate with physical activity in AN-patients [ 67 ] and leptin injections diminish running wheel activity in the ABA model [ 68 ], these injections also decrease food intake even further and pose a threat to body weight restoration [ 69 , 70 ]. Therefore, one may conclude that the ABA model has limited use in testing compounds which could be used for symptomatic treatment of AN [ 66 ]. Moreover, the ABA model is based on the assumption that it is possible to compare excessive exercise in humans with a specific form of hyperactivity measured in rodents: high running wheel activity. Given the uncertainty of the translational value of the model, this also adds to be careful in choosing the ABA model to answer specific research questions.

These concerns and the conclusion about validity and translatability are not restricted to the ABA model. It also applies to other animal models. Therefore, the challenges cannot be addressed by just choosing another model. The discussion of the ABA model shows general challenges that the field of neuropsychiatry preclinical research is facing. Therefore, the importance of the case study is not limited to the discussed model.

Three possible steps to change and combine science and ethics

The importance of questioning the validity and translational value of animal models is recognized by researchers who strive to improve the existing situation. Proposed solutions target this issue at three levels.

First, to increase reproducibility of results, there are attempts to improve the methodology. That can be pursued in different ways. On the one hand, one can aim to standardize tests between different laboratories, while incorporating standardized variation in the experimental designs to increase external validity. A recent example of this approach is described by Grandjean et al. [ 71 ], who standardised the fMRI analyses for a multi-centre mouse study, maintaining cross-laboratory differences in equipment and procedures. Standardisation between laboratories increases the ability of the animal model to reach the direct aim and reliably address the research hypothesis. However, without external model validity it has only limited effects on reaching the final aim of research if the ultimate reason for conducting a specific research activity is finding an effective treatment for humans. On the other hand, the use of Systematic Reviews (SRs), i.e., in-depth analysis of previously performed experiments, can be essential to increase research quality, and to maximise use of the available data [ 72 , 73 ]. This will not solve the validity problem as such [ 74 ] but can help to trace pitfalls and provide evidence about the (lack of) translational value of animal models [ 75 ] and enable to estimate the evidential weight of animal models [ 76 , 77 , 78 ].

Second, it is important to acknowledge that an experimental animal is not a patient. That may seem a truism. However, research models always have to balance between the clinical heterogeneity due to the complexity of the individual patients and the need to test with standardised animals under standardised conditions. The arguments of feasibility and replicability lead to a demand for standardisation, whereas successful translation to the variety of patients asks for incorporation of complexity and diversity. This can be called the “standardisation-translation paradox” [ 79 ]. To tackle this paradox, it is essential to start designing research models incorporating the complexity of the patient, including e.g. specific genotypes and personal histories. Animal models should reflect the variation between patients to increase external validity; testing should be performed in e.g. young and old animals of both sexes with different genetic backgrounds as far as these characteristics are relevant to the patient population. Note that while we encourage increasing the complexity of the modelled patient , we do see potential value in reducing the complexity of the modelled pathological process and assessing endophenotypes reflecting only part of a complex disease, as advocated by e.g. Cryan and Slattery [ 80 ]. Tackling the standardisation-translation paradox also requires reversed translation: the research question should be formulated from a clinical context and then translated into a specific question that can be addressed with an (animal) experiment. In our experience, many animal studies start with a question that may seem clinically relevant and start with an existing animal model that has been used in the laboratory before. Furthermore, tackling this paradox asks for standardised variation. To mimic the patient in preclinical research we have to incorporate the variation we find in the patients into our research in a standardized manner. Relevant variation (e.g., gender, genetic background) has to be incorporated into preclinical research. In practice, this recognition of clinical heterogeneity within mental disorders and their comorbidities caused a shift from modelling mental illness to modelling phenotypes. Validity and translational value need to be examined for each phenotypic model to the same extent as before for the ‘full disease models’. This requires that scientists in the field of neuropsychiatric disorders more honestly assess the potential benefits of their research efforts a priori. This task is challenging, but necessary to ethically justify the use of animal experimentation. Furthermore, while it is not as commonly performed by ethical review boards as we would have hoped (Vieira de Castro and Olsson, 2014), it is possible. There are guidelines to aid estimating the possible benefits and harms of the use of any given animal model, for example the guidelines proposed by the Federation of European Laboratory Animal Science Associations ([ 28 ], Table 2). However, the available guidelines hardly address the question of transferring knowledge across species, which should, in our opinion, be added to allow for honest assessment of the potential benefits and harms.

Third, more collaboration in and integration of the research chain is needed. If innovation with respect to validity and translation remains at the level of individual research groups, not much will happen. This is not due to incompetence or indifference, but the development of new models is not an easy task and in practice easily hampered by processes within the scientific community. Creating a new animal (free) model is a time consuming and unrewarding task. It is challenging to validate a new model to the extent that satisfies the scientific community and the legal guidelines. Therefore, researchers preferably use established animal models, even if their validity is limited. This strategy maintains status quo and discourages creative solutions. Creating a new animal (free) model with good translational value and validity is further complicated by the limited knowledge of etiology and pathophysiology of neuropsychiatric disorders discussed above. This shows the need of more consorted action. It requires improved cooperation between clinical and preclinical researchers, but also journals and legislators. Although the expertise to innovate is at the level of the individual researchers, the responsibility is shared and cannot be limited to this group of people.

Additionally, addressing problems of validity and translation requires input from various disciplines. Given the transdisciplinary nature of current research consortia this may not seem a real challenge. However, difference in the basic assumptions between science and ethics may seriously complicate model development in the field of neuropsychiatric disorders in three ways. Firstly, scientists conducting (neuro)-psychiatric clinical and preclinical research do not share a single view on the nature of neuropsychiatric disorders; they have different implicit and explicit biological, anthropological and philosophical theories on disease pathology, causality and the mind-body dualism. This hampers collaboration and efforts of creating clear guidelines for preclinical research. Furthermore, not all neuropsychiatry-related preclinical research has the alleviation of human suffering as its final aim, the aim may be restricted to advancing knowledge. For example, it could aim to understand neuronal systems which might be involved in neuropsychiatric disorders and testing of new therapeutic agents [ 2 ].

Finally, also for researchers in this field holds that there is a fundamental plurality of views on the moral status of animals and the relevance of ethics. This combination creates a complex matrix of possible positions in the ethical justification, recognition of ethical dilemmas and scope of solutions that are considered acceptable. It requires a level of reflection and openness to the normative and scientific assumptions that goes beyond the old-fashioned views of ethical dilemmas as subjective [ 81 ] and irresolvable. We agree with Gluck and Bell [ 23 ] that researchers cannot leave consideration of the moral dilemmas to others, as this may lead to scientific practice based on “questionable prejudices”. We consider it to be the professional responsibility of researchers to work on the translatability of results, and to consider the ethical dilemmas resulting from epistemological uncertainties. This is not only a theoretical ‘ought’; recent examples (cf. [ 82 ]) show that it is possible to combine the preclinical and clinical context with attention to the ethical dimension to discuss the translational neuroscience.

It is important to stress that from this perspective, ethical reflection is not an add-on to the science debate, but research quality benefits from ethical reflection. This, however starts from the notion that ethics in the context of animal research cannot be reduced to the ethical principles of reducing harm and applying the 3Rs. These two are important, but insufficient principles to discuss the quality of the used models and to explore innovative research methods. Ethical deliberation in the context of animal includes also the principles of transparency and consistency. This means, for instance, that the steps in the process of choosing a research model must be verifiable and open to discussion with an interdisciplinary group of peers. Furthermore, ethical reflection enables to deal with problems of uncertainty and the evaluation of benefits (cf. [ 83 ]. This is not only relevant in the ethical assessment in the context of a harm-benefit analysis, but also in defining what model should be used for what aim. The choice of a research model comes with questions of uncertainty and probability about interspecies comparison and linked to views on the direct and final aim of the research. Both dimensions include a normative component that requires ethical reflection (cf. [ 4 , 84 ].). Therefore, ethics in the context of animal research should have wider focus than on animal protection only and can in this way contribute to the quality of research.

The aim of this paper was to present and analyse animal use for preclinical research on neuropsychiatric disorders as a moral problem which demands combined ethical reasoning and logical evaluation of scientific practice. We conclude that this moral problem is specifically complicated in neuropsychiatry-related research, due to the limited knowledge on neuropsychiatric disorders in humans and resulting in difficulties with establishing valid animal models for these disorders. Consequently, preclinical research is characterized by the frequent use of animal models which do not possesses sufficient validity to reach the direct or final aim of research. This raises an ethical concern, because current policies require that ethical justification presumes the probable gains for humans outweighing the suffering experienced by animals. The problem of translation frustrates this justification. Therefore, we proposed three steps to address the problems of validity and translation: optimising the methods, incorporating the complexity of the patients into the models, and increased and collaboration within the research chain. This entails a scrupulous analysis of currently used animal models to improve the applicability of research. In this process systematic reviews can provide relevant information. Furthermore, it is essential to start with the clinical heterogeneity and design research models that are better capable to mimic the complexity of the patient. This requires reversed translation: the research question should be formulated from a clinical context and then translated into a specific question that can be addressed with an (animal) experiment, rather than to start with the existing animal models as the golden standard. This task is challenging, but necessary to ethically justify the use of animal.

Finally, we proposed that the previous steps require more and better cooperation between partners in the research chain from bench to bedside and between the relevant disciplines. This is not only a matter of improved organization and procedures, but also of attitude. Innovation that leads to enhanced validity and translation of models used in neuropsychiatry-related preclinical research is only possible in an open dialogue about the aims of the research and the relevant models, in awareness of the plurality of views on both the scientific and ethical level. For ethics this entails that ethics in the context of animal research cannot be reduced to the ethical principles of reducing harm and applying the 3Rs. To contribute to the quality of animal research is equally should deal with broader issues such as uncertainty, evaluation of benefits and transparency. The combination of ethics and science in this discussion is not a detour but helps to get a grip on the complexity of the issues at stake. It can improve the clarity of the discussion by helping to distinguish between questions that have their origin in ethical viewpoints from those that relate to the scientific validity of the models. Furthermore, it helps to combine firm knowledge of human psychiatric disorders with the relevant values and interest at stake to come to an honest evaluation of currently available preclinical models. It is important that national and international research societies put this combined approach to the challenge of translation on the agenda more prominently.

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Abbreviations

Principles of replacement, reduction, refinement

Activity-based anorexia

Anorexia Nervosa

Harm-benefit analysis

Systematic Review

Shelley C. Why test animals to treat humans? On the validity of animal models. Stud Hist Phil Biol Biomed Sci. 2010;41:292–9.

Article   Google Scholar  

Vieira de Castro AC, Olsson IAS. Does the Goal Justify the Methods? Harm and Benefit in Neuroscience Research Using Animals. Curr Top Behav Neurosci. 2015;19:47–78. https://doi.org/10.1007/7854_2014_319 .

Nuffield Council. Nuffield Council on Bioethics. In: The ethics of research involving animals; 2005.

Google Scholar  

Meijboom F. Applying Ethical Thinking and Social Relevance. In H. Röcklinsberg, M. Gjerris, & I. Olsson (Authors), Animal Ethics in Animal Research. Cambridge: Cambridge University Press; 2017. pp. 41–67 doi: https://doi.org/10.1017/9781108354882.005 .

Ioannidis JPA, Greenland S, Hlatky MA, Khoury MJ, Macleod MR, Moher D, Schulz KF, Tibshirani R. Increasing value and reducing waste in research design, conduct, and analysis. Lancet. 2014;383:166–75.

Lowenstein PR, Castro MG. Uncertainty in the translation of preclinical experiments to clinical trials. Why do Most phase III clinical trials fail? Curr Gene Ther. 2009;9(5):368–74.

Philips T, Rothstein JD, Pouladi MA. Preclinical models: Needed in translation? A Pro/Con debate. Mov Disord. 2014;29(11):1391–6. https://doi.org/10.1002/mds.26010 .

Van der Worp HB, Howells DW, Sena ES, Porritt MJ, Rewell S, et al. Can animal models of disease reliably inform human studies? PLoS Med. 2010;7(3):e1000245. https://doi.org/10.1371/journal.pmed.1000245 .

Yu D. Translational research: current status, challenges and future strategies. Am J Transl Res. 2011;3:422–33.

Droege P, Braithwaite VA. A framework for investigating animal consciousness. Curr Top Behav Neurosci. 2015;19:79–98.

Regan T. The case of animal rights. Berkeley: University of California Press; 1983.

Rollin BE. Animal rights and human morality. New York: Prometheus Books; 1992.

Warren MA. Moral status: obligations to persons and other living things. Oxford: Clarendon; 1997.

Singer P. Animal liberation. New York: Random House; 1990.

Carruthers P. The animals issue: moral theory in practice. Cambridge: Cambridge UP; 1992.

Book   Google Scholar  

Dombrowski D. Babies and beasts: the argument from marginal cases. Champaign: University of Illinois Press; 1997.

Horta O. The Scope of the Argument from Species Overlap. Journal of Applied Philosophy. 2014;31(2):142–54.

Röcklinsberg HM, Gjerris M, Olsson IAS. Animal ethics in animal research. Cambridge: Cambridge University Press; 2017.

Russell WMS, Burch RL. The principles of humane experimental technique. Baltimore: Johns Hopkins University; 2013.

Grimm H, Olsson IAS, Sandøe P. Harm–benefit analysis – what is the added value? A review of alternative strategies for weighing harms and benefits as part of the assessment of animal research, Lab Anim 2018. https://doi.org/ https://doi.org/10.1177/0023677218783004 .

Ideland M. Different views on ethics: how animal ethics is situated in a committee culture. J Med Ethics. 2009;35:258–61.

Spielthenner G. Consequentialism or deontology? Philosophia. 2005;33:217–35.

Gluck JP, Bell J. Ethical issues in the use of animals in biomedical and psychopharmocological research. Psychopharmacology. 2003;171:6–12.

Shanks N, Greek R, Greek J. Are animal models predictive for humans? Philos Ethics Humanit Med. 2009;4:2.

Greek R, Greek J. Is the use of sentient animals in basic research justifiable? Philos Ethics Humanit Med. 2010;5:14. https://doi.org/10.1186/1747-5341-5-14 .

Leenaars CHC, Kouwenaar C, Stafleu FR, Bleich A, Ritskes-Hoitinga M, De Vries RBM, Meijboom FLB. Animal to human translation: a systematic scoping review of reported concordance rates. J Transl Med 2019; 17:223, https://doi.org/ https://doi.org/10.1186/s12967-019-1976-2 .

Pound P, Bracken MB. Is animal research sufficiently evidence based to be a cornerstone of biomedical research? BMJ. 2014;348:g3387.4.

Smith JA, Van den Broek FAR, Martorell JC, et al. Principles and practice in ethical review of animal experiments across Europe: summary of the report of a FELASA working group on ethical evaluation of animal experiments. Lab Anim. 2007;41:143–60.

Shepard HA. Basic research and the social system of pure science. Philos Sci. 1956;23:48–57.

Pritchard D, Turri J. The value of knowledge. in: The Stanford Encyclopedia of Philosophy (Winter 2012 Edition), Zalta, E.N. (Ed.) 2012. http://plato.stanford.edu/archives/win2012/entries/knowledge-value/

Sarter M, Bruno JP. Animal models in biological psychiatry. In: D'Haenen H, den Boer JA, Willner P, editors. Biological psychiatry. Chichester: Wiley; 2002. p. 47–79.

Van der Staay FJ. Animal models of behavioral dysfunctions: basic concepts and classifications, and an evaluation strategy. Brain Res Rev. 2006;52:131–59.

LaFollette H, Shanks N. Brute Science: Dilemmas of Animal Experimentation. New York: Routedge; 1996.

Satcher D. Mental health: a report of the surgeon general--executive summary. Prof Psychol Res Pract. 2000;31:5–13.

Cuthbert BN, Insel TR. Toward the future of psychiatric diagnosis: the seven pillars of RDoC. BMC Med. 2013;11:126. https://doi.org/10.1186/1741-7015-11-126 .

Rollin MD, Rollin BE. Crazy like a fox. Validity and ethics of animal models of human psychiatric disease. Camb Q Healthc Ethics. 2014;23(2):140–51. https://doi.org/10.1017/S0963180113000674 .

Hyman SE. The diagnosis of mental disorders: the problem of reification. Annu Rev Clin Psychol. 2010;6:155–79.

Nestler EJ, Hyman SE. Animal models of neuropsychiatric disorders. Nat Neurosci. 2010;13:1161–9. https://doi.org/10.1038/nn.2647 .

Ihalainen JA, Riekkinen P Jr, Feenstra MG. Comparison of dopamine and noradrenaline release in mouse prefrontal cortex, striatum and hippocampus using microdialysis. Neurosci Lett. 1999;277(2):71–4.

Menon JML, Nolten C, et al. Brain microdialysate monoamines in relation to circadian rhythms, sleep, and sleep deprivation - a systematic review, network meta-analysis, and new primary data. J Circadian Rhythms. 2019;17:1. https://doi.org/10.5334/jcr.174 .

Greek J, Shanks N. Thoughts on animal models for human disease and treatment. J Am Vet Med Assoc. 2009;235:363. https://doi.org/10.2460/javma.235.4.363 .

Greek R, Rice MJ. Animal models and conserved processes. Theor Biol Med Model. 2012;9:40.

Geyer MA, Markou A. Animal models of psychiatric disorders. In: Bloom FE, Kupfer DJ, editors. Psychopharmacology: the fourth generation of progress. New York: Raven; 1995. p. 787–98.

Nagel T. What is it like to be a bat? In: The Philosophical Review; 1974.

Sherwin CM. Voluntary wheel running: a review and novel interpretation. Anim Behav. 1998;56:11–27.

Renn O. Risk governance: coping with uncertainty in a complex world. London: Earthscan; 2008.

Markou A, Chiamulera C, Geyer MA, et al. Removing obstacles in neuroscience drug discovery: the future path for animal models. Neuropsychopharmacology. 2009;34:74–89. https://doi.org/10.1038/npp.2008.173 .

Kostrzewa E, Kas MJ. The use of mouse models to unravel genetic architecture of physical activity: a review. Genes Brain Behav. 2014;13(1):87–103. https://doi.org/10.1111/gbb.12091 .

van Gestel MA, Kostrzewa E, Adan RA, Janhunen SK. Pharmacological manipulations in animal models of anorexia and binge eating in relation to humans. Br J Pharmacol. 2014;171(20):4767–84. https://doi.org/10.1111/bph.12789 .

Hechle T, Beumont P, Marks P, Touyz S. How do clinical specialists understand the role of physical activity in eating disorders? Eur Eat Disord Rev. 2005;13:125–32.

Alberti M, Galvani C, El GM, et al. Assessment of physical activity in anorexia nervosa and treatment outcome. Med Sci Sports Exerc. 2013;45:1643–8. https://doi.org/10.1249/MSS.0b013e31828e8f07 .

Beumont PJ, Arthur B, Russell JD, Touyz SW. Excessive physical activity in dieting disorder patients: proposals for a supervised exercise program. Int J Eat Disord. 1994;15:21–36.

Davis C, Kennedy SH, Ravelski E, Dionne M. The role of physical activity in the development and maintenance of eating disorders. Psychol Med. 1994;24:957–67.

Mond JM, Hay PJ, Rodgers B, Owen C. An update on the definition of “excessive exercise” in eating disorders research. Int J Eat Disord. 2006;39:147–53.

American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC: American Psychiatric Association Publishing; 2013.

Young S, Rhodes P, Touyz S, Hay P. The relationship between obsessive-compulsive personality disorder traits, obsessive-compulsive disorder and excessive exercise in patients with anorexia nervosa: a systematic review. J Eat Disord. 2013;2:1–16. https://doi.org/10.1186/2050-2974-1-16 .

Bratland-Sanda S, Sundgot-Borgen J, Øyvind R, et al. “I’m not physically active - I only go for walks”: physical activity in patients with longstanding eating disorders. Int J Eat Disord. 2010;43:88–92. https://doi.org/10.1002/eat.20753 .

Inoko K, Nishizono-Maher A, Ishii K, Osawa M. Effect of medical treatments on psychiatric symptoms in children with anorexia nervosa. Pediatr Int. 2005;47:326–8.

Kron L, Katz JL, Gorzynski G, Weiner H. Hyperactivity in anorexia-nervosa - fundamental clinical feature. Compr Psychiatry. 1978;19:433–40.

Epling WF, Pierce WD. Solving the anorexia puzzle - a scientific approach. Toronto: Hogrefe & Huber; 1992.

Holtkamp K, Hebebrand J, Herpertz-Dahlmann B. The contribution of anxiety and food restriction on physical activity levels in acute anorexia nervosa. Int J Eat Disord. 2004;36:163–71.

Pierce WD, Epling WF, Dews PB, et al. Activity anorexia: an interplay between basic and applied behavior analysis. Behav Anal. 1994;17:7–23.

Sodersten P, Bergh C, Zandian M. Understanding eating disorders. Horm Behav. 2006;50:572–8.

Casper RC, Sullivan EL, Tecott L. Relevance of animal models to human eating disorders and obesity. Psychopharmacology. 2008;199:313–29. https://doi.org/10.1007/s00213-008-1102-2 .

Rieg TS. Validity criteria for animal models of anorexia nervosa involving activity. In: Epling WF, Pierce WD, editors. Activity Anorexia: Theory, Research, and Treatment: Psychology Press; 2013.

Gutierrez E. A rat in the labyrinth of anorexia nervosa: contributions of the activity-based anorexia rodent model to the understanding of anorexia nervosa. Int J Eat Disord. 2013;46:289–301. https://doi.org/10.1002/eat.22095 .

Holtkamp K, Herpertz-Dahlmann B, Hebebrand K, et al. Physical activity and restlessness correlate with leptin levels in patients with adolescent anorexia nervosa. Biol Psychiatry. 2006;60:311–3.

Exner C, Hebebrand J, Remschmidt H, et al. Leptin suppresses semi-starvation induced hyperactivity in rats: implications for anorexia nervosa. Mol Psychiatry. 2000;5:476–81.

Hillebrand J, Koeners M, Derijke C, et al. Leptin treatment in activity-based anorexia. Biol Psychiatry. 2005;58:165–71.

Van Elburg AA, Kas MJ, Hillebrand JJ, et al. The impact of hyperactivity and leptin on recovery from anorexia nervosa. J Neural Transm. 2007;114:1233–7.

Grandjean J, Canella C, et al. Common functional networks in the mouse brain revealed by multi-Centre resting-state fMRI analysis. Neuroimage. 2019;205:116278. https://doi.org/10.1016/j.neuroimage.2019.116278 .

Green S. Medical progress depends on animal models-doesn’t it? J R Soc Med. 2008;101:220–1.

Hooijmans CR, Ritskes-Hoitinga M. Progress in using systematic reviews of animal studies to improve translational research. PLoS Med. 2013;10(7):e1001482.

Henderson VC, Kimmelman J, Fergusson D, Grimshaw JM, Hackam DG. Threats to validity in the design and conduct of preclinical efficacy studies: a systematic review of guidelines for in vivo animal experiments. PLoS Med. 2013;10(7):e1001489 Epub 2013/08/13. pmid: 23935460 .

Hartung T. Food for thought look Back in anger – what clinical studies tell us about preclinical work. ALTEX. 2013;30:275–91.

Matthews RA. Medical progress depends on animal models - doesn't it? J R Soc Med. 2008;101(2):95–8. https://doi.org/10.1258/jrsm.2007.070164 .

Mignini LE, Khan KS. Methodological quality of systematic reviews of animal studies: a survey of reviews of basic research. BMC Med Res Methodol. 2006;6:10.

Sandercock P, Roberts I. Systematic reviews of animal experiments. Lancet. 2002;360:586.

Stafleu FR, Leenaars CHC, Coenen de Roo CJJ, Ritskes-Hoitinga M, Meijboom FLB. The translation-standardisation paradox: Translational strategies to tackle it New horizons in translational medicine 2016; 3: 96.

Cryan JF, Slattery DA. Animal models of mood disorders: recent developments. Curr Opin Psychiatry. 2007;20(1):1–7.

Burkhardt J. Scientific values and moral education in the teaching of science. Perspect Sci. 1999;7:87–110.

Yarborough M, Bredenoord A, D’Abramo F, Joyce NC, Kimmelman J, Ogbogu, U, Sena, E., Strech, D., Dirnagl U. The bench is closer to the bedside than we think: Uncovering the ethical ties between preclinical researchers in translational neuroscience and patients in clinical trials. PLOS Biology, 2018; 16/6: e2006343. https://doi.org/ https://doi.org/10.1371/journal.pbio.2006343 .

Kimmelman J, London AJ. Predicting harms and benefits in translational trials: ethics, evidence, and uncertainty. PLoS Med 2011; 8(3): e1001010. https://doi.org/ https://doi.org/10.1371/journal.pmed.1001010 .

Sandøe P, Forkman B, Christiansen SB. Scientific uncertainty - how should it be handled in relation to scientific advice regarding animal welfare issues? Anim Welf. 2004;13:S121–6.

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The authors thank Joachim Nieuwland and the reviews for their valuable comments on previous drafts of this manuscript.

This paper is based on research funded by the Netherlands Organisation for Scientific Research (NWO) entitled “From animal model to translational strategy. On the ethical, scientific and institutional problems related to innovations in bio-medical animal research” (NWO#313–99-310).

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Meijboom, F.L.B., Kostrzewa, E. & Leenaars, C.H.C. Joining forces: the need to combine science and ethics to address problems of validity and translation in neuropsychiatry research using animal models. Philos Ethics Humanit Med 15 , 1 (2020). https://doi.org/10.1186/s13010-019-0085-4

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DOI : https://doi.org/10.1186/s13010-019-0085-4

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In This Article Expand or collapse the "in this article" section Animal Rights

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Animal Rights by Mark Rowlands LAST REVIEWED: 23 June 2023 LAST MODIFIED: 19 December 2012 DOI: 10.1093/obo/9780195396577-0124

The expression “animal rights” is employed in two different ways: one broad, the other narrow. When employed in the broad sense—animal rights with a small “r”—the claim that animals possess rights is used as a way of asserting that animals have moral standing: that they are morally considerable , the legitimate objects of moral concern. Even moral theories that are officially hostile to the concept of rights can accept that animals have rights in this sense. Thus, Jeremy Bentham, the founder of utilitarianism, described the idea of rights as “nonsense” but nevertheless argued that animals possess moral standing. And although subsequent utilitarians have generally inherited this antipathy toward the concept of rights, it was utilitarianism that underpinned Peter Singer’s ( Singer 1975 , cited under Introductory Works , the Basic Argument , and Utilitarianism and Animals ) seminal defense of the moral claims of animals. Thus, Singer, certainly in the minds of the general public, is associated with the idea of animal rights even though the moral theory he deploys is officially hostile to the concept of rights. The broad sense of animal rights is, therefore, a very loose sense, and the area of inquiry might instead be labeled “animal ethics.” In a stronger sense—animal rights with a capital “R”—the claim that animals possess rights is restricted to specific moral theories that endorse both the moral claims of animals and the apparatus of moral rights. In particular, the claim is strongly associated with the deontological framework developed by Tom Regan (see Animals and Natural Rights ), and also with certain contractualist approaches to understanding the rights of animals (see Contractualism and Animals ). This bibliography encompasses animal rights in the broad sense of animal ethics. It focuses on theoretical developments in animal ethics. Tracing the practical implications of each theory or tradition for issues such animal husbandry, experimentation, hunting and other blood sports, zoos, the keeping of pets, and so on has proved to be not only important in its own right but also a significant component in the overall theoretical elaboration of each tradition. Practical work is cited, and practical issues discussed, only to the extent they have impact on the theoretical frameworks.

There are numerous introductions to animal ethics. These may vary in their level of theoretical commitment or orientation. For example, Rowlands 2002 develops its case from a broadly contractualist perspective. The argument of Rachels 1999 is developed in the context of evolutionary theory. Francione 2000 , however, bases its case on inconsistencies in our commonsense attitudes toward animals. The works below are classified as introductions because they deal with the issue of animal ethics in a general way and are written for those with no prior acquaintance with this topic. DeGrazia 2002 and Taylor 2003 are very good examples of this genre, and even though Peter Singer’s position ( Singer 1975 ) is officially utilitarian, this plays no overt or essential role in the development of his arguments. Garner 2005 is a well-written and useful overview of the various positions that fall under the animal rights rubric.

DeGrazia, David. Animal Rights: A Very Short Introduction . New York: Oxford University Press, 2002.

It does what it says on the cover: it provides a lucid, well-written, and very short introduction to the idea of animal rights.

Francione, Gary. Introduction to Animal Rights: Your Child or the Dog? Philadelphia: Temple University Press, 2000.

This introduction, from the leading proponent of the “leave them alone” stance, takes as its point of departure the inconsistencies in our moral attitudes about animals and builds an argument on that basis.

Garner, Robert. Animal Ethics . Cambridge, UK: Polity, 2005.

A useful guide to the current state of play in the animal rights debate. Garner writes clearly, identifies the major issues, and makes some interesting suggestions about how to think about them.

Rachels, James. Created from Animals: The Moral Implications of Darwinism . New York: Oxford University Press, 1999.

Lucid and well-argued case for animal rights grounded in evolutionary theory. Human moral exceptionalism is incompatible with evolutionary theory.

Rowlands, Mark. Animals Like Us . London: Verso, 2002.

A combination of moral theory (of a broadly contractualist orientation) and a detailed discussion of practical issues, including using animals for food, experimenting on animals, hunting, companion animals, and zoos. There is also a discussion of the harm of death as it applies to humans and animals.

Singer, Peter. Animal Liberation . New York: New York Review of Books and Random House, 1975.

This book (arguably) initiated the contemporary discussion of the moral claims of animals and is still essential reading after all these years. In this book, Singer’s utilitarianism is sufficiently submerged to make this a general introduction to thinking about animals in a moral way. Discusses the ethics of eating animals and experimenting on them in lucid and compelling language.

Taylor, Angus. Animals and Ethics: An Overview of the Philosophical Debate . Peterborough, Canada: Broadview, 2003.

Taylor traces the animal rights debate back to its roots in Aristotle and Darwin, and carefully examines the relevant contemporary theories.

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SteelSnowflake

Exploring the ethical implications of descartes, kant, and darwin on our food choices, introduction: the diner's dilemma.

People love their pets and their cheeseburgers. They also hate dwelling on the irreconcilable moral contradictions hidden in those two passions. Lucky for them, the system is set up so they don't have to dwell on it too much. Who would have thought the essential act of eating meat was so morally fraught? And who would have thought such misery could happen in our progressive age?

I want to explore animal ethics and philosophy in the context of three influential thinkers. I'll argue that today's mealtime morality rests on three philosophical pillars: a Cartesian, a Kantian, and a Darwinian.

Descartes' philosophy anticipated factory farming. Here animals were little more than soulless automatons, forever denied ethical consideration. He dismissed them as fleshy machines unable to experience pain or suffering. Herein lies the origins of the modern CAFO (Concentrated Animal Feeding Operation) and all the horrors it inflicts on the sentient critters destined to be our food. This is the first pillar.

Kant offers the second. He highlights our contradictory and hypocritical attitude toward the animals we eat. We adore some while eating others raised in those hellish CAFOs. Billions of livestock like cattle, pigs, and chickens suffer and die every year, leading short lives of windowless misery for the consumer's dining pleasure. Yet we treat dogs and cats like family (sometimes even better), giving them names and loving them for their unique personalities. We deeply care for them and grieve when they are gone.

Finally, Darwin's theory of evolution opened up a third way, setting the stage for today's animal rights movement. He revealed the evolutionary similarities between homo sapiens and other life. His most significant revelation was to prove we're not created in God's image but are merely one branch on an evolutionary tree of life.

If this is true, no absolute separation exists between man and beast, only continuities. We are all animals, different in many ways but ultimately comprised of the same stuff. Humans share identical biological characteristics as other animals, such as the ability to experience pain and suffering. This is key.

Viewed only online, our culture appears as a schizoid mix of gooey compassion for our furry little companions and all the adorably human-like things they do. So cute! So relatable! And indeed, they are.

Yet working parallel to all this is a relentless appetite that piteously devours animal flesh without a second thought. This flesh was once as adorable as our kittens and puppies and bunnies. But there is a difference. Before becoming our food, they live far from our empathetic gaze, and so end up invisible abstractions. That this is all intentional fascinates me, as do the contradictions inherent in a system that allows such compartmentalized compassion to exist alongside such remorseless cruelty.

That's what I'll explore below.

Descartes: Origins of the Modern Cartesian Model

René Descartes is most famous as one of the founders of modern philosophy. He also infamously nailed the paws of his wife’s dog to a board to dissect it alive. All in the name of science! According to him, the dog’s cries were no different than the springs and wheels of a clock automatically reacting when dismantled (Joy 109). He acknowledged that animals were alive and experienced sensations. “For I do not deny that any animal has life – which, I claim, consists only in the heat of the heart” (Descartes 175).

However, he rejected that they perceive pain or engage in rational thought. On the contrary, they existed as little more than mechanical automatons incapable of experiencing pain (174). He took it a step further, stating only a mind with an intellect could think. If this were not true, we would not have a will; without that, a rational being could not exist. Will, reasoning, and intelligence set humans apart in the Cartesian worldview (Broughton 408).

This division left everything else excluded from ethical consideration. Descartes thus contradicts the intuitions that tell us this is otherwise. But those intuitions only work when we can interact directly with animals. When we don't interact, or can't, then the cold Cartesian worldview can flourish, if such a word can be used to describe what goes on in factory farms.

In Omnivore's Dilemma , Michael Pollan comments on the moral aspects of factory farmed livestock.

"It is not easy to draw lines between pain and suffering in a modern egg or hog operation. These are places where the subtleties of moral philosophy and animal cognition mean less than nothing, indeed where everything we’ve learned about animals at least since Darwin has simply been…put aside. To visit a modern Concentrated Animal Feeding Operation (CAFO) is to enter a world that for all its technological sophistication is still designed on seventeenth-century Cartesian principles: animals are treated as machines – “production units” – incapable of feeling pain. Since no one can believe this anymore, industrial animal agriculture depends on a suspension of disbelief on the part of the people who operate it and a willingness to avert one’s eyes on the part of everyone else" (Pollan 317).

Pollan is right to compare the French philosopher and factory farming. The image of the efficient mechanical factory and animals treated as production units takes us back to Descartes and his wife’s dog. Descartes argued that if animals cannot experience pain, we can ignore the most basic considerations for their welfare. This synchs up quite nicely with modern capitalism. Animal welfare is secondary to profit. Flesh becomes just another product the factory produces.

Market demands for affordable meat and dairy mean ethical considerations for those living production units are set aside to keep grocery store shelves stocked. The Cartesian ideology offers consumers the cognitive framework needed to set aside sentimentality in the name of mass production. "Well, no big deal since they don't suffer anyway. Let's have some more bacon. Yum,"

Peter Singer argued, “The core issue is the commercial pressures that exist in a competitive market system in which animals are items of property, and the conditions in which they are kept are not regulated by federal or state animal-welfare law” (Singer, The Ethics 55).

Worldwide, factory farms slaughter over 70 billion animals annually. Getting enormous quantities of meat and dairy to market as cheaply as possible means most livestock leads short, crowded lives of misery. It is standard industry practice for chickens to have their beaks cut and pigs to have their tails docked to prevent injuring each other. Why do they hurt each other? Because of the stress of living in dark, crowded conditions from the day they are born until the day they die.

Melanie Joy states, “From a profit standpoint, animal welfare is a barrier to profit, as it costs less to mass-produce animals and discard those who die prematurely than it does to care for them adequately ” (Joy 39).

The Cartesian model, as practiced in agribusiness and medical labs over the last three-quarters of a century, gained a veneer of scientific credibility thanks to the strong influence of B.F. Skinner’s behavioral psychology. Skinner’s ideas represented an updated version of Descartes’ mechanistic view of animal consciousness.

According to Behaviorism, animals (and people) react to environmental stimuli, and that's it. In this model, anthropomorphizing their behavior allowed subjective bias to creep in, which could compromise objective research.

The result was the banishment of descriptive language that seemed to anthropomorphize test subjects like rats, rabbits, and monkeys. By rejecting anthropocentric descriptors to describe observed animal phenomena like emotion, empathy, and sensitivity, science set up cognitive and semantic barriers reinforcing Cartesian indifference.

In The Better Angels of Our Nature , Steven Pinker relates with a guilty conscience about his time as an assistant in a research lab that tested Skinner’s theories of operant conditioning.

"To motivate the animals to work for food, we starved them to 80 percent of their free-feeding weight, which in a small animal means a state of gnawing hunger. In the lab next door, pigeons were shocked through beaded key chains that were fastened around the base of their wings; I saw that the chains had worn right through to their skin, exposing the muscle below. In another lab, rats were shocked through safety pins that pierced the skin of their chests. In one experiment on endorphins, animals were given unavoidable shocks described in the paper as “extremely intense, just subtetanizing” – that is, just short of the point where the animal's muscles would seize up in a state of tetanus " (Pinker 455).

Pinker finishes this disturbing anecdote by noting how one of his fellow researchers sometimes expressed anger by picking up the nearest rat and throwing it against the wall (455).

Likewise, Michael Shermer relates a story of his time in a lab. His job was disposing of the lab rats that were not needed anymore. Of course, by then, Shermer had named some of the rats and found the prospect of killing them unappealing.

“But then the experiment is over and the time comes to dispose of the subjects, which in the case of the rats was done by…I can barely type the words…gassing them with chloroform in a large plastic bag” (Shermer 276).

Indeed, this Cartesian model remained dominant in research labs until the early 1980s. Since then, regulatory oversight has mitigated the worst abuses, though experimentation continues (Pinker 456). The point is that the Cartesian worldview still plays an important, though hidden role, in society today. People benefit from the cheap food factory farms produce and the medical technologies developed from lab testing. Out of sight, out of mind, is a time-tested way to commit atrocities without provoking the moral disgust of the public. All for the greater good...the ends justify the means...and so on, are some defenses you'll hear for these practices.

Going back to Descartes: Vivisecting a live dog only horrifies us because it is a particular example we can imagine. Anyone doing this to a dog today would be condemned as a monster and subject to criminal prosecution. What Descartes did is multiplied millions of times a day , though most shrug since this is happening out-of-site in windowless buildings where it exists as little more than an abstraction.

Suffering tastes good, and even more so when I don't have to see it or smell it or hear it.

Next, I want to show how Kant's ethical compartmentalization creates an uncomfortable psychological tension between the costs versus the benefits of these practices.

The Kantian Model and the Ambivalence of the Modern Consumer

Immanuel Kant seems like more continuity with the past than anything novel. Similar to Aristotle, he stated, “But since animals exist only as means, and not for their own sakes, in that they have no self-consciousness, whereas man is the end, such that I can no longer ask: Why does he exist?, as what can be done with animals, it follows that we have no immediate duties to animals; our duties towards them are indirect duties to humanity ” (Kant, Lectures 212).

Like Descartes, Reason was paramount. Only a rational being can be moral and treat other rational beings as ends rather than means. Irrational beings - which are everything else - were not moral since they could not reason.

They were therefore excluded from ethical consideration (Kant, Ethical Philosophy 35-36).

But like Aquinas, Kant argued that people should avoid animal cruelty lest it leads to sadism, which (of course) would be unethical.

Andreas-Holger Maehle sums up Kant’s position on animals: “ Animals suffering as such was not ethically relevant here, but only the effects of cruelty on human morality” (Manning 92).

That is true but there's more to it. Kant's emphasis on avoiding animal cruelty, whatever the motive, contrasts with Descartes’ utter indifference. There is some room here for common ground with later animal rights advocates. If we get past his exclusion of animals from our moral calculus, there is a limited animal ethic here, representing an advance from the cold Cartesian thinking. It may appear paradoxical, but Kant’s guidance is that we should not mistreat animals, if not for their sake, then for ours.

He cites the example of an old dog who has faithfully served his owner for years. According to Kant, the comparable human behavior on the dog’s part is faithful loyalty. Thus, the owner has the ethical duty of looking after the dog in its old age rather than killing it for being useless.

Kant writes, “So if the acts of animals arise out of the same principium from which human actions spring, and the animal actions are analogs of this, we have duties to animals, in that we thereby promote the cause of humanity. For a person who already displays such cruelty to animals is also no less hardened towards men” (212).

Kant is hinting here that animals actually suffer when mistreated. Only a monster willfully harms helpless creatures. Someone who can inflict pain or death on an animal with cold indifference is a short step away from doing it to people. Though in Kant’s moral universe, people stand above animals because of Reason, their suffering at least merits some limited consideration.

Julian Franklin agrees with this interpretation: “If the infliction of pain and death on animals, without legitimating cause, is not cruel per se, why should it harden us toward humans? And if it does, in fact, harden us toward humans, it must be because we have become insensitive to the wrongful harming of animals” (Franklin 37).

Kantian ambivalence represents a significant tension in the modern consumer. Kant felt that animals exist as a means to our ends and therefore did not deserve ethical consideration. By this reasoning, a justification for unrestricted animal use that is congruent with Cartesian factory farming seems to follow. However, he also said we shouldn't abuse animals. This appears to argue against the status quo.

This contradictory friction between conscience and appetite defines the attitude of most people. It often goes unresolved, as avoidance is made all the easier because what happens at factory farms stays hidden at factory farms. Still, one cannot help but feel that Kant represents a moral improvement over Descartes regarding how we treat animals. Maybe animals are not worthy of equal consideration by Kantian logic, but we still have to treat them well.

But that's easier said than done. The Cartesian system shields the Kantian from too much uncomfortable knowledge. The suffering of cattle, chickens, and pigs is so spatially remote it becomes impossible to conceptualize. The closest the average consumer ever comes to a CAFO or a slaughterhouse is while perusing the grocery store's neatly packaged, bloodless meat section.

Dr. Melanie Joy was spot on when she wrote: “Indeed, it is only because of technology that widespread meat production is possible: modern methods enable us to eat billions of animals every year without witnessing a single part of the process by which these animals become our food” (Joy 124).

Here is the Kantian food model in all its glory: People live two parallel but contradictory ethical lives concerning animals. On the one hand, most truly love their pets and establish deep emotional bonds. The numbers back this up in America, the country with the highest pet population in the world, at just over 140 million dogs and cats. Around 66% of Americans own pets; 85% of dog owners and 76% of cat owners consider their pets as part of the family.

I would wager the percentage of pet owners willing to dine on their furry family members would be around zero. But nary a thought on the chopped-up bits and pieces of other animals that end up on their dinner plates.

“We tolerate this schizophrenia because the life of the pig has moved out of view; when’s the last time you saw a pig in person? Meat comes from the grocery store, where it is cut and packaged to look as little like parts of animals as possible” (Pollan 306).

Pollan calls this modern Kantian ambivalence toward animals the "Omnivore’s Dilemma" because the ethics of what we eat present a constant tension between the nobility of our good intentions and the consequences of our actions. Many otherwise decent and kind people can sometimes have glaring moral blind spots. This is one of them.

Covering the 2003 Maine Lobster Festival for Gourmet Magazine, David Foster Wallace expressed these contradictions when he mused in a now-famous essay called "Consider the Lobster" about the festival’s star attraction. Wallace, an omnivore before and after the article, nevertheless expressed how misgivings often arise when one stops for a moment to challenge underlying assumptions about what some other creature is experiencing.

"How do people who view themselves as morally responsible justify their participation in the current food production system? That is a difficult question for many to answer, or even face. The more important point here, though, is that the whole animal-cruelty-and-eating issue is not just complex, it’s also uncomfortable. It is, at any rate, uncomfortable for me, and for just about everyone I know who enjoys a variety of foods and yet does not want to see herself as cruel or unfeeling. As far as I can tell, my own main way of dealing with this conflict has been to avoid thinking about the whole unpleasant thing. I should add that it appears to me unlikely that many readers of Gourmet wish to think hard about it, either, or to be queried about the morality of their eating habits in the pages of a culinary monthly" (Wallace).

Consider Wallace an uncomfortably aware and conflicted Kantian. In any case, he was right: Many do not wish "to think hard about it...or be queried about the morality of their eating habits." Joy has a theory that people engage in a psychological trick called "de-individuation" that helps them reconcile the contradictions they can't flat-out ignore. “De-individuation is the process of viewing individuals only in terms of their group identity and as having the same characteristics as everyone else in the group” (Joy 119).

De-individuation becomes much easier when our role is limited to consumption remote from the production process. Wallace's essay was a noble attempt to confront mass de-individuation, not directed at a bird or mammal where some sympathy might easier be found, but at the alien and insect-like lobster.

Consider a simple thought experiment to highlight Joy's point: Would we allow our beloved pet to be treated the same way as a factory-farmed hog or even a lobster? Really, what's the difference between the two?

I've asked these questions many times over the years and have never received a satisfactory answer that gets at the heart of the matter. That answer, it seems clear to me, is that one is seen as an individual. The other is not. That's it. We are biologically hardwired to form emotional connections with what we know and experience firsthand while rationalizing unethical behavior for those outside our circle of direct experience (De Waal, Age of Empathy 221).

The modern Kantian consumer tries to sustain an illusion that it all somehow makes sense, coming up with reasons that sound convincing. Like, for example, eating meat (or not) is merely a lifestyle choice, no better or worse than Vegans who choose a plant-based diet. Or, livestock exists as food for us; therefore, it's ok to eat it. Or, you eat what you want and I eat what I want and we all must respect each other's choices because...freedom. These are just a few of the morally vacuous platitudes I've heard a thousand times. They are not even superficially convincing to anyone who puts any thought into it.

And so it goes: Cartesian factory farms thrive in the shadows, propped by blissfully unaware Kantian consumers dining on cheap and tasty cruelty. At some level, the average person knows that factory farming is wrong. But they never have to think about too much or for too long.

That's on purpose.

Still, there are signs this is changing due to the recent surge of a third, more hopeful way: the Darwinian.

The Modern Darwinian Model and the Expansion of the Moral Arc

Charles Darwin revolutionized the way we view ourselves as a species. As we've seen, Western tradition has long held that human nature contains intrinsic differences from the rest of the animal kingdom.

Darwin shattered this myth by showing how interconnected all life is. Humanity, like the chimpanzee, like the dolphin, like the lobster, like everything, is a product of evolution.

E.O. Wilson describes how pervasive the Darwinian view of life has become. It knocked humanity off its high perch, previously right below God and the angels, and demoted us to just another branch on the tree of life.

“The general traits of human nature appear limited and idiosyncratic when placed against the great backdrop of all other living species. Additional evidence suggests that the more stereotyped forms of human behavior are mammalian and even more specifically primate in character, as predicted on the basis of general evolutionary theory” (Wilson 32).

Indeed, Darwin went so far as to speculate that animals shared the same traits as humans, like sympathy, grief, curiosity, excitement, and boredom, to name but a few (Darwin 100, Descent). To understand how radical this is, contrast the following quote by Darwin in the context of what we've seen so far with Descartes (i.e., animals as mechanical automatons) and Kant (animals as means to ends):

“The lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, &c., when playing together, like our own children” (89).

This paradigm-shifting assertion of humanity’s direct relatedness (". ..like our own children ") to all other life on Earth provided the intellectual foundation to re-conceptualize our ethical stance toward other life.

Peter Singer, a contemporary philosopher and a leading thinker in the animal liberation movement, echoes Darwin and expands upon it. At the heart of Singer’s philosophy is that man and beast share an ability to feel pain and suffer. “If a being suffers there can be no moral justification for refusing to take that suffering into consideration” (Singer 8).

If this is true, then beliefs that animals do not experience pain (Descartes) or do not have interests (Kant) begin falling apart. Since the 1970s, when Singer and others like him began pointing this out, the Cartesian and Kantian models have been on the defensive.

Steven Pinker shows how our ethical stance toward animals represents one aspect of a larger “rights revolution” that has taken place over the last two centuries and includes race, sex, and sexual orientation. He credits Peter Singer for the thesis of his book, The Better Angels of Our Nature , which says,“ …human beings were endowed by natural selection with a kernel of empathy toward kin and allies, and have gradually extended it to wider and wider circles of living things, from family and village to clan, tribe, nation, species, and all of sentient life” (Pinker 465).

According to Pinker, beginning with the rise of Singer's (and others) ideas in the 1970s, Western culture has developed less tolerance for animal cruelty. Modern legislation has curbed many abuses in animal testing and, to a much lesser extent, factory farming. Another book by Michael Shermer, The Moral Arc, makes a similar point but uses Darwinian concepts to make his case.

“A moral system based on continuous rather than categorical thinking gives us a biological and evolutionary foundation for the expansion of the moral sphere to include nonhuman animals, based on objective criteria of genetic relatedness, cognitive abilities, emotional capacities, moral development, and especially the capacity to feel pain and suffer” (Shermer 263).

This is not quite an argument for Singer's ethical Veganism. Still, it is not far off because, for the first time, it advocates for more awareness of how our decisions might harm other sentient life. Remember, these views are now coming from mainstream scientists like Pinker and Shermer and not from hippy-dippy radical animal rights activists. The Overton Window has shifted in favor of the Darwinian model over the last forty years.

What was once done thoughtlessly is now remembered with embarrassment. Former lab research assistants like Shermer and Pinker each recount participating in animal experiments with genuine guilt and regret.

Here is how Pinker starts his story about working in an animal lab: “ Let me tell you about the worst thing I have ever done ” (Pinker 454).

Likewise, Shermer recalls his work in a testing lab as “ …one of the most dreadful things I ever had to do ” (Shermer 276). These two examples show how much the ground has shifted in a very short amount of time. Many who participated in the Cartesian model look back on those times with shame and horror.

There are hints a similar shift in thinking is happening in the general population, with more widespread support for legislation protecting animals from the worst abuses in factory farms and laboratories (Shermer 284-288). Alternative options like plant-based milk and meat are carving out larger market shares. There is reason for cautious optimism for the future.

Final thoughts: Animal Ethics and Philosophy

This essay's purpose is not to argue how one of these paradigms will triumph anytime soon. It should be clear at this point, however, that I endorse a more Darwinian-friendly view. However, for most Americans, all three continue to play a role, though sometimes in contradictory ways.

And if specific trends show encouraging signs for the future, others are downright depressing. The Cartesian model supplies modern society with cheap and abundant animal products, though at a substantial moral and environmental cost. In 2022, an estimated 99% of all farm animals reside in factory farms, often in deplorable conditions.

The default response for the vast majority is to morally compartmentalize the mind to wall off the contradictions from each other. That way, people can call themselves animal lovers while consuming meat and dairy daily. It works pretty well when over 90% of the population plays the same game. Who will challenge them? Just picture the average American family sitting down for a steak dinner with the family pets hovering on the margins to notice how intertwined all three models remain.

A growing consciousness of the similarities and continuities between all species, including man, should not downplay the continuing dominance of the Cartesian and Kantian models. The moral dilemmas raised by the Darwinian model, compelling as they are, remain muted in a society where roughly 95% of the population still consumes animal products with unquestioning devotion. As more people worldwide enter the middle classes and have more disposable income, they will undoubtedly aspire to eat a meat-heavy diet like we do in the developed world.

Moreover, dramatic shifts in ethical behavior do not come quickly when one must sacrifice personal pleasures for what appears to be mere abstractions. "What difference will one person like me make by not eating meat? And at what social cost will it be to MY happiness? It seems like so much sacrifice for so little! So then, why do it?" The apparent futility of it all is often enough to smother any motivation to change one's habits.

In this way, even a valid argument against eating meat and dairy is often countered by habit, societal norms, economics, and safety in numbers (herd mentality). This makes changing the status quo daunting, at least for the near future, and should temper any Vegan illusions of an impending plant-based utopia.

The adage that people want to eat sausage, not watch it made, is literally true here and explains how acceptable factory farming remains, at least as long as we don't know too much about it. But you cannot supply endless and affordable animal products for an affluent and urbanized society by treating tens of billions of livestock "humanely." The current paradigm depends on an economy of scale to keep shelves stocked and prices low, and that takes little account of the welfare of the livestock involved.

The producer and consumer thrive in a symbiotic relationship of cheap, abundant food in exchange for the public's 'hear-no-evil-see-no-evil' attitude. However, with a modern interpretation of Darwinian ideas by animal welfare advocates, a growing wedge between the Kantian and Cartesian models is emerging. These advocates are lifting the shroud of ignorance surrounding the methods used to produce our food.

Meatless options are now abundant in grocery stores when before they were not. New products like Beyond Meat and the Impossible Burger have bridged the taste gap between meat and plant-based meat substitutes. Most restaurants now have a solid selection of Vegan and vegetarian options. This was not the case before. These are also positive trends.

As the market shifts along with our consciousness, perhaps factory farming will be a thing of the past someday. It's not enough to know about the evils of the system.

One much choose to do otherwise. Until then, nothing happens but more of the same, and more of the same is an abomination.

Works Cited

Broughton, Janet, John Carriero, and Gary Hatfield. A Companion to Descartes. Malden, MA: Wiley-Blackwell, 2011. Print.

Darwin, Charles. The Descent of Man, and Selection in Relation to Sex. London: Penguin, 2004. Print.

Descartes, René. Meditations and Other Metaphysical Writings. London: Penguin, 1998. Print.

"Farm Animal Statistics: Slaughter Totals : The Humane Society of the United States." RSS. The Human Society of the United States, n.d. Web. 09 Feb. 2015.

Francis, Pope. “ENCYCLICAL LETTER LAUDATO SI’ OF THE HOLY FATHER FRANCIS ON CARE FOR OUR COMMON HOME.” Laudato Si' (24 May 2015) | Francis, 24 May 2015, w2.vatican.va/content/francesco/en/encyclicals/documents/papa-francesco_20150524_enciclica-laudato-si.html#_ftnref69.

Franklin, Julian H. Animal Rights and Moral Philosophy. New York: Columbia UP, 2005. Print.

Joy, Melanie. Why We Love Dogs, Eat Pigs and Wear Cows: An Introduction to Carnism. Berkeley, CA: Conari, 2011. Print.

Kaminer, Ariel. "The Meat You Eat." The New York Times. The New York Times, 05 May 2012. Web. 10 Feb. 2015.

Kant, Immanuel. Ethical Philosophy. Indianapolis, IN: Hackett Pub., 1994. Print.

Kant, Immanuel. Lectures on Ethics. New York: Cambridge UP, 1997. Print.

Manning, Aubrey, James Serpell, and Andreas-Holger Maehle. Animals and Human Society: Changing Perspectives. London: Routledge, 1994. Print.

Pinker, Steven. The Better Angels of Our Nature: The Decline of Violence in History and Its Causes. New York: Penguin, 2011. Print.

Pollan, Michael. The Omnivore's Dilemma: A Natural History of Four Meals. New York: Penguin, 2006. Print.

Rawls, John. A Theory of Justice. Cambridge, MA: Belknap, 2005. Print.

Shermer, Michael. The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom. New York: Henry Holt, 2015. Print.

Singer, Peter. Animal Liberation: The Definitive Classic of the Animal Movement. New York: Harper Perennial, 2009. Print.

Singer, Peter, Jim Mason. The Ethics of What We Eat: Why Our Food Choices Matter. Emmaus, PA: Rodale, 2006. Print.

Tuttle, Will, ed. Circles of Compassion Essays Connecting Issues of Justice. Danvers: Vegan Pub, 2014. Print.

Wallace, David F. "Consider the Lobster." Gourmet.com. Gourmet, 2004. Web. 11 Feb. 2015.

Wilson, Edward O. On Human Nature. Cambridge, MA: Harvard UP, 2004. Print.

#Kant #Darwin #Descartes #ethics #animals #philosophy #morality

First published 6 Jun 2019 - Paris, France

Updates and edits 23 Jul 23 - Falls Church, VA

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• J Prev Med Hyg
• v.63(2 Suppl 3); 2022 Jun

Ethical considerations regarding animal experimentation

Aysha karim kiani.

1 Allama Iqbal Open University, Islamabad, Pakistan

2 MAGI EUREGIO, Bolzano, Italy

DEREK PHEBY

3 Society and Health, Buckinghamshire New University, High Wycombe, UK

GARY HENEHAN

4 School of Food Science and Environmental Health, Technological University of Dublin, Dublin, Ireland

RICHARD BROWN

5 Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada

PAUL SIEVING

6 Department of Ophthalmology, Center for Ocular Regenerative Therapy, School of Medicine, University of California at Davis, Sacramento, CA, USA

PETER SYKORA

7 Department of Philosophy and Applied Philosophy, University of St. Cyril and Methodius, Trnava, Slovakia

ROBERT MARKS

8 Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

BENEDETTO FALSINI

9 Institute of Ophthalmology, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy

NATALE CAPODICASA

10 MAGI BALKANS, Tirana, Albania

STANISLAV MIERTUS

11 Department of Biotechnology, University of SS. Cyril and Methodius, Trnava, Slovakia

12 International Centre for Applied Research and Sustainable Technology, Bratislava, Slovakia

LORENZO LORUSSO

13 UOC Neurology and Stroke Unit, ASST Lecco, Merate, Italy

DANIELE DONDOSSOLA

14 Center for Preclincal Research and General and Liver Transplant Surgery Unit, Fondazione IRCCS Ca‘ Granda Ospedale Maggiore Policlinico, Milan, Italy

15 Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy

GIANLUCA MARTINO TARTAGLIA

16 Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy

17 UOC Maxillo-Facial Surgery and Dentistry, Fondazione IRCCS Ca Granda, Ospedale Maggiore Policlinico, Milan, Italy

MAHMUT CERKEZ ERGOREN

18 Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus

MUNIS DUNDAR

19 Department of Medical Genetics, Erciyes University Medical Faculty, Kayseri, Turkey

SANDRO MICHELINI

20 Vascular Diagnostics and Rehabilitation Service, Marino Hospital, ASL Roma 6, Marino, Italy

DANIELE MALACARNE

21 MAGI’S LAB, Rovereto (TN), Italy

GABRIELE BONETTI

Astrit dautaj, kevin donato, maria chiara medori, tommaso beccari.

22 Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy

MICHELE SAMAJA

23 MAGI GROUP, San Felice del Benaco (BS), Italy

STEPHEN THADDEUS CONNELLY

24 San Francisco Veterans Affairs Health Care System, University of California, San Francisco, CA, USA

DONALD MARTIN

25 Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC-IMAG, SyNaBi, Grenoble, France

ASSUNTA MORRESI

26 Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy

ARIOLA BACU

27 Department of Biotechnology, University of Tirana, Tirana, Albania

KAREN L. HERBST

28 Total Lipedema Care, Beverly Hills California and Tucson Arizona, USA

MYKHAYLO KAPUSTIN

29 Federation of the Jewish Communities of Slovakia

LIBORIO STUPPIA

30 Department of Psychological, Health and Territorial Sciences, School of Medicine and Health Sciences, University "G. d'Annunzio", Chieti, Italy

LUDOVICA LUMER

31 Department of Anatomy and Developmental Biology, University College London, London, UK

GIAMPIETRO FARRONATO

Matteo bertelli.

32 MAGISNAT, Peachtree Corners (GA), USA

Animal experimentation is widely used around the world for the identification of the root causes of various diseases in humans and animals and for exploring treatment options. Among the several animal species, rats, mice and purpose-bred birds comprise almost 90% of the animals that are used for research purpose. However, growing awareness of the sentience of animals and their experience of pain and suffering has led to strong opposition to animal research among many scientists and the general public. In addition, the usefulness of extrapolating animal data to humans has been questioned. This has led to Ethical Committees’ adoption of the ‘four Rs’ principles (Reduction, Refinement, Replacement and Responsibility) as a guide when making decisions regarding animal experimentation. Some of the essential considerations for humane animal experimentation are presented in this review along with the requirement for investigator training. Due to the ethical issues surrounding the use of animals in experimentation, their use is declining in those research areas where alternative in vitro or in silico methods are available. However, so far it has not been possible to dispense with experimental animals completely and further research is needed to provide a road map to robust alternatives before their use can be fully discontinued.

How to cite this article: Kiani AK, Pheby D, Henehan G, Brown R, Sieving P, Sykora P, Marks R, Falsini B, Capodicasa N, Miertus S, Lorusso L, Dondossola D, Tartaglia GM, Ergoren MC, Dundar M, Michelini S, Malacarne D, Bonetti G, Dautaj A, Donato K, Medori MC, Beccari T, Samaja M, Connelly ST, Martin D, Morresi A, Bacu A, Herbst KL, Kapustin M, Stuppia L, Lumer L, Farronato G, Bertelli M. Ethical considerations regarding animal experimentation. J Prev Med Hyg 2022;63(suppl.3):E255-E266. https://doi.org/10.15167/2421-4248/jpmh2022.63.2S3.2768

Introduction

Animal model-based research has been performed for a very long time. Ever since the 5 th century B.C., reports of experiments involving animals have been documented, but an increase in the frequency of their utilization has been observed since the 19 th century [ 1 ]. Most institutions for medical research around the world use non-human animals as experimental subjects [ 2 ]. Such animals might be used for research experimentations to gain a better understanding of human diseases or for exploring potential treatment options [ 2 ]. Even those animals that are evolutionarily quite distant from humans, such as Drosophila melanogaster , Zebrafish ( Danio rerio ) and Caenorhabditis elegans , share physiological and genetic similarities with human beings [ 2 ]; therefore animal experimentation can be of great help for the advancement of medical science [ 2 ].

For animal experimentation, the major assumption is that the animal research will be of benefit to humans. There are many reasons that highlight the significance of animal use in biomedical research. One of the major reasons is that animals and humans share the same biological processes. In addition, vertebrates have many anatomical similarities (all vertebrates have lungs, a heart, kidneys, liver and other organs) [ 3 ]. Therefore, these similarities make certain animals more suitable for experiments and for providing basic training to young researchers and students in different fields of biological and biomedical sciences [ 3 ]. Certain animals are susceptible to various health problems that are similar to human diseases such as diabetes, cancer and heart disease [ 4 ]. Furthermore, there are genetically modified animals that are used to obtain pathological phenotypes [ 5 ]. A significant benefit of animal experimentation is that test species can be chosen that have a much shorter life cycle than humans. Therefore, animal models can be studied throughout their life span and for several successive generations, an essential element for the understanding of disease progression along with its interaction with the whole organism throughout its lifetime [ 6 ].

Animal models often play a critical role in helping researchers who are exploring the efficacy and safety of potential medical treatments and drugs. They help to identify any dangerous or undesired side effects, such as birth defects, infertility, toxicity, liver damage or any potential carcinogenic effects [ 7 ]. Currently, U.S. Federal law, for example, requires that non-human animal research is used to demonstrate the efficacy and safety of any new treatment options before proceeding to trials on humans [ 8 ]. Of course, it is not only humans benefit from this research and testing, since many of the drugs and treatments that are developed for humans are routinely used in veterinary clinics, which help animals live longer and healthier lives [ 4 ].

COVID-19 AND THE NEED FOR ANIMAL MODELS

When COVID-19 struck, there was a desperate need for research on the disease, its effects on the brain and body and on the development of new treatments for patients with the disease. Early in the disease it was noticed that those with the disease suffered a loss of smell and taste, as well as neurological and psychiatric symptoms, some of which lasted long after the patients had “survived” the disease [ 9-15 ]. As soon as the pandemic started, there was a search for appropriate animal models in which to study this unknown disease [ 16 , 17 ]. While genetically modified mice and rats are the basic animal models for neurological and immunological research [ 18 , 19 ] the need to understand COVID-19 led to a range of animal models; from fruit flies [ 20 ] and Zebrafish [ 21 ] to large mammals [ 22 , 23 ] and primates [ 24 , 25 ]. And it was just not one animal model that was needed, but many, because different aspects of the disease are best studied in different animal models [ 16 , 25 , 26 ]. There is also a need to study the transmission pathways of the zoonosis: where does it come from, what are the animal hosts and how is it transferred to humans [ 27 ]?

There has been a need for animal models for understanding the pathophysiology of COVID-19 [ 28 ], for studying the mechanisms of transmission of the disease [ 16 ], for studying its neurobiology [ 29 , 30 ] and for developing new vaccines [ 31 ]. The sudden onset of the COVID-19 pandemic has highlighted the fact that animal research is necessary, and that the curtailment of such research has serious consequences for the health of both humans and animals, both wild and domestic [ 32 ] As highlighted by Adhikary et al. [ 22 ] and Genzel et al. [ 33 ] the coronavirus has made clear the necessity for animal research and the danger in surviving future such pandemics if animal research is not fully supported. Genzel et al. [ 33 ], in particular, take issue with the proposal for a European ban on animal testing. Finally, there is a danger in bypassing animal research in developing new vaccines for diseases such as COVID-19 [ 34 ]. The purpose of this paper is to show that, while animal research is necessary for the health of both humans and animals, there is a need to carry out such experimentation in a controlled and humane manner. The use of alternatives to animal research such as cultured human cells and computer modeling may be a useful adjunct to animal studies but will require that such methods are more readily accessible to researchers and are not a replacement for animal experimentation.

Pros and cons of animal experimentation

Arguments against animal experimentation.

A fundamental question surrounding this debate is to ask whether it is appropriate to use animals for medical research. Is our acceptance that animals have a morally lower value or standard of life just a case of speciesism [ 35 ]? Nowadays, most people agree that animals have a moral status and that needlessly hurting or abusing pets or other animals is unacceptable. This represents something of a change from the historical point of view where animals did not have any moral status and the treatment of animals was mostly subservient to maintaining the health and dignity of humans [ 36 ].

Animal rights advocates strongly argue that the moral status of non-human animals is similar to that of humans, and that animals are entitled to equality of treatment. In this view, animals should be treated with the same level of respect as humans, and no one should have the right to force them into any service or to kill them or use them for their own goals. One aspect of this argument claims that moral status depends upon the capacity to suffer or enjoy life [ 37 ].

In terms of suffering and the capacity of enjoying life, many animals are not very different from human beings, as they can feel pain and experience pleasure [ 38 ]. Hence, they should be given the same moral status as humans and deserve equivalent treatment. Supporters of this argument point out that according animals a lower moral status than humans is a type of prejudice known as “speciesism” [ 38 ]. Among humans, it is widely accepted that being a part of a specific race or of a specific gender does not provide the right to ascribe a lower moral status to the outsiders. Many advocates of animal rights deploy the same argument, that being human does not give us sufficient grounds declare animals as being morally less significant [ 36 ].

ARGUMENTS IN FAVOR OF ANIMAL EXPERIMENTATION

Those who support animal experimentation have frequently made the argument that animals cannot be elevated to be seen as morally equal to humans [ 39 ]. Their main argument is that the use of the terms “moral status” or “morality” is debatable. They emphasize that we must not make the error of defining a quality or capacity associated with an animal by using the same adjectives used for humans [ 39 ]. Since, for the most part, animals do not possess humans’ cognitive capabilities and lack full autonomy (animals do not appear to rationally pursue specific goals in life), it is argued that therefore, they cannot be included in the moral community [ 39 ]. It follows from this line of argument that, if animals do not possess the same rights as human beings, their use in research experimentation can be considered appropriate [ 40 ]. The European and the American legislation support this kind of approach as much as their welfare is respected.

Another aspect of this argument is that the benefits to human beings of animal experimentation compensate for the harm caused to animals by these experiments.

In other words, animal harm is morally insignificant compared to the potential benefits to humans. Essentially, supporters of animal experimentation claim that human beings have a higher moral status than animals and that animals lack certain fundamental rights accorded to humans. The potential violations of animal rights during animal research are, in this way, justified by the greater benefits to mankind [ 40 , 41 ]. A way to evaluate when the experiments are morally justified was published in 1986 by Bateson, which developed the Bateson’s Cube [ 42 ]. The Cube has three axes: suffering, certainty of benefit and quality of research. If the research is high-quality, beneficial, and not inflicting suffering, it will be acceptable. At the contrary, painful, low-quality research with lower likelihood of success will not be acceptable [ 42 , 43 ].

Impact of experimentations on animals

Ability to feel pain and distress.

Like humans, animal have certain physical as well as psychological characteristics that make their use for experimentation controversial [ 44 ].

In the last few decades, many studies have increased knowledge of animal awareness and sentience: they indicate that animals have greater potential to experience damage than previously appreciated and that current rights and protections need to be reconsidered [ 45 ]. In recent times, scientists as well as ethicists have broadly acknowledged that animals can also experience distress and pain [ 46 ]. Potential sources of such harm arising from their use in research include disease, basic physiological needs deprivation and invasive procedures [ 46 ]. Moreover, social deprivation and lack of the ability to carry out their natural behaviors are other causes of animal harm [ 46 ]. Several studies have shown that, even in response to very gentle handling and management, animals can show marked alterations in their physiological and hormonal stress markers [ 47 ].

In spite of the fact that suffering and pain are personalized experiences, several multi-disciplinary studies have provided clear evidence of animals experiencing pain and distress. In particular, some animal species have the ability to express pain similarly to human due to common psychological, neuroanatomical and genetic characteristics [ 48 ]. Similarly, animals share a resemblance to humans in their developmental, genetic and environmental risk factors for psychopathology. For instance, in many species, it has been shown that fear operates within a less organized subcortical neural circuit than pain [ 49 , 50 ]. Various types of depression and anxiety disorders like posttraumatic stress disorder have also been reported in mammals [ 51 ].

PSYCHOLOGICAL CAPABILITIES OF ANIMALS

Some researchers have suggested that besides their ability to experience physical and psychological pain and distress, some animals also exhibit empathy, self-awareness and language-like capabilities. They also demonstrate tools-linked cognizance, pleasure-seeking and advanced problem-solving skills [ 52 ]. Moreover, mammals and birds exhibit playful behavior, an indicator of the capacity to experience pleasure. Other taxa such as reptiles, cephalopods and fishes have also been observed to display playful behavior, therefore the current legislation prescribes the use of environmental enrichers [ 53 ]. The presence of self-awareness ability, as assessed by mirror self-recognition, has been reported in magpies, chimpanzees and other apes, and certain cetaceans [ 54 ]. Recently, another study has revealed that crows have the ability to create and use tools that involve episodic-like memory formation and its retrieval. From these findings, it may be suggested that crows as well as related species show evidence of flexible learning strategies, causal reasoning, prospection and imagination that are similar to behavior observed in great apes [ 55 ]. In the context of resolving the ethical dilemmas about animal experimentation, these observations serve to highlight the challenges involved [ 56 , 57 ].

Ethics, principles and legislation in animal experimentation

Ethics in animal experimentation.

Legislation around animal research is based on the idea of the moral acceptability of the proposed experiments under specific conditions [ 58 ]. The significance of research ethics that ensures proper treatment of experimental animals [ 58 ]. To avoid undue suffering of animals, it is important to follow ethical considerations during animal studies [ 1 ]. It is important to provide best human care to these animals from the ethical and scientific point of view [ 1 ]. Poor animal care can lead to experimental outcomes [ 1 ]. Thus, if experimental animals mistreated, the scientific knowledge and conclusions obtained from experiments may be compromised and may be difficult to replicate, a hallmark of scientific research [ 1 ]. At present, most ethical guidelines work on the assumption that animal experimentation is justified because of the significant potential benefits to human beings. These guidelines are often permissive of animal experimentation regardless of the damage to the animal as long as human benefits are achieved [ 59 ].

PRINCIPLE OF THE 4 RS

Although animal experimentation has resulted in many discoveries and helped in the understanding numerous aspects of biological science, its use in various sectors is strictly controlled. In practice, the proposed set of animal experiments is usually considered by a multidisciplinary Ethics Committee before work can commence [ 60 ]. This committee will review the research protocol and make a judgment as to its sustainability. National and international laws govern the utilization of animal experimentation during research and these laws are mostly based on the universal doctrine presented by Russell and Burch (1959) known as principle of the 3 Rs. The 3Rs referred to are Reduction, Refinement and Replacement, and are applied to protocols surrounding the use of animals in research. Some researchers have proposed another “R”, of responsibility for the experimental animal as well as for the social and scientific status of the animal experiments [ 61 ]. Thus, animal ethics committees commonly review research projects with reference to the 4 Rs principles [ 62 ].

The first “R”, Reduction means that the experimental design is examined to ensure that researchers have reduced the number of experimental animals in a research project to the minimum required for reliable data [ 59 ]. Methods used for this purpose include improved experimental design, extensive literature search to avoid duplication of experiments [ 35 ], use of advanced imaging techniques, sharing resources and data, and appropriate statistical data analysis that reduce the number of animals needed for statistically significant results [ 2 , 63 ].

The second “R”, Refinement involves improvements in procedure that minimize the harmful effects of the proposed experiments on the animals involved, such as reducing pain, distress and suffering in a manner that leads to a general improvement in animal welfare. This might include for example improved living conditions for research animals, proper training of people handling animals, application of anesthesia and analgesia when required and the need for euthanasia of the animals at the end of the experiment to curtail their suffering [ 63 ].

The third “R”, Replacement refers to approaches that replace or avoid the use of experimental animals altogether. These approaches involve use of in silico methods/computerized techniques/software and in vitro methods like cell and tissue culture testing, as well as relative replacement methods by use of invertebrates like nematode worms, fruit flies and microorganisms in place of vertebrates and higher animals [ 1 ]. Examples of proper application of these first “3R2 principles are the use of alternative sources of blood, the exploitation of commercially used animals for scientific research, a proper training without use of animals and the use of specimen from previous experiments for further researches [ 64-67 ].

The fourth “R”, Responsibility refers to concerns around promoting animal welfare by improvements in experimental animals’ social life, development of advanced scientific methods for objectively determining sentience, consciousness, experience of pain and intelligence in the animal kingdom, as well as effective involvement in the professionalization of the public discussion on animal ethics [ 68 ].

OTHER ASPECTS OF ANIMAL RESEARCH ETHICS

Other research ethics considerations include having a clear rationale and reasoning for the use of animals in a research project. Researchers must have reasonable expectation of generating useful data from the proposed experiment. Moreover, the research study should be designed in such a way that it should involve the lowest possible sample size of experimental animals while producing statistically significant results [ 35 ].

All individual researchers that handle experimental animals should be properly trained for handling the particular species involved in the research study. The animal’s pain, suffering and discomfort should be minimized [ 69 ]. Animals should be given proper anesthesia when required and surgical procedures should not be repeated on same animal whenever possible [ 69 ]. The procedure of humane handling and care of experimental animals should be explicitly detailed in the research study protocol. Moreover, whenever required, aseptic techniques should be properly followed [ 70 ]. During the research, anesthetization and surgical procedures on experimental animals should only be performed by professionally skilled individuals [ 69 ].

The Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines that are issued by the National Center for the Replacement, Refinement, and Reduction of Animals in Research (NC3Rs) are designed to improve the documentation surrounding research involving experimental animals [ 70 ]. The checklist provided includes the information required in the various sections of the manuscript i.e. study design, ethical statements, experimental procedures, experimental animals and their housing and husbandry, and more [ 70 ].

It is critical to follow the highest ethical standards while performing animal experiments. Indeed, most of the journals refuse to publish any research data that lack proper ethical considerations [ 35 ].

INVESTIGATORS’ ETHICS

Since animals have sensitivity level similar to the human beings in terms of pain, anguish, survival instinct and memory, it is the responsibility of the investigator to closely monitor the animals that are used and identify any sign of distress [ 71 ]. No justification can rationalize the absence of anesthesia or analgesia in animals that undergo invasive surgery during the research [ 72 ]. Investigators are also responsible for giving high-quality care to the experimental animals, including the supply of a nutritious diet, easy water access, prevention of and relief from any pain, disease and injury, and appropriate housing facilities for the animal species [ 73 ]. A research experiment is not permitted if the damage caused to the animal exceeds the value of knowledge gained by that experiment. No scientific advancement based on the destruction and sufferings of another living being could be justified. Besides ensuring the welfare of animals involved, investigators must also follow the applicable legislation [ 74 , 75 ].

To promote the comfort of experimental animals in England, an animal protection society named: ‘The Society for the Preservation of Cruelty to Animals’ (now the Royal Society for the Prevention of Cruelty to Animals) was established (1824) that aims to prevent cruelty to animal [ 76 ].

ANIMAL WELFARE LAWS

Legislation for animal protection during research has long been established. In 1876 the British Parliament sanctioned the ‘Cruelty to Animals Act’ for animal protection. Russell and Burch (1959) presented the ‘3 Rs’ principles: Replacement, Reduction and Refinement, for use of animals during research [ 61 ]. Almost seven years later, the U.S.A also adopted regulations for the protection of experimental animals by enacting the Laboratory Animal Welfare Act of 1966 [ 60 ]. In Brazil, the Arouca Law (Law No. 11,794/08) regulates the animal use in scientific research experiments [ 76 ].

These laws define the breeding conditions, and regulate the use of animals for scientific research and teaching purposes. Such legal provisions control the use of anesthesia, analgesia or sedation in experiments that could cause distress or pain to experimental animals [ 59 , 76 ]. These laws also stress the need for euthanasia when an experiment is finished, or even during the experiment if there is any intense suffering for the experimental animal [ 76 ].

Several national and international organizations have been established to develop alternative techniques so that animal experimentation can be avoided, such as the UK-based National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) ( www.caat.jhsph.edu ), the European Centre for the Validation of Alternative Methods (ECVAM) [ 77 ], the Universities Federation for Animal Welfare (UFAW) ( www.ufaw.org.uk ), The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) [ 78 ], and The Center for Alternatives to Animal Testing (CAAT) ( www.caat.jhsph.edu ). The Brazilian ‘Arouca Law’ also constitutes a milestone, as it has created the ‘National Council for the Control of Animal Experimentation’ (CONCEA) that deals with the legal and ethical issues related to the use of experimental animals during scientific research [ 76 ].

Although national as well as international laws and guidelines have provided basic protections for experimental animals, the current regulations have some significant discrepancies. In the U.S., the Animal Welfare Act excludes rats, mice and purpose-bred birds, even though these species comprise almost 90% of the animals that are used for research purpose [ 79 ]. On the other hand, certain cats and dogs are getting special attention along with extra protection. While the U.S. Animal Welfare Act ignores birds, mice and rats, the U.S. guidelines that control research performed using federal funding ensure protections for all vertebrates [ 79 , 80 ].

Living conditions of animals

Choice of the animal model.

Based on all the above laws and regulations and in line with the deliberations of ethical committees, every researcher must follow certain rules when dealing with animal models.

Before starting any experimental work, thorough research should be carried out during the study design phase so that the unnecessary use of experimental animals is avoided. Nevertheless, certain research studies may have compelling reasons for the use of animal models, such as the investigation of human diseases and toxicity tests. Moreover, animals are also widely used in the training of health professionals as well as in training doctors in surgical skills [ 1 , 81 ].

Researcher should be well aware of the specific traits of the animal species they intend to use in the experiment, such as its developmental stages, physiology, nutritional needs, reproductive characteristics and specific behaviors. Animal models should be selected on the basis of the study design and the biological relevance of the animal [ 1 ].

Typically, in early research, non-mammalian models are used to get rapid insights into research problems such as the identification of gene function or the recognition of novel therapeutic options. Thus, in biomedical and biological research, among the most commonly used model organisms are the Zebrafish, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans . The main advantage of these non-mammalian animal models is their prolific reproducibility along with their much shorter generation time. They can be easily grown in any laboratory setting, are less expensive than the murine animal models and are somewhat more powerful than the tissue and cell culture approaches [ 82 ].

Caenorhabditis elegans is a small-sized nematode with a short life cycle and that exists in large populations and is relatively inexpensive to cultivate. Scientists have gathered extensive knowledge of the genomics and genetics of Caenorhabditis elegans ; but Caenorhabditis elegans models, while very useful in some respects, are unable to represent all signaling pathways found in humans. Furthermore, due to its short life cycle, scientists are unable to investigate long term effects of test compounds or to analyze primary versus secondary effects [ 6 ].

Similarly, the fruit fly Drosophila melanogaster has played a key role in numerous biomedical discoveries. It is small in size, has a short life cycle and large population size, is relatively inexpensive to breed, and extensive genomics and genetics information is available [ 6 ]. However, its respiratory, cardiovascular and nervous systems differ considerably from human beings. In addition, its immune system is less developed when compared to vertebrates, which is why effectiveness of a drug in Drosophila melanogaster may not be easily extrapolated to humans [ 83 ].

The Zebrafish ( Danio rerio ) is a small freshwater teleost, with transparent embryos, providing easy access for the observation of organogenesis and its manipulation. Therefore, Zebrafish embryos are considered good animal models for different human diseases like tuberculosis and fetal alcohol syndrome and are useful as neurodevelopmental research models. However, Zebrafish has very few mutant strains available, and its genome has numerous duplicate genes making it impossible to create knockout strains, since disrupting one copy of the gene will not disrupt the second copy of that gene. This feature limits the use of Zebrafish as animal models to study human diseases. Additionally they are rather expensive, have long life cycle, and genomics and genetics studies are still in progress [ 82 , 84 ].

Thus, experimentation on these three animals might not be equivalent to experimentation on mammals. Mammalian animal model are most similar to human beings, so targeted gene replacement is possible. Traditionally, mammals like monkey and mice have been the preferred animal models for biomedical research because of their evolutionary closeness to humans. Rodents, particularly mice and rats, are the most frequently used animal models for scientific research. Rats are the most suitable animal model for the study of obesity, shock, peritonitis, sepsis, cancer, intestinal operations, spleen, gastric ulcers, mononuclear phagocytic system, organ transplantations and wound healing. Mice are more suitable for studying burns, megacolon, shock, cancer, obesity, and sepsis as mentioned previously [ 85 ].

Similarly, pigs are mostly used for stomach, liver and transplantation studies, while rabbits are suitable for the study of immunology, inflammation, vascular biology, shock, colitis and transplantations. Thus, the choice of experimental animal mainly depends upon the field of scientific research under consideration [ 1 ].

HOUSING AND ENVIRONMENTAL ENRICHMENT

Researchers should be aware of the environment and conditions in which laboratory animals are kept during research, and they also need to be familiar with the metabolism of the animals kept in vivarium, since their metabolism can easily be altered by different factors such as pain, stress, confinement, lack of sunlight, etc. Housing conditions alter animal behavior, and this can in turn affect experimental results. By contrast, handling procedures that feature environmental enrichment and enhancement help to decrease stress and positively affect the welfare of the animals and the reliability of research data [ 74 , 75 ].

In animals, distress- and agony-causing factors should be controlled or eliminated to overcome any interference with data collection as well as with interpretation of the results, since impaired animal welfare leads to more animal usage during experiment, decreased reliability and increased discrepancies in results along with the unnecessary consumption of animal lives [ 86 ].

To reduce the variation or discrepancies in experimental data caused by various environmental factors, experimental animals must be kept in an appropriate and safe place. In addition, it is necessary to keep all variables like humidity, airflow and temperature at levels suitable for those species, as any abrupt variation in these factors could cause stress, reduced resistance and increased susceptibility to infections [ 74 ].

The space allotted to experimental animals should permit them free movement, proper sleep and where feasible allow for interaction with other animals of the same species. Mice and rats are quite sociable animals and must, therefore, be housed in groups for the expression of their normal behavior. Usually, laboratory cages are not appropriate for the behavioral needs of the animals. Therefore, environmental enrichment is an important feature for the expression of their natural behavior that will subsequently affect their defense mechanisms and physiology [ 87 ].

The features of environmental enrichment must satisfy the animals’ sense of curiosity, offer them fun activities, and also permit them to fulfill their behavioral and physiological needs. These needs include exploring, hiding, building nests and gnawing. For this purpose, different things can be used in their environment, such as PVC tubes, cardboard, igloos, paper towel, cotton, disposable masks and paper strips [ 87 ].

The environment used for housing of animals must be continuously controlled by appropriate disinfection, hygiene protocols, sterilization and sanitation processes. These steps lead to a reduction in the occurrence of various infectious agents that often found in vivarium, such as Sendai virus, cestoda and Mycoplasma pulmonis [ 88 ].

Euthanasia is a term derived from Greek, and it means a death without any suffering. According to the Brazilian Arouca Law (Article 14, Chapter IV, Paragraphs 1 and 2), an animal should undergo euthanasia, in strict compliance with the requirements of each species, when the experiment ends or during any phase of the experiment, wherever this procedure is recommended and/or whenever serious suffering occurs. If the animal does not undergo euthanasia after the intervention it may leave the vivarium and be assigned to suitable people or to the animal protection bodies, duly legalized [ 1 ].

Euthanasia procedures must result in instant loss of consciousness which leads to respiratory or cardiac arrest as well as to complete brain function impairment. Another important aspect of this procedure is calm handling of the animal while taking it out of its enclosure, to reduce its distress, suffering, anxiety and fear. In every research project, the study design should include the details of the appropriate endpoints of these experimental animals, and also the methods that will be adopted. It is important to determine the appropriate method of euthanasia for the animal being used. Another important point is that, after completing the euthanasia procedure, the animal’s death should be absolutely confirmed before discarding their bodies [ 87 , 89 ].

Relevance of animal experimentations and possible alternatives

Relevance of animal experiments and their adverse effects on human health.

One important concern is whether human diseases, when inflicted on experimental animals, adequately mimic the progressions of the disease and the treatment responses observed in humans. Several research articles have made comparisons between human and animal data, and indicated that the results of animals’ research could not always be reliably replicated in clinical research among humans. The latest systematic reviews about the treatment of different clinical conditions including neurology, vascular diseases and others, have established that the results of animal studies cannot properly predict human outcomes [ 59 , 90 ].

At present, the reliability of animal experiments for extrapolation to human health is questionable. Harmful effects may occur in humans because of misleading results from research conducted on animals. For instance, during the late fifties, a sedative drug, thalidomide, was prescribed for pregnant women, but some of the women using that drug gave birth to babies lacking limbs or with foreshortened limbs, a condition called phocomelia. When thalidomide had been tested on almost all animal models such as rats, mice, rabbits, dogs, cats, hamsters, armadillos, ferrets, swine, guinea pig, etc., this teratogenic effect was observed only occasionally [ 91 ]. Similarly, in 2006, the compound TGN 1412 was designed as an immunomodulatory drug, but when it was injected into six human volunteer, serious adverse reactions were observed resulting from a deadly cytokine storm that in turn led to disastrous systemic organ failure. TGN 1412 had been tested successfully in rats, mice, rabbits, and non-human primates [ 92 ]. Moreover, Bailey (2008) reported 90 HIV vaccines that had successful trial results in animals but which failed in human beings [ 93 ]. Moreover, in Parkinson disease, many therapeutic options that have shown promising results in rats and non-human primate models have proved harmful in humans. Hence, to analyze the relevance of animal research to human health, the efficacy of animal experimentation should be examined systematically [ 94 , 95 ]. At the same time, the development of hyperoxaluria and renal failure (up to dialysis) after ileal-jejunal bypass was unexpected because this procedure was not preliminarily evaluated on an animal model [ 96 ].

Several factors play a role in the extrapolation of animal-derived data to humans, such as environmental conditions and physiological parameters related to stress, age of the experimental animals, etc. These factors could switch on or off genes in the animal models that are specific to species and/or strains. All these observations challenge the reliability and suitability of animal experimentation as well as its objectives with respect to human health [ 76 , 92 ].

ALTERNATIVE TO ANIMAL EXPERIMENTATION/DEVELOPMENT OF NEW PRODUCTS AND TECHNIQUES TO AVOID ANIMAL SACRIFICE IN RESEARCH

Certainly, in vivo animal experimentation has significantly contributed to the development of biological and biomedical research. However it has the limitations of strict ethical issues and high production cost. Some scientists consider animal testing an ineffective and immoral practice and therefore prefer alternative techniques to be used instead of animal experimentation. These alternative methods involve in vitro experiments and ex vivo models like cell and tissue cultures, use of plants and vegetables, non-invasive human clinical studies, use of corpses for studies, use of microorganisms or other simpler organism like shrimps and water flea larvae, physicochemical techniques, educational software, computer simulations, mathematical models and nanotechnology [ 97 ]. These methods and techniques are cost-effective and could efficiently replace animal models. They could therefore, contribute to animal welfare and to the development of new therapies that can identify the therapeutics and related complications at an early stage [ 1 ].

The National Research Council (UK) suggested a shift from the animal models toward computational models, as well as high-content and high-throughput in vitro methods. Their reports highlighted that these alternative methods could produce predictive data more affordably, accurately and quickly than the traditional in vivo or experimental animal methods [ 98 ].

Increasingly, scientists and the review boards have to assess whether addressing a research question using the applied techniques of advanced genetics, molecular, computational and cell biology, and biochemistry could be used to replace animal experiments [ 59 ]. It must be remembered that each alternative method must be first validated and then registered in dedicated databases.

An additional relevant concern is how precisely animal data can mirror relevant epigenetic changes and human genetic variability. Langley and his colleagues have highlighted some of the examples of existing and some emerging non-animal based research methods in the advanced fields of neurology, orthodontics, infectious diseases, immunology, endocrine, pulmonology, obstetrics, metabolism and cardiology [ 99 ].

IN SILICO SIMULATIONS AND INFORMATICS

Several computer models have been built to study cardiovascular risk and atherosclerotic plaque build-up, to model human metabolism, to evaluate drug toxicity and to address other questions that were previously approached by testing in animals [ 100 ].

Computer simulations can potentially decrease the number of experiments required for a research project, however simulations cannot completely replace laboratory experiments. Unfortunately, not all the principles regulating biological systems are known, and computer simulation provide only an estimation of possible effects due to the limitations of computer models in comparison with complex human tissues. However, simulation and bio-informatics are now considered essential in all fields of science for their efficiency in using the existing knowledge for further experimental designs [ 76 ].

At present, biological macromolecules are regularly simulated at various levels of detail, to predict their response and behavior under certain physical conditions, chemical exposures and stimulations. Computational and bioinformatic simulations have significantly reduced the number of animals sacrificed during drug discovery by short listing potential candidate molecules for a drug. Likewise, computer simulations have decreased the number of animal experiments required in other areas of biological science by efficiently using the existing knowledge. Moreover, the development of high definition 3D computer models for anatomy with enhanced level of detail, it may make it possible to reduce or eliminate the need for animal dissection during teaching [ 101 , 102 ].

3D CELL-CULTURE MODELS AND ORGANS-ON-CHIPS

In the current scenario of rapid advancement in the life sciences, certain tissue models can be built using 3D cell culture technology. Indeed, there are some organs on micro-scale chip models used for mimicking the human body environment. 3D models of multiple organ systems such as heart, liver, skin, muscle, testis, brain, gut, bone marrow, lungs and kidney, in addition to individual organs, have been created in microfluidic channels, re-creating the physiological chemical and physical microenvironments of the body [ 103 ]. These emerging techniques, such as the biomedical/biological microelectromechanical system (Bio-MEMS) or lab-on-a-chip (LOC) and micro total analysis systems (lTAS) will, in the future, be a useful substitute for animal experimentation in commercial laboratories in the biotechnology, environmental safety, chemistry and pharmaceutical industries. For 3D cell culture modeling, cells are grown in 3D spheroids or aggregates with the help of a scaffold or matrix, or sometimes using a scaffold-free method. The 3D cell culture modeling conditions can be altered to add proteins and other factors that are found in a tumor microenvironment, for example, or in particular tissues. These matrices contain extracellular matrix components such as proteins, glycoconjugates and glycosaminoglycans that allow for cell communication, cell to cell contact and the activation of signaling pathways in such a way that the morphological and functional differentiation of these cells can accurately mimic their environment in vivo . This methodology, in time, will bridge the gap between in vivo and in vitro drug screening, decreasing the utilization of animal models during research [ 104 ].

ALTERNATIVES TO MICROBIAL CULTURE MEDIA AND SERUM-FREE ANIMAL CELL CULTURES

There are moves to reduce the use of animal derived products in many areas of biotechnology. Microbial culture media peptones are mostly made by the proteolysis of farmed animal meat. However, nowadays, various suppliers provide peptones extracted from yeast and plants. Although the costs of these plant-extracted peptones are the same as those of animal peptones, plant peptones are more environmentally favorable since less plant material and water are required for them to grow, compared with the food grain and fodder needed for cattle that are slaughtered for animal peptone production [ 105 ].

Human cell culture is often carried out in a medium that contains fetal calf serum, the production of which involves animal (cow) sacrifice or suffering. In fact, living pregnant cows are used and their fetuses removed to harvest the serum from the fetal blood. Fetal calf serum is used because it is a natural medium rich in all the required nutrients and significantly increases the chances of successful cell growth in culture. Scientists are striving to identify the factors and nutrients required for the growth of various types of cells, with a view to eliminating the use of calf serum. At present, most cell lines could be cultured in a chemically-synthesized medium without using animal products. Furthermore, data from chemically-synthesized media experiments may have better reproducibility than those using animal serum media, since the composition of animal serum does change from batch to batch on the basis of animals’ gender, age, health and genetic background [ 76 ].

ALTERNATIVES TO ANIMAL-DERIVED ANTIBODIES

Animal friendly affinity reagents may act as an alternative to antibodies produced, thereby removing the need for animal immunization. Typically, these antibodies are obtained in vitro by yeast, phage or ribosome display. In a recent review, a comparative analysis between animal friendly affinity reagents and animal derived-antibodies showed that the affinity reagents have superior quality, are relatively less time consuming, have more reproducibility and are more reliable and are cost-effective [ 106 , 107 ].

Conclusions

Animal experimentation led to great advancement in biological and biomedical sciences and contributed to the discovery of many drugs and treatment options. However, such experimentation may cause harm, pain and distress to the animals involved. Therefore, to perform animal experimentations, certain ethical rules and laws must be strictly followed and there should be proper justification for using animals in research projects. Furthermore, during animal experimentation the 4 Rs principles of reduction, refinement, replacement and responsibility must be followed by the researchers. Moreover, before beginning a research project, experiments should be thoroughly planned and well-designed, and should avoid unnecessary use of animals. The reliability and reproducibility of animal experiments should also be considered. Whenever possible, alternative methods to animal experimentation should be adopted, such as in vitro experimentation, cadaveric studies, and computer simulations.

While much progress has been made on reducing animal experimentation there is a need for greater awareness of alternatives to animal experiments among scientists and easier access to advanced modeling technologies. Greater research is needed to define a roadmap that will lead to the elimination of all unnecessary animal experimentation and provide a framework for adoption of reliable alternative methodologies in biomedical research.

Acknowledgements

This research was funded by the Provincia Autonoma di Bolzano in the framework of LP 15/2020 (dgp 3174/2021).

Conflicts of interest statement

Authors declare no conflict of interest.

Author's contributions

MB: study conception, editing and critical revision of the manuscript; AKK, DP, GH, RB, Paul S, Peter S, RM, BF, NC, SM, LL, DD, GMT, MCE, MD, SM, Daniele M, GB, AD, KD, MCM, TB, MS, STC, Donald M, AM, AB, KLH, MK, LS, LL, GF: literature search, editing and critical revision of the manuscript. All authors have read and approved the final manuscript.

Contributor Information

INTERNATIONAL BIOETHICS STUDY GROUP : Derek Pheby , Gary Henehan , Richard Brown , Paul Sieving , Peter Sykora , Robert Marks , Benedetto Falsini , Natale Capodicasa , Stanislav Miertus , Lorenzo Lorusso , Gianluca Martino Tartaglia , Mahmut Cerkez Ergoren , Munis Dundar , Sandro Michelini , Daniele Malacarne , Tommaso Beccari , Michele Samaja , Matteo Bertelli , Donald Martin , Assunta Morresi , Ariola Bacu , Karen L. Herbst , Mykhaylo Kapustin , Liborio Stuppia , Ludovica Lumer , and Giampietro Farronato

Biomedical experimentation on animals

Biomedical experimentation dates back many years. Early experimentation included blood transfusions, vivisection (surgical procedures performed on conscious, living animals), and dissection of apes, dogs, and pigs. In present times testing on nonhuman animals is obligatory in codes of ethics for biomedical research. According to the Nuremberg Code adopted in 1947, any experiments carried out on human beings should be “designed and based on the results of animal research.” 1 The Helsinki Declaration, adopted in 1964 by the 13th World Medical Assembly, also notes that medical research on human subjects “should be based on laboratory and animal experiments or other scientifically established facts.” 2

Since 1940 there has been a new specialty in veterinary medicine: “laboratory animal science.” This makes clear the central role given to the use of animals in research, to the point of being a true paradigm.

There are several different purposes for which animals are used and killed in the field of biomedical research, including the following:

Study of disease

A number of procedures are aimed at studying how different diseases evolve. This is done by deliberately giving animals the disease that is being studied so as to observe how the disease and treatments might work in humans. A wide range of diseases are studied in this manner, such as digestive, neurological and genetic diseases. Animals are also used to study brain injury, spinal cord injury, Parkinson’s, AIDS, cancer, obesity, and many others. In order for these experiments to be carried out, animals are forced to endure terrible diseases, traumatic injury, force-feeding, burns, social deprivation, and exposure to toxic substances.

Development of new drugs

The discovery of new medicines generally involves four main steps:

1. Identification of potential drugs . First, new chemicals that may be useful as medicines are identified. The number of animals used in experiments during this phase makes up around 10% of the total number of animals who are used in the process of creating new medicines.

2. Testing new substances . Substances that are considered promising then go through further tests. This is by far the area in which the most animals are experimented on in the process of creating new medicines. Up to 80% of animals who are tested are used in this phase.

3. Safety testing . The safety of substances selected from the previous phase are then further tested. Generally more than 10% of the animals who are tested are used in this phase.

4. Refinement of the final product . The final phase in the development of new medicines involves studies on humans. In general, nonhuman animals are not experimented on at this point. 3

For a single drug, up to 3,000 animals may be used in various tests. Pain for these animals could often be controlled with medicine, but the medicines might interfere with the experiment. This is one reason why pain medication may not be given. In addition, experimenters may significantly prolong the suffering of animals by keeping them alive for a long time after they are fatally harmed by the experiments. Researchers keep these animals alive only because the death of animals during experiments may make the data less useful.

Animals used for experimentation

A wide variety of animals are used in research. They include the following:

Mice and rats . Mice and rats are used for a large number of purposes. They are commonly subjected to experiments on the reaction of mammals to an attack, intoxication, or experimental infection (parasitic, bacterial, or viral) and immunological, oncological (relating to tumors), teratological (abnormal physiological development), and embryological reactions and disorders. Mice are the animals most often used for analysis of human illnesses of genetic origin. Rats are also frequently used in nutritional, behavioral, and endocrinological studies. Mice and rats are used in experiments on cancer and nutrition, kidney disease, cholesterol and skin transplantation as well as many others.

Dogs and cats . Dogs are often used to study cardiovascular issues, CPR techniques, anemia, heart disease, and many other issues. Cats are commonly experimented on to study neurological diseases, cancer, genetic issues and also in studies of the immune system, among many others.

Rabbits . Rabbits are used to test the safety of drugs and vaccines, as well as to study transplants, cholesterol, product safety, and many other things that are mainly used in the production of antidotes, pharmacology, toxicology, teratogenicity, and reproduction.

Guinea pigs . Guinea pigs are used as models in immunological, pharmacological, and nutritional studies.

Hamsters . Hamsters are used for several purposes, including reproduction, cytogenesis, and immunology studies.

Birds, reptiles and frogs . Birds, reptiles and frogs are used in experiments involving diabetes, liver cancer, neurobiological issues and in many other experiments.

Cows . Cows are used in tests involving organ transplants, diabetes and heart disease, among others.

Primates . Primates are used in research on the subject of AIDS, Parkinson’s, anaesthesia, measles and many other diseases.

Most animals used by researchers have been bred specifically to be the subjects of experiments. However, other animals who are experimented on may be obtained from places such as shelters or by placing or answering ads. In many cases the animals are genetically modified, and the genetic modifications may cause them considerable suffering during their lives. Early death may also result due to some genetic modifications.

Examples of procedures

Below are just a few descriptions of the types of experiments and conditions 4 that animals are used in:

Tests for skin-sensitization . Guinea pigs are often used for this. Several doses of a chemical are placed on the skin of the guinea pig to see if a subsequent application causes a greater immune reaction than it does on the skin of a guinea pig who has not been previously exposed to the substance.

Tests on carcinogenicity . Animals such as rats are dosed with potentially carcinogenic substances for as long as two years and the tumors that grow are then studied. In other experiments, pregnant rabbits are dosed with a chemical during their entire pregnancy and their uterine contents are then studied to see if fetal death or altered growth occurred because of these chemicals.

Tests on heart conditions . Conditions such as heart attacks and strokes are induced artificially in dogs so they can be studied.

Paralysis tests . To create paralysis and spinal cord injuries, weights are dropped onto rodents.

Nausea tests . Electrodes are implanted in the intestines of dogs to make them vomit.

Headache tests . Migraine-like symptoms are artificially created in primates by using specific chemicals.

Toxicity tests . These tests assess, as their name suggests, the extent to which certain substances can be toxic. Some of these tests may cause the skin of the animals to crack and peel. Toxicity tests can also cause internal bleeding, vomiting, convulsions, and coma.

Metabolic studies . Animals have tubes implanted in their bile ducts.

Histocompatibility tests . In past histocompatibility tests, new materials were always evaluated on humans to see if they were biocompatible. Some time ago, this became unacceptable. Now, for a material to be considered biocompatible, it must pass through several stages. These are in vitro testing, in vivo testing (it is here that animals are used rather than humans), and in-use tests.

Medications . Animals are also used for bioavailability studies, which is research on the level or frequency with which a medicine or drug is absorbed or made available in body tissues or organs after having been administered.

Pathogenesis research . Transgenic animals are used in research on pathogenic mechanisms of illnesses as testing instruments for possible therapeutic compounds, and as in vivo instruments of validation for potential treatments.

Neurobiology . Animals, especially rats, are used to study the effects of surgery and nutrition on the brain.

The debate on animal experimentation

Defenders of animal experimentation claim that even though methods that do not harm animals may be developed, there are still a number of cases in which it is necessary to try drugs or procedures in living animals. Those opposing this view have argued that experiments on animals may not accurately reflect the effects these drugs will have in humans. Differences due to the species and breed of the animals used may cause the results to inaccurately predict effects in humans. Other problems can arise from the population of animals used being rather homogenous, whereas the population of humans is quite diverse. Differences between the way the tested materials are administered in the laboratory and the way they are ingested or absorbed by humans may also make the results inaccurate. 5

They further argue that even though humans and nonhuman animals may in many cases develop similar health problems, the physiological mechanisms are different. This would be the reason, they argue, why extrapolating data from animal experiments is not epistemologically sound. 6

Apart from these criticisms, and regardless of whether they are right or not, it can be pointed out that there is a sharp contrast between the ways humans and nonhuman animals are considered when it comes to biomedical research. We will see this in the following two sections.

Regulations are not making a difference

In a number of countries, there exist some regulations having to do with how animals can be used in experiments. However, these regulations, where they exist, commonly impose very few limitations on the use of nonhuman animals.

In the European Union, while animal experimentation for cosmetics is prohibited, experiments with scientific aims rarely prohibit the use of animals. The main current regulation in the EU is the Directive 2010/63/EU on the protection of animals used for scientific purposes . 7 Though it shows less disregard for nonhuman animals than virtually any other piece of regulation in this field, it does not question animal experimentation itself. It stipulates some requirements aimed at reducing the suffering endured by animals, but these can be outweighed by the requirements of the experiment, and it does not consider that the lives of animals are worthy of being preserved and protected. This is shown not only by the fact that animals are routinely killed in procedures, but also by the large numbers of animals who are killed simply because they were bred to be used in experiments but were not. They are killed anyway, and not only is this not prohibited, it is standard practice.

In the USA, animal experimentation is meant to be carried out in accordance with what the Animal Welfare Act of 1966 stipulates. 8 Despite the advances in our understanding of animal sentience and the arguments regarding the moral consideration of animals in recent decades, a law that is around half a century old still applies and has not been replaced by new legislation that provides far more significant protection to animals. To understand how poorly the Animal Welfare Act can provide any defense to animals, it is important to note that it excludes from its consideration animals such as rodents, which are the overwhelming majority of animals used in experimentation.

The enforcement of the Animal Welfare Act is assigned to the Animal Care division of the Animal and Plant Health Inspection Service (APHIS), which is a branch of the United States Department of Agriculture (USDA). This is not an animal protection body, but one that fully accepts the harm animals endure for human benefit.

It is similar in Canada, where animal experiments are meant to be carried out in accordance with the Canadian Council on Animal Care (CCAC) guiding principles.

In other countries such as Australia and Brazil, Animal Ethics Committees are the ones that can determine whether a certain procedure using nonhuman animals can be accepted or not. These committees commonly include supporters of experimentation, who are almost always their majority. Procedures are commonly accepted even if they cause significant harm to animals.

Finally, in some countries such as Japan, while there is a Law for Humane Treatment and Management of Animals, 9 in practice this is not meaningful at all, since there is no enforcement and there are no third-party agencies required to monitor what is done to the animals. It is assumed that experimenters will self-regulate, which is tantamount to having no regulation whatsoever.

All of this shows that animals used in biomedical testing will continue to have virtually no protection as long as laws accept that their lives and wellbeing have little value.

Animal ethics and experimentation

There are certain purposes for which the benefits of testing on nonhuman animals clearly do not outweigh the harms, because the harms are very significant in relation to trivial benefits (for example, cosmetics testing ). In other cases the benefits are greater and may outweigh the harms caused to the victims. Today different ethical theories exist with different conceptions of the criteria we should use in making decisions that affect testing subjects – human and nonhuman. 10 According to some theories, causing harm to an individual to benefit others is always morally unacceptable, so they would forbid experiments in these cases. According to other theories, we should instead consider the harms caused to some individuals alongside the benefits it gives to others, and give priority to the one that carries more weight. According to these views, experimentation in the latter cases would be acceptable. But as long as those defending this view do not apply it to humans but only to nonhuman animals they are displaying a speciesist bias and are not really accepting that ethical view consistently. In fact the question of the usefulness of in-use or clinical testing is rarely looked at from the benefits vs. harm perspective. It is simply assumed that nonhuman animals can be used as resources if it benefits humans. Speciesism should be rejected though: we must make our ethical evaluations of every practice by setting aside the species to which those involved belong, and considering only the interests they all have.

Further readings

Animal Procedures Committee (2003) Review of cost-benefit assessment in the use of animals in research , London: Home Office.

Baird, R. M. & Rosenbaum, S. E. (eds.) (1991) Animal experimentation: The moral issues , New York: Prometheus.

Balls, M. (1994) “Replacement of animal procedures: Alternatives in research, education and testing”, Lab Animal , 28, pp. 193-211.

Bockamp, E.; Maringer, M.; Spangeberg, C.; Fees, S.; Fraser, S.; Eshkind, L.; Oesch, F. & Zabel, B. (2002) “Of mice and models: Improved animal models for biomedical research”, Physiological Genomics , 11, pp. 115-132.

Bluemel, J.; Korte, S.; Schenck, E. & Weinbauer, G. (eds.) (2015) The nonhuman primate in nonclinical drug development and safety assessment , Amsterdam: Academic Press.

Caplan, A. L. (1983) “Beastly conduct: Ethical issues in animal experimentation”, Annals of the New York Academy of Sciences , 406, pp. 159-169.

Chader, G. G. (2002) “ Animal models in research on retinal degenerations: Past progress and future hope ”, Vision Research , 42, pp. 393-399 [accessed on 18 October 2013].

Cothran, H. (ed.) (2002) Animal experimentation: Opposing viewpoints , San Diego: Greenhaven.

DeGrazia, D. (1999) “The ethics of animal research: What are the prospects for agreement?”, Cambridge Quarterly of Healthcare Ethics , 8, pp. 23-34.

European Commission (2013) Seventh report on the statistics on the number of animals used for experimental and other scientific purposes in the member states of the European Union , Brussels: European Commission [accessed on 2 September 2016].

European Science Foundation Policy Briefing (2001) The use of animals in research , 2 nd ed., Strasbourg: European Science Foundation.

Frey, R. G. & Paton, W. (1989) “Vivisection, morals and medicine: An exchange”, in Regan, T. & Singer, P. (eds.) Animal rights and human obligations , Englewood Cliffs: Prentice Hall, pp. 223-226.

Gavin, S. L. & Herzog, H. A. (1992) “The ethical judgment of animal research”, Ethics & Behavior , 2, pp. 263-286.

Górska, P. (2000) “ Principles in laboratory animal research for experimental purposes ”, Medical Science Monitor , 6, pp. 171-180 [accessed on 22 June 2023].

Guillen, J. (ed.) (2013) Laboratory animals: Regulations and recommendations for global collaborative research , San Diego: Academic Press.

Kirk, A. D. (2003) “Crossing the bridge: Large animal models in translational transplantation research”, Immunological Reviews , 196, pp. 176-196.

Langley, G. (ed.) (1990) Animal experimentation: The consensus changes , London: MacMillan.

Matsuda, Y. (2004) “Recent trends in the number of laboratory animals used in Japan”, ATLA: Alternatives to Laboratory Animals , 32, suppl. 1A, pp. 299-301.

Ninomiya, H. & Inomata, T. (1998) “Current uses of laboratory animals in Japan and alternative methods in research, testing and education”, Applied Animal Behaviour Science , 59, pp. 219-25.

Orlans, F. B. (1998) “History and ethical regulation of animal experimentation: An international perspective”, in Kuhse, H. & Singer, P. A companion to bioethics , Oxford: Blackwell, pp. 399-410.

Rice, M. J. (2011) “The institutional review board is an impediment to human research: The result is more animal-based research”, Philosophy, Ethics, and Humanities in Medicine , 6.

Rowan, A. N. (1984) Of mice, models and men: A critical evaluation of animal research, Albany: State University of New York Press.

Russell, W. M. S. & Burch, R. L. (1959) The principles of humane experimental technique , London: Methuen.

Swart, J. A. A. (2004) “The wild animal as a research animal”, Journal of Agricultural and Environmental Ethics , 17, pp. 181-197.

Tannenbaum, J. & Rowan, A. N. (1985) “ Rethinking the morality of animal research ”, Hastings Center Report , 15 (5), pp. 32-43 [accessed on 22 September 2012].

1 Nuremberg Military Tribunals (1946-1949) Trials of war criminals before the Nuernberg Military Tribunals under Control Council Law no. 10 , Washington, D. C.: U. S. Government Printing Office.

2 World Medical Association (1964) Declaration of Helsinki: Recommendations guiding doctors in clinical research , Helsinki: 18 th WMA General Assembly [accessed on 30 October 2020].

3 See Nuffield Council on Bioethics (2005) The ethics of research involving animals , London: Nuffield Council on Bioethics, pp. 135-157 [accessed on 25 June 2020].

4 Botham, P. A.; Basketter, D. A.; Maurer, T.; Mueller, D.; Potokar, M. & Bontinck, W. J. (1991) “Skin sensitization—a critical review of predictive test methods in animals and man”, Food and Chemical Toxicology , 29, pp. 275-286. Lang, C. M. (2009) “The cost of animal research”, Lab Animal , 38, pp. 335-338. Royal Society (2004) The use of non-human animals in research: A guide for scientists , London: The Royal Society. MORI (2002) The use of animals in medical research study, conducted for the Coalition of Medical Progress, March – May 2002 , London: MORI. Monamy, V. (2009 [2000]) Animal experimentation: A guide to the issues , 2 nd ed., Cambridge University Press. Orlans, F. B. (1993) In the name of science: Issues in responsible animal experimentation , Oxford: Oxford University Press. Chow, P. K.; Ng, R. T. & Ogden, B. E. (2008) Using animal models in biomedical research: A primer for the investigator , Singapore: World Scientific. Committee to Update Science, Medicine, and Animals; Institute for Laboratory Animal Research; Division on Earth and Life Studies & National Research Council (2004) Science, medicine, and animals , Washington, D. C.: National Academies Press.

5 See for instance Sharpe, R. (1994) Science on trial: The human cost of animal experiments , Sheffield: Awareness Books; Croce, P. (1999) Vivisection or science: An investigation into testing drugs and safeguarding health , 2 nd ed., New York: Zed. See also: Greek, J. S. & Greek, R. (2000) Sacred cows and golden geese: The human cost of experiments on animals , New York: Continuum; (2003) Specious science: Why experiments on animals harm humans , New York: Bloomsbury Academic.

6 See LaFollette, H. & Shanks, N. (1997) Brute science: Dilemmas of animal experimentation , New York: Routledge; Shanks, N. & Greek, C. R (2009) Animal models in light of evolution , Boca Raton: Brown Walker.

7 European Parliament & Council of the European Union (2010) “ Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes ”, Official Journal of the European Union , 20.10.2010, pp. L. 276/33-79 [accessed on 12 February 2014].

8 National Agricultural Library (2013 [1966]) Animal Welfare Act , Washington, D. C.: National Agricultural Agriculture [accessed on 11 April 2021].

9 Shoji, K. (2008) “Japanese concept and government policy on animal welfare and animal experiments”, Alternatives to Animal Testing and Experimentation , 14, pp. 179-181. Takahashi-Omoe, H. & Omoe, K. (2007) “Animal experimentation in Japan: Regulatory processes and application for microbiological studies”, Comparative immunology, microbiology and infectious diseases , 30, pp. 225-246.

10 VanDeVeer, D. & Regan, T. (eds.) (1987) Health care ethics: An introduction , Philadelphia: Temple University Press. Clune, A. C. (1996) “Biomedical testing on nonhuman animals: An attempt at a ‘rapprochement’ between utilitarianism and theories of inherent value”, The Monist , 79, pp. 230-246. Singer, P. (1996) “Ethics and the limits of scientific freedom”, The Monist , 79, pp. 218-229.

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Can Animal Experimentation Be Justified?

Zaid shehryar compares two opposing views..

In his book Animal Liberation (1975), Peter Singer argues that the vast majority of animal experiments cannot be justified because they offer little new knowledge at a high cost of animal suffering. Singer also claims that such knowledge can be obtained by other means, without killing animals. By contrast, Carl Cohen offers a defense of animal experimentation. In his article, ‘The Case for the Use of Animals in Biomedical Research’ (available online), he argues that we have a strong obligation to carry out animal experiments in order to alleviate human suffering and extend human life. Here I will summarize both arguments, underscore potential weaknesses, and ultimately conclude that Singer’s position is more plausible than Cohen’s.

As a utilitarian, Singer grounds morality in the consequences of actions. Furthermore, he believes that a sufficient condition for a creature to have moral standing is its capacity to suffer, that is to say, to experience pain. The basic condition for this is sentience, the ability to experience sensations. Singer believes that, whenever possible, we should avoid causing unnecessary harm to sentient beings, and that many of the animals we experiment on evidently experience in this way. Although some animal testing has led to advances in medicine, Singer argues such progress can always be made in other ways. Adding insult to injury, animal experiments are often trivial or misconceived. Singer cites research going back to the nineteenth century. Most illustrative is a study that locked ten dogs in a hot chamber to induce heatstroke. This experiment caused great suffering to the dogs, and its main conclusion was that heatstroke victims should be cooled.

Singer argues that our willingness to tolerate such morally egregious behavior can be explained only by our ‘speciesism’ – an irrational moral bias against nonhuman animals analogous to racism. Singer goes further, asking why the interests of rational beings (us) should matter if the interests of non-rational beings (other animals) do not? He also wonders what special features human beings must possess to earn their exalted moral status. He argues that there is no morally relevant category that includes all humans but excludes all other animals. For instance, some animals are more intelligent than some people with severe learning disabilities; yet since it is immoral to subject these people to painful experimentation, it must also be wrong to subject these animals to it. Other proposed features allowing the moral superiority of human beings include our capacity for abstract reasoning, language, and introspection. Yet not all people possess these abilities – but it would still be immoral to subject them to painful scientific experiments. In fact, it is immoral to do so for the same reason that it is immoral to hurt nonhuman animals: because of the evil of unnecessary suffering.

Although Singer’s argument is strong, Cohen disagrees with it. He argues that animals have no rights. He claims rights exist only within a community of moral agents, because such rights can only be defended by agents who make moral claims against each other. Humans confront moral choices, and, unlike animals, we consequently lay down codes of conduct for ourselves. But in conducting research on animals, we are not violating their rights, Cohen claims, since there is nothing to violate, since no rights have been established by mutual consent. To state that all animals have the ‘right to life’ or to ethical consideration merely because they have interests is unwarranted. Similarly, obligations result from the relationships we form with other people. A teacher’s obligation arises from the role she plays within her community, for example. However, since animals are outside our moral community and lack such special relationships, their interests can be sacrificed for the welfare of people. Cohen also denies that the pleasures and pains experienced by animals require the same moral consideration as those of humans because animals lack autonomy and membership in the moral community. Singer’s charge of speciesism therefore fails, he says. Indeed, speciesism is ‘essential to right conduct’, since those who fail to make the relevant moral distinction between humans and nonhumans will fail to recognize their real moral duties.

Cohen’s argument is liable to criticism. Consider its syllogistic form:

(1) If an animal does not share our moral community, then it does not deserve our moral consideration.

(2) Animals are excluded from our moral community.

(3) Therefore, animals are not due moral consideration.

Although it is logically valid, this argument is not good. Both premises (1) and (2) are false. First, it is not demonstrated (or true) that those outside our moral community are excluded from our moral consideration. If that were so, human cultures with sufficiently different and far-away traditions would not be entitled to our moral consideration. Being not under our moral consideration, they would then be entitled to conduct any kind of atrocity without being liable to moral criticism from us. That is an untenable conclusion.

Second, it is not the case that nonhuman animals are excluded from our moral community. Cohen might argue that animals are not moral agents: perhaps – but it’s important to remember that under his definition of ‘moral agency’ (as being an acknowledged part of a moral community), neither are many humans. Most people are simply doing their best to navigate their environment with limited information and inchoate moral instincts. Not everyone has time to study ethics, epistemology, or the human condition. Some folks live like bears, apart from the rest of humanity, eating berries and salmon, trying their best. Yet they are still worthy of my consideration. They are conscious, after all, just as I am. They can be happy, and they can suffer.

Since the evil of suffering is the most salient feature in this debate, Singer’s argument is decisive. So we should stop experimenting on animals.

© Zaid Shehryar 2023

Zaid Shehryar is a philosophical medical researcher from Brooklyn, bridging the realms of philosophical thought and scientific inquiry.

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Oxford Centre for Animal Ethics

Ethics of animal experimentation.

In 1947, Oxford don C. S. Lewis commented that it was “the rarest thing in the world to hear a rational discussion of vivisection”. The aim of this project in partnership with Cruelty Free International is to provide just that: a rational discussion of the ethics of using animals in research.

The first stage of the project was the publication of the Centre’s independent report on the ethics of the use of animals in research.  It is entitled Normalising the Unthinkable: The Ethics of Using Animals in Research .

The second stage was an international Summer School on the Ethics of Using Animals in Research.  The Summer School was held at St Stephen’s House, Oxford on 26-29 July 2015. Papers were invited from academics world-wide on any aspect relating to the ethics of animal experimentation, including philosophical and religious ethics, historical, legal, psychological, and sociological perspectives, the morality of various types of research, the use of alternatives, the confinement of animals in laboratories, and the effectiveness of current controls and future legislation. Contributors were asked to consider responding to the methodology and conclusions of the report in their contributions to the Summer School.

A short film about the Summer School is available below.

The programme of the Summer School is available  here .

The project is being arranged by the Oxford Centre for Animal Ethics in partnership with Cruelty Free International . The Centre is very grateful to Cruelty Free International for its sponsorship of academic work on this subject.

St Stephen’s House  is an Anglican Theological College and a Hall of the University of Oxford.

For more information please contact Clair Linzey at [email protected] .