The Evolutionary Psychology of Morality and Law: From Darwin and Huxley to Lieberman and Patrick

The moral judgments that we enforce in our laws are often rooted in deep emotions such as fear, anger, love, compassion, and disgust.  And so, for example, it has been an almost universal practice to legally prohibit or punish those forms of sexual activity that people have generally found disgusting--such as prostitution, pornography, incest, sodomy, and bestiality, some of which have been regarded as "crimes against nature."  But recently, particularly in the more liberal societies around the world, there has been a movement towards loosening or even eliminating the legal repression of sexual conduct that many people find disgusting.  A dramatic illustration of this is the removal of legal sanctions against homosexuality and the legalization of same-sex marriage.

This raises big questions about how to explain this, what this shows about the role of instinctive emotions in law, and whether we should see these changes in the law as moral progress.  Debra Lieberman and Carlton Patrick help us to think through these questions in their book Objection: Disgust, Morality, and the Law (Oxford University Press, 2018).  Lieberman is one of the leading researchers in evolutionary psychology--as developed by Leda Cosmides and John Tooby--and she is best known for her research supporting Edward Westermarck's evolutionary theory of incest avoidance and the incest taboo.  Patrick is a professor of legal studies interested in the application of evolutionary psychology to the law.

Lieberman and Patrick argue that what we see in the laws that are based on disgust is "the general logic of what is gross to me is wrong for you" (178).  They explain the evolutionary psychology of disgust as an evolved instinctive aversion to harmful food (deciding what to eat), to pathogens and infectious agents (deciding what to touch), and to sexual activity that will not produce healthy, viable offspring (deciding with whom to have sex).  So, when we taste, touch, or see the cues for bad food, diseased agents, or perverse sexuality, we say "that's disgusting."  This evolved instinct for feeling disgust can then be turned to support moral disgust that is expressed in law: what you're doing is really bad because it grosses me out, and so there should be a law against it.  It's so disgusting to me to imagine gay men having anal sex that this must be wrong, and they should be legally punished.

Once they have explained these links between disgust, morality, and the law, Lieberman and Patrick contend that this shows the irrationality of allowing disgust to shape our moral and legal judgments; and they conclude by recommending that disgust should never be a standard for morality or law, because our moral and legal norms should be based on purely logical and abstract reasoning free from the influence of disgust and all other emotions.

I am not confident that I fully understand what they are saying here, because they don't elaborate what they mean by advocating morality and law based purely on "logic and abstract reasoning," so that "we need not rely on biologically driven intuitions," and we can separate human biology from moral philosophy (190, 193, 204)  But as far as I can tell, they are supporting, if only implicitly, a Kantian rationalist view of ethics as transcending human biological nature, which denies the naturalist view of ethics defended by Hume, Darwin, and Westermarck.  This is confusing, because if I am correct in this interpretation, Lieberman and Patrick in their book are contradicting what Lieberman has argued some years ago about the biological basis of morality in the moral sentiments, as explained by Westermarck (Lieberman, Tooby, and Cosmides 2003).

As I have indicated in some previous posts (here, and here,), many evolutionary psychologists have followed Thomas Huxley's lead (in his lecture on "Evolution and Ethics") in rejecting Darwin's evolutionary account of morality in The Descent of Man.  Because of the "moral indifference of nature," Huxley argued, one could never derive moral values from natural facts.  He concluded "that the ethical process of society depends, not on imitating the cosmic process, still less in running away from it, but in combating it," and thus building "an artificial world within the cosmos."  Human morality belongs to a transcendent realm of cultural artifice that is beyond the natural realm of evolved human nature.

In 1975, in his book Sociobiology, Edward O. Wilson tried to revive the position of Darwin and Westermarck that ethics could be fully explained as rooted in evolved human nature, in the moral emotions or sentiments of the human animal.  Immediately after the publication of that book, moral philosophers took Huxley's position that ethics transcended human biology because ethics was an autonomous creation of human reason.  For example, Thomas Nagel argued that ethics was a rational activity that transcended human biology.  Ethics is "the result of a human capacity to subject innate or conditioned prereflective motivational and behavioral patterns to criticism and revision, and to create new forms of conduct."  "Biology may tell us about perceptual and motivational starting points, but in its present state it has little bearing on the thinking process by which these starting points are transcended" (Nagel 1978, 204).

In 1998, in his book Consilience, Wilson elaborated his defense of a Darwinian science of ethics that would take an empiricist view of ethics as rooted in the moral sentiments, as opposed to the transcendentalist view of ethics as a product of pure reason.  Many evolutionary psychologists were disturbed by Wilson's suggestion that a biological science of natural facts could explain the ethics of moral values.  After all, they insisted, isn't there a radical dichotomy between science and ethics, facts and values, is and ought?  Isn't it a "naturalistic fallacy" to think that one can infer a moral ought from a natural is?

Lieberman and Patrick make this same appeal to the is/ought dichotomy (or "Hume's Law") in claiming that it is fallacy to move from the "is" of human nature to the "ought" of human ethics.  They do not consider the possibility that this is based on a misinterpretation of Hume, or that Hume actually defended a naturalistic view of ethics as rooted in a natural moral sense that was embraced by Darwin and Westermarck.  Moreover, they do not reflect on the possibility that there is no fallacy in viewing ethics as a system of hypothetical imperatives based on human nature (a point that I have developed here.)

Lieberman and Patrick also echo Nagel's Kantian rationalism in their claim that the "logic and abstract reasoning" of ethics transcends human biology.  They write:

"Humans have science, the capacity for logic and abstract reasoning, and a vast sea of knowledge from which to draw.  We need not rely on biologically driven intuitions, like disgust, to shape society" (190).

". . . Unlike other animals, humans are endowed with an extraordinary gift: the capacity to ascertain and investigate our own biological and psychological makeup, and even more importantly, the capacity to evaluate it--to reinforce the parts of it that we deem worthy, and to try our best to moderate the parts of it that we deem undesirable.  As far as we know, we're the only species on the planet that has this capacity, and we're also the only species with an institutional infrastructure that is powerful enough either to value the intuition and license it, or to move society away from these deep-seated intuitions.  It is a an extraordinary gift and, accordingly, should be exercised with great responsibility.  The starting point of this responsibility is to separate biology from philosophy; to disentangle the reliably developing tendencies that evolution has equipped us with from the state of the world that we seek to effectuate" (204).

". . . The goal of the law is not to optimize or maximize the survival and reproduction of individuals or their genes, but rather to move the populace toward a desired state of affairs" (205).

Notice that the ultimate standard here for morality and law is to move away from the "undesirable" and towards the "desired state of affairs." Although Lieberman and Patrick repeatedly point to this goal of "a desirable state of affairs," they never explain what this means, or what it implies about morality and law (6, 13, 18-19, 79, 81, 126, 195, 202, 204-205).

Are they assuming that the good is the desirable?  If so, does this mean that morality cannot arise from pure "logic and abstract reasoning" without the motivational impetus of desire?  Can morality be understood as rooted in the natural desires of evolved human nature?  If so, does that indicate how the science of ethics could be a biological science?

I will be writing more posts on Lieberman and Patrick's book.


REFERENCES

Lieberman, Debra, John Tooby, and Leda Cosmides. 2003. "Does Morality Have a Biological Basis? An Empirical Test of the Factors Governing Moral Sentiments Relating to Incest." Proceedings of the Royal Society of London B 270: 819-826.

Nagel, Thomas. 1978. "Ethics as an Autonomous Theoretical Subject." In Gunther S. Stent, ed., Morality as a Biological Phenomenon: The Presuppositions of Sociobiological Research, 198-205. Berkeley: University of California Press.

Evolutionary Psychology Denies Finnis's Metaphysical Natural Law and Confirms Locke's Human Natural Law

Evolution and Human Behavior has published (online, but not yet in print) an article by Carlton Patrick--"Evolution Is the Source, and the Undoing, of Natural Law."  Patrick is a lawyer and a Professor of Legal Studies at the University of Central Florida.  

Previously, I have written about the book that Patrick coauthored with Debra Lieberman--Objection: Disgust, Morality, and the Law (2018).  I said that the main argument of Lieberman and Patrick in that book is a syllogism:  since evolutionary psychology shows that moral emotions like disgust are irrational in ways that are dangerous to society, and since the law should be based on rational principles rather than irrational emotions, disgust (and other moral emotions) should be excluded from the law.  I said that that syllogism is false, because the premise that moral emotions like disgust are utterly irrational is false.  I argued that research in evolutionary moral psychology shows that moral judgment always combines reason and emotion in a complex interaction.  Consequently, moral judgment cannot be properly explained by either a purely emotivist theory or a purely rationalist theory.  In explaining moral judgment in this way as the conjunction of reason and emotion, evolutionary moral psychology confirms the tradition of naturalist moral philosophy that stretches from Aristotle and Thomas Aquinas to David Hume and Adam Smith and then to Charles Darwin and Edward Westermarck. 

Playing off the title of Patrick's new article, I would argue that evolution is the source of natural law as interpreted by Thomas Aquinas and John Locke and the undoing of natural law as interpreted by John Finnis and Robert George.  Patrick's mistake is in assuming that Finnis's (and George's) Kantian distortion of natural law as based on some metaphysical or cosmic order of reason beyond human nature is the correct interpretation of traditional natural law.  He thus ignores the fact that the natural law as understood by people like Aquinas and Locke is rooted in human biological nature in a way that can be confirmed by evolutionary moral psychology.

Patrick begins his article by identifying the proponents of the idea of natural law as including Aristotle, Aquinas, Grotius, Locke, Dworkin, Finnis, and George.  He then singles out Finnis as "the father of the modern natural law argument," who insists that natural law must be founded on "moral objectivity, be it established by God, the universe, or some metaphysical source."  In this way, natural law is based on some "supernatural or metaphysical explanations" that transcend human nature.  For Finnis, this metaphysical order dictates certain "basic goods"--life, health, knowledge, play, friendship, religion, and aesthetic experience--that are "fundamental, underived, irreducible."

Patrick can then argue that evolutionary psychology refutes this metaphysical conception of natural law.  He explains:

". . . when we talk about morality, we are not talking about a cosmic mandate but rather a set of species-wide psychological instincts that are a part of human nature.  These instincts evolved because, over evolutionary time, they helped our ancestors to navigate the highly social world of the evolutionary milieu.  Although there are differing views, most evolutionary scholars agree that the general functions of morality are to avoid, navigate, and resolve conflicts of interest in social interactions" (3).

So, if Finnis's metaphysical interpretation of natural law as founded on a "cosmic mandate" is correct, then evolutionary psychology refutes natural law.  

There are two problems here, however.  Patrick simply assumes without proof that Finnis's metaphysical interpretation is correct.  And he fails to consider the possibility that there are better interpretations of natural law as founded on human biological nature that could be supported by evolutionary psychology.

There have been many critics of Finnis's interpretation of natural law--including Henry Veatch, Ralph McInerny, Russell Hittinger, and Anthony Lisska.  Patrick does not mention, must less answer, these critics.  In a series of posts, I have indicated why I agree with the critics.  The primary criticism of Finnis is that his version of natural law is natural law without nature, because he rejects the traditional understanding of natural law as rooted in human nature--in the natural desires or natural inclinations of human beings.  Finnis actually admits this when he dismisses "the rather unhappy term 'natural law.'"  He doesn't like the term "natural law" because it implies that it is rooted in human nature, and that is what he denies (Natural Law and Natural Rights [1980], 35, 198, 280, 374).

Moreover, Patrick does not see that the traditional understanding of natural law is rooted in the principle (as stated by Aristotle, Aquinas, and Locke) that "the good is the desirable," which supports natural law as founded on those natural desires distinctive to human biological nature.  This corresponds to what Patrick calls those "species-wide psychological instincts that are part of human nature," which are studied by evolutionary psychologists.  I have defended this position in Darwinian Natural Right: The Biological Ethics of Human Nature (1998).

Patrick also does not see that natural rights in Locke's state of nature correspond to the natural instincts in what evolutionary psychologists call the "environment of evolutionary adaptedness" (EEA).  I have written about this in various posts (here, here, and here).

This leads me to conclude that while evolutionary psychology denies Finnis's metaphysical natural law, it confirms Locke's human natural law.

Evolutionary Moral Psychology Combines Reason and Emotion: Correcting Lieberman and Patrick on Disgust

The main argument of Lieberman and Patrick in Objection is a syllogism:  since evolutionary psychology shows that moral emotions like disgust are irrational in ways that are dangerous to society, and since the law should be based on rational principles rather than irrational emotions, disgust (and other moral emotions) should be excluded from the law.

That syllogism is false, because the premise that moral emotions like disgust are utterly irrational is false.  Research in evolutionary moral psychology shows that moral judgment always combines reason and emotion in a complex interaction.  Consequently, moral judgment cannot be properly explained by either a purely emotivist theory or a purely rationalist theory.  In explaining moral judgment in this way as the conjunction of reason and emotion, evolutionary moral psychology confirms the tradition of naturalist moral philosophy that stretches from Aristotle and Thomas Aquinas to David Hume and Adam Smith and then to Charles Darwin and Edward Westermarck.  (Here I am drawing some passages from some previous posts here, here, here, and here,)

Lieberman and Patrick begin their book with Jonathan Haidt's famous scenario about Julie and Mark deciding to engage in incest, which Haidt calls "a harmless taboo" story:

"Julie and Mark, who are sister and brother, are traveling together in France.  They are both on summer vacation from college.  One night they are staying alone in a cabin near the beach.  They decide that it would be interesting and fun if they tried making love.  At the very least it would be a new experience for each of them.  Julie is already taking birth control pills, but Mark uses a condom too, just to be safe.  They both enjoy it, but they decide not to do it again.  They keep that night as a special secret between them, which makes them feel even closer to each other.  So what do you think about this?  Was it wrong for them to have sex?" (Haidt 2012, 38)

Originally, Haidt and his collaborators presented this story to 30 undergraduate students at the University of Virginia.  24 of the students said that Julie and Mark were wrong to do this.  They were then asked why was this wrong.  They struggled to give a reason, and when they did, the interviewer would challenge what they said.  Haidt reports:

"Most people who hear the above story immediately say that it was wrong for the siblings to make love, and they then begin searching for reasons.  They point out the dangers of inbreeding, only to remember that Julie and Mark used two forms of birth control.  They argue that Julie and Mark will be hurt, perhaps emotionally, even though the story makes it clear that no harm befell them.  Eventually, many people say something like, 'I don't know, I can't explain it, I just know it's wrong'" (Haidt 2001, 814).

Notice what Haidt did here.  First, he implicitly assumed that the best rational principle of moral judgment is "no harm."  Then, he carefully wrote the scenario about Julie and Mark to exclude the possibility of harm from their incest--either the harm of inbreeding for their offspring or the emotional harm to their relationship as siblings.  He could then tell the students that this harmless conduct could not be morally condemned and that condemning this conduct as disgusting is irrational because disgust is not a rational principle of moral judgment. 

Some of Haidt's critics have challenged him on all these points (Jacobson 2012; May 2018; Royzman et al. 2015).  Weren't the students who condemned Julie and Mark correct in thinking that sibling incest is likely to be harmful?  Even if they could avoid pregnancy and the harm of inbreeding, isn't it implausible that they could avoid emotional harm to themselves.  In his scenario, Haidt says that Julie and Mark thought making love would be "interesting and fun," and that they could keep it as a "special secret between them" that would make them "feel even closer to each other."  But isn't that unrealistic?  And isn't it likely that most of the students found Haidt's scenario unbelievable?

In fact, when Royzman and his colleagues conducted their own experiment in asking students to respond to Haidt's story of Julie and Mark, the students were allowed to express their disbelief in the claim that Julie and Mark could engage in incest without harm.  Most of the students could not believe that sex between siblings could occur without some emotional harm to the siblings.  In Haidt's experiment, he refused to accept this by forcing the students to agree with the stipulated claim in his scenario that Julie and Mark were not emotionally harmed by their incest.

Haidt's students show that the moral condemnation of incest will be both emotional and rational: there will be an emotional expression of disgust with incest that depends on a rational judgment of what constitutes incest.  Consider, for example, how Haidt's students might have responded to a scenario in which Julie and Mark were cousins who fell in love.  Many of the students might have felt no disgust if they thought that sex between cousins need not be considered incest.  Or if they were told that Julie and Mark were stepsiblings who had been reared in different families, this also might have led some of them to conclude that this was not incest.  Or what if they were told that Mark's wife had died, and Julie was his sister-in-law?  Here our moral emotion of disgust depends on our cognitive judgment of what counts as incest.

This illustrates how we reason with our emotions: we argue ourselves into and out of our moral emotions by judging whether those emotions are a justified response to the circumstances.  Not many years ago, most people might have felt a disgust with interracial marriage and homosexual marriage comparable to their disgust with incest.  But now this reaction has been weakened by the judgment that there is no harm in such marriages.  Legislators and judges must debate these questions in deciding what kinds of marriage are permitted.

And so, for example, as I have indicated in my recent posts on Justice Kennedy's opinion in the Obergefell v. Hodges Supreme Court decision upholding same-sex marriage as a constitutional right, much of the debate in this case turned on whether same-sex marriage would be harmful for children or harmful in weakening the institution of heterosexual marriage.  This required a rational judgment of the empirical evidence as to whether same-sex marriage was likely or not to be harmful.  The acceptance of Kennedy's opinion depends on whether one agrees with him that the evidence suggests that same-sex marriage is not harmful.

Remarkably, when Lieberman and Patrick briefly discuss the Supreme Court cases on homosexuality, they are almost completely silent about this debate over the evidence as to whether homosexuality is harmful or not.  They thus convey the impression that the disgust with homosexuality has no rational basis at all (185-88).  Oddly, it is only in a endnote that they admit that there might be a rational policy debate here: "To be fair, a few dissenting justices briefly discuss the interest of states in encouraging natural procreation within the unit that provides the best atmosphere for raising children (i.e., traditional marriage).  And regardless of whether this is a strong policy argument, it is, at least, a policy argument" (233, n. 41).  (I am wondering whether they were forced to add this endnote to satisfy one of the anonymous referees of their book manuscript for Oxford University Press.) 

In another endnote, they admit that Kurt Gray and other researchers "might be correct" in seeing evidence that judgments of harm are always involved in moral emotions, because when people see something as wrong, they almost certainly see it as harmful (224, n. 31).  (Was this endnote added to satisfy another referee?)  Amazingly, Lieberman and Patrick don't recognize that this contradicts their main argument--that disgust is an utterly irrational emotion that does not involve any rational judgment that disgusting conduct might be harmful.  (See Gray et al. 2014, 2015; Schein et al. 2016.)

In trying to prove the irrationality of disgust and other moral emotions, Lieberman and Patrick often cite the research of Haidt and others that apparently shows that "incidental" disgust--disgust that has nothing directly to do with the object of moral evaluation--influences moral judgment.  So, for example, if you create a bad smell in a room--by using fart spray--and then ask people in the room to evaluate homosexuality, they will rate it as more morally wrong than subjects in a room without the foul odor.  But then in a parenthetical sentence, Lieberman and Patrick remark: "We should note that recent analyses have questioned, with good reason, the robustness of the results from those incidental-disgust studies, but the original researchers maintain that their conclusions as to the effects were valid" (136; 224, n. 32).  If you read the articles they cite, you will see that Landy and Goodwin (2015) have shown that the research claiming that incidental disgust strongly influences moral judgment has not been replicated, and that there has been a strong publication bias, in that many of the experiments showing no influence of incidental disgust on moral judgment have not been published.

In response to research like this that contradicts his original argument that moral emotions like disgust have no rational basis, Haidt has begun to change his mind, and he has begun to recognize that moral judgment really does require a complex interaction of reason and emotion.  In The Righteous Mind, he speaks of the "useless dichotomy between cognition and emotion," and he says that "emotions are not dumb," because "emotions are a kind of information processing," and therefore emotion and reasoning are two forms of cognition (Haidt 2012, 44-48).

When we respond to some situation with a moral emotion like disgust, we must cognitively interpret that situation, which requires some kind of reasoning, even if the reasoning is quick, unconscious, and implicit rather than consciously deliberate.  So when Haidt's students read his scenario about Julie and Mark, the students had to engage in some reasoning to decide whether Haidt's claim that their incestuous liaison could be harmless was realistic or not.  Most of them decided that this was not realistic, and as a consequence of this rational judgment of likely harm, their interpretation of the situation produced an intuitive emotion of moral disgust.

Consequently, we can be persuaded--by ourselves or by others--to change our moral emotions when we change our judgments about the social world around us.  This has happened in the debate over homosexuality and same-sex marriage.  For a long time, the great majority of people have felt disgust towards homosexuals because they thought homosexuality was harmful.  If you have any doubt about the opposition to homosexuality being based on the perception that it is harmful, just read Anita Bryant's The Anita Bryant Story: The Survival of Our Nation's Families and the Threat of Militant Homosexuality (1977).  The subtitle tells it all.  Bryant was a popular American singer and advertising voice for Florida orange juice.  In 1977, she began a campaign against a gay rights ordinance in Miami, which soon spread around the country.  Although she had some victories, she provoked a national backlash against her that destroyed her career, because her exaggerated fear of "the threat of militant homosexuality" was not persuasive with many people.  Now, more and more people are deciding that homosexuality is not harmful after all, and consequently they no longer find it disgusting enough to legally suppress it.

Not seeing this, Lieberman and Patrick cannot explain why the law in many societies has recently become more tolerant of the homosexual life, because they cannot recognize how the moral emotion of disgust depends upon rational judgments about the reality of homosexuality in our social world.


REFERENCES

Bryant, Anita. 1977. The Anita Bryant Story: The Survival of Our Nation's Families and the Threat of Militant Homosexuality. Old Tappan, NJ: Fleming H. Revell Company.

Gray, Kurt, Chelsea Schein, and Adrian Ward. 2014. "The Myth of Harmless Wrongs in Moral Cognition: Automatic Dyadic Completion From Sin to Suffering." Journal of Experimental Psychology: General 143: 1600-1615.

Gray, Kurt, and Chelsea Schein. 2015. "The Myth of the Harmless Wrong." The New York Times, January 30.

Haidt, Jonathan. 2001. "The Emotional Dog and Its Rational Tail: A Social Intuitionist Approach to Moral Judgment." Psychological Review 108: 814-34.

Haidt, Jonathan. 2012. The Righteous Mind; Why Good People Are Divided by Politics and Religion. New York: Pantheon.

Jacobson, Daniel. 2012. "Moral Dumbfoundng and Moral Stupefaction." In Oxford Studies in Normative Ethics, ed. Mark Timmons, 289-315.  Oxford: Oxford University Press.

May, Joshua. 2018. Regard for Reason in the Moral Mind. Oxford: Oxford University Press.

Royzman, Edward B., Kwanwoo Kim, and Robert F. Leeman. 2015. "The Curious Tale of Julie and Mark: Unraveling the Moral Dumbfounding Effect." Judgment and Decision Making 10: 296-313.

Schein, Chelsea, Ryan S. Ritter, and Kurt Gray. 2016. "Harm Mediates the Disgust-Immorality Link." Emotion 16: 862-76.

The Evolutionary Psychology of the Harm Principle: Are Lieberman and Patrick Libertarians?

I have long been puzzled as to why evolutionary psychologists--like Jon Haidt, Leda Cosmides, and John Tooby--do not affirm explicitly the libertarianism that is implied in what they say about the evolved human nature of morality and politics.  I have written about that here, here, here, and here.

I continue to be puzzled by that same question in trying to interpret Debra Lieberman and Carlton Patrick's Objection: Disgust, Morality, and the Law.  In arguing for reducing or even eliminating the influence of moral disgust in the law, they repeatedly appeal to the principle of no harm--that people should not be legally punished for conduct that affects only themselves and does not harm others (4-5, 12-13, 117, 123, 125-27, 130-31, 139, 141, 147-48, 163, 187, 203, 205).  But except for one casual reference, they do not identify this as the famous principle of John Stuart Mill's On Liberty (see 203, 235, n. 23).

In On Liberty, Mill contends that "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others."  This has been called not only the "harm principle" but also the "nonaggression axiom"--the idea that a legal order is a mutual nonaggression pact in which all agree not to injure others by force or fraud, but with the understanding that all have the right to defend themselves against the aggression of others.  This idea has an ancient history beginning with the ancient Greek philosophers Lycophron and Epicurus.  In modern liberal thought, it was affirmed by John Locke that in the state of nature "being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions," and that all have the "executive power of the law of nature" to punish those who initiate aggression against others.  This same principle has been reaffirmed by a long line of classical liberals, such as Herbert Spencer: "Every man is free to do that which he wills, provided he infringes not the equal freedom of any other man."

In the entry on "John Stuart Mill" in The Encyclopedia of Libertarianism, Aeon Skoble writes: "The general principle that conduct that does not harm others should not be legally proscribed virtually defines libertarianism."  If that is so, then Lieberman and Patrick are libertarians in their promotion of that principle.  It's also notable that The Encyclopedia of Libertarianism has an entry on "Evolutionary Psychology" written by Cosmides and Tooby, which includes a criticism of Marxist communist regimes for denying the reality of evolved human nature by assuming "that human desires, emotions, and motivations are infinitely plastic social constructions that can be easily molded into any form."  (I have written about Cosmides and Tooby as libertarian critics of socialism here.)

In this video, being interviewed by Michael Shermer, Lieberman says that her evolutionary psychology of disgust provides a "platform for promoting freedom," for "just freedom in general" (go to 1:22:40), because it teaches us how "free trade" overcomes Us/Theming, so that we allow people to live as they please in their various groups as long as they do not harm others.  This is her clearest statement of her libertarianism.

The Incoherence of Evolutionary Psychology's Kantian Transcendentalist Morality: Carlton Patrick and Peter DeScioli

In Consilience: The Unity of Knowledge (1998), Edward O. Wilson recognized that crucial for his unification of all knowledge was a biological account of ethics as rooted in evolved human nature.  He rightly noted that in doing this, he was following in the tradition of naturalistic ethics that stretches from Aristotle to David Hume to Adam Smith and to Charles Darwin.  He was also right to see this naturalistic tradition of ethics as being "empiricist" in contrast to the "transcendentalist" ethics of those thinkers like Immanuel Kant who look to a transcendent realm of moral freedom beyond the natural world of human inclinations and experience.  Since I agree with Wilson about this, it always seems strange to me that so many evolutionary psychologists have rejected Wilson's reasoning in favor of a Kantian transcendentalist view of morality, even though this contradicts any evolutionary explanation of morality as grounded in evolved human nature, which makes their account of morality incoherent.

For example, a few months ago, I wrote about Carlton Patrick's article--"Evolution Is the Source, and the Undoing, of Natural Law"--in which he assumed that John Finnis was correct in his Kantian interpretation of natural law as based on some "supernatural or metaphysical explanations" that transcend human nature.  Patrick then showed how evolutionary psychology explains that "when we talk about morality, we are not talking about a cosmic mandate but rather a set of species-wide psychological instincts that are a part of human nature."  But in thus refuting Finnis's Kantian distortion of natural law, Patrick ignored the fact that the natural law as understood by people like Thomas Aquinas and John Locke is rooted in human biological nature in a way that can be confirmed by evolutionary moral psychology.

I have also pointed out how Patrick and his coauthor Debra Lieberman have supported a Kantian rationalist view of ethics as transcending human biological nature, which denies the naturalist view of ethics defended by Locke, Darwin, and Westermarck.

Peter DeScioli is another example of an evolutionary psychologist who accepts Kant's transcendentalist morality, while still developing an evolutionary account of morality that contradicts that Kantian transcendentalism (DeScioli 2016; DeScioli and Kurzban 2009, 2013, 2018; Kurzban, DeScioli, and Fein 2012).  DeScioli repeatedly refers to Kant's Groundwork for the Metaphysics of Morals as showing how moral judgment must depend on the "categorical imperatives" of a transcendental morality (see, for example, DeScioli and Kurzban 2013, 479-480; and Kurzban et al. 2012).  He also endorses George Jackson Mivart's Kantian critique of Darwin's evolutionary moral psychology in The Descent of Man (DeScioli and Kurzban 2013, 479; Mivart 1893, 1973).  Mivart insisted on a Kantian separation between nature and morality.  Although the human body could be explained as a natural product of biological evolution, Mivart contended, the human soul was a supernatural product of divine creation.  And as an expression of the soul's transcendence of nature, human morality manifested a uniquely human freedom from natural causality.

In the Groundwork, Kant posits a radical dualism that separates reality into two metaphysical realms.  Judging what is the case belongs to the "phenomenal" realm of nature, but judging what ought to be belongs to the "noumenal" realm of freedom (Kant 1959, 3-5, 30, 44-45, 67-74, 80 [Academie edition, 387-89, 413, 426-28, 448-56, 460-62]).  The distinction in English between is and ought corresponds to Kant's distinction in German between sein and sollen.  For Kant, the natural world is governed by causal laws that can be understood by natural science; and in this world there can be no free will, because every event must be determined by a causal mechanism.  By contrast, in our moral experience, we praise and blame people in accordance with a moral law that transcends nature and is thus unknowable by natural science; and in this moral world we must assume free will, because moral judgment would be impossible unless we assumed that people were capable of freely choosing to obey or disobey the moral law.  As moral agents, we obey categorical imperatives of what ought to be, but this ought expresses a moral necessity that has no place in nature.  "When we have the course of nature alone in view, ought has no meaning whatsoever" (Kant 1965, 473).  As moral agents, human beings transcend the empirical realm of nature and enter a transcendent realm of freedom that belongs to them as rational beings not governed by the laws of nature.

Kant's separation of is and ought treats morality as an autonomous realm of experience governed by its own internal logic with no reference to anything in human nature such as natural desires and inclinations and the natural pursuit of happiness.  The human pursuit of happiness is not truly moral because it is governed by the empirical hypothetical imperatives of prudence--if you desire to be happy, then you must cultivate the moral and intellectual virtues--but not by the categorical imperatives of pure moral reason--you must obey the moral law without regard to your natural desires for happiness.

This puts Kant in opposition to the ethical naturalists like Aristotle, Aquinas, Locke, and Hume, who say that the human good is the desirable, that human morality is the pursuit of happiness, and that the natural moral law corresponds to the order of the natural desires of human nature.

When Darwin developed his evolutionary theory of morality, he adopted the ethical naturalist position rather than a Kantian dualism.  When he began his account of the moral sense in The Descent of Man, he quoted a passage from Kant's Critique of Practical Reason about how the word ought is one of the noblest traits of human beings.  But in the immediately following passage of Kant's book, Kant said this experience of the moral ought shows us "man as belonging to two worlds" (Kant 1956, 90).  Darwin, however, denied this Kantian dualism by indicating that he would approach morality "exclusively from the side of natural history," and he identified the power of the word ought as expressing instinctive moral emotion--"the deep feeling of right or duty" (2004, 120-21, 134, 136, 140, 147, 680).

DeScioli says that his evolutionary theory of morality is on the side of Kant rather than Darwin, because he accepts Kant's claim "that morality consists of 'categorical imperatives,' a set of actions that are morally wrong regardless of the goals these actions are intended to achieve," and DeScioli believes that laboratory research "has found that people often show Kantian moral thinking, focusing on specific actions rather than expected consequences" (DeScioli and Kurzban 2013, 479).   

DeScioli claims that the Kantian morality of categorical imperatives is shown clearly in how most people think about the Trolley Dilemma.  Imagine that you see a runaway trolley speeding down a track, and five people who have somehow become bound to the track will be killed.  You see that there is a switch that will turn the trolley onto a sidetrack and save the lives of the five people.  Unfortunately, however, there is one person bound to the sidetrack who will be killed if you throw the switch.  Should you throw the switch--killing one person but saving five?

Now imagine that you are on a footbridge over the tracks.  You see the runaway trolley and the five people who will be killed if the trolley is not stopped.  There is no switch to divert the trolley onto a sidetrack.  You could jump onto the track and try to stop it.  But let's say that you are such a small person that you're unlikely to stop it.  You notice, however, that there is a fat man standing near you, and if you push him onto the tracks, he will probably stop the trolley, but he will be killed.  Should you push the fat man--killing one person but saving five?

Oh sure, as I have indicated in my previous posts on the Trolley Dilemma, this looks like a silly cartoon.  But it does illustrate the kind of dilemma that some people have faced (perhaps in war), where killing one or a few people might save the lives of many. 

When people are asked about these two trolley scenarios, most will say that they would pull the switch but would not push the fat man.  This might seem strange since most are willing to kill one person to save five in the switch case but not in the footbridge case.  What's the difference between the two cases?

(Actually, in one realistic simulation of the switch case, 5 of 7 individuals froze in fear and refused to throw the switch.)

As DeScioli indicates, the most plausible explanation has been offered by John Mikhail (2011), who says that what we see here is an intuitive moral understanding of the Principle of Double Effect.  Thomas Aquinas stated this principle as part of his natural law jurisprudence.  To reconcile the prohibition of intentional killing with the right to kill in self-defense, Aquinas explained: "Nothing prevents one action having two effects, only one of which is intended, and the other of which is unintended. . . . Therefore, one's action in defending oneself can have two effects: saving one's life and slaying the aggressor.  And so such acts of self-defense, as one intends by them to preserve one's life, do not have the character of being unlawful, since it is natural for everything to keep itself in existence as far as possible" (Summa Theologica, II-II, q. 64, a. 7).  Mikhail sees a general principle here: "the principle holds that an otherwise prohibited action, such as battery or homicide, which has both good and bad effects may be permissible if the prohibited act itself is not directly intended, the good but not the bad effects are directly intended, the good effects outweigh the bad effects, and no morally preferable alternative is available" (Mikhail 2011, 148-49).

Mikhail applies this Principle of Double Effect to explain how most people distinguish the switch case from the footbridge case in the Trolley Dilemma.  If there is no morally preferable alternative, most people would pull the switch to intentionally save the five lives, while foreseeing but not directly intending the death of the one person on the sidetrack.  We know that the killing is not intended, because if the person on the sidetrack could escape and save his life, the bystander who pulled the switch would be pleased with this outcome.  By contrast, to push the fat man off the footbridge would be a directly intended killing; and we know that because if the fat man could run off the track to save his life, the intended outcome of the bystander who pushed him would not be achieved.

Mikhail sees this Principle of Double Effect as one manifestation of an "intuitive jurisprudence" rooted in "a common moral nature" and "a common sociobiological instinct" that illustrates the naturally evolved moral sense identified by Darwin in The Descent of Man (Mikhail 2011, 57, 148, 172; Darwin 2004, 132-38).

I don't see how this conforms to Kant's metaphysical morality.  Kant never speaks about the Principle of Double Effect.  And he clearly denies that moral judgment can be rooted in any instinctive moral sense of human nature, because pure moral reasoning belongs to a noumenal realm of pure moral reason that transcends the empirical reality of nature.

And yet, DeScioli insists that how people judge the trolley dilemma manifests the categorical imperatives of Kantian morality.  "Immanuel Kant would argue . . . that when humans face this dilemma, they should not kill one to save five because there is an inviolable moral rule against killing that cannot be broken regardless of the consequences" (Kurzban, DeScioli, and Fein 2012, 323).  In the footbridge version of the trolley dilemma, most people do seem to judge that in that situation, it is wrong to kill one person to save five people.  But in the switch version, most people judge that in that situation, it is right to kill one person to save five.   And so they do not believe in a Kantian categorical imperative that "there is an inviolable moral rule against killing" in all situations, as DeScioli asserts.  Rather, they believe that the rightness or wrongness of killing depends upon the situation.  So that in a situation where one must kill one person to save five people, and that killing is not directly intended, that killing is not wrong.  But in a situation where one directly intends to kill one person to save five people, that killing is wrong.  

Similarly, in a situation where killing an attacker is the only way to save one's life, that killing in self-defense is not wrong, because one is not directly intending the killing, as indicated by the fact that if the attacker were to retreat or surrender, one would not kill him.  A comparable moral principle of the law of just war is that combatants must not directly intend to target innocent people for attack, although innocent people might die as an unintended side-effect of directly attacking military targets.  Combatants may attack and kill enemy combatants who threaten them, but if those enemy combatants surrender, then they may not be killed.  

Here we see that Kant's categorical imperative (never kill) fails, because it does not allow for prudence in recognizing the variability in our moral judgments of right and wrong as applied to variable situations.

In a recent article in Evolution and Human Behavior, DeScioli seems to pull away from his earlier attempts to ground an evolutionary theory of morality and law in Kantian moral philosophy (De Scioli 2023).  He says nothing about Kant.  He argues that moral rules and laws evolved as a strategy for choosing sides in conflicts by impartial rules of action.  And this would seem to be grounded not in Kant's categorical imperatives but in the hypothetical imperatives of Thomistic and Lockean natural law as rooted in evolved human nature.  I will comment on that article in my next post.

REFERENCES

Darwin, Charles. 2004. The Descent of Man.  Penguin Classics.

DeScioli, Peter.  2016.  "The Side-Taking Hypothesis for Moral Judgment."  Current Opinion in Psychology 7:23-27.

DeScioli, Peter. 2023.  "On the Origin of Laws by Natural Selection."  Evolution and Human Behavior 44: 195-209.

DeScioli, Peter, and Robert Kurzban.  2009.  "Mysteries of Morality."  Cognition 112: 281-99.

DeScioli, Peter, and Robert Kurzban.  2013.  "A Solution to the Mysteries of Morality."  Psychological Bulletin 139: 477-496.

DeScioli, Peter, and Robert Kurzan.  2018.  "Morality Is for Choosing Sides."  In K. Gray and J. Graham, eds., Atlas of Moral Psychology, 177-185.  New York: Guildford Press.

Kant, Immanuel.  1956.  Critique of Practical Reason.  Trans. Lewis White Beck.  Indianapolis: Bobbs-Merrill.

Kant, Immanuel.  1959.  Foundations of the Metaphysics of Morals.  Trans. Lewis White Beck.  Indianapolis: Bobbs-Merrill.

Kant, Immanuel.  1965.  Critique of Pure Reason.  Trans. Norman Kemp Smith.  New York: St. Martin's Press.

Kurzban, Robert, Peter DeScioli, and Daniel Fein.  2012.  "Hamilton vs. Kant: Pitting Adaptations for Altruism Against Adaptations for Moral Judgment."  Evolution and Human Nature 33: 323-333.

Mikhail, John.  2011.  Elements of Moral Cognition: Rawls' Linguistic Analogy and the Cognitive Science of Moral and Legal Judgment.  New York: Cambridge University Press.

Mivart, St. George Jackson. 1893.  "Evolution in Professor Huxley."  The Popular Science Monthly 44: 319-33.

Mivart, St. George Jackson.  1973.  "Darwin's Descent of Man."  In David Hull, ed., Darwin and His Critics, 354-84.  Chicago: University of Chicago Press.

Patrick, Carlton.  2023.  "Evolution Is the Source, and the Undoing, of Natural Law."  Evolution and Human Behavior 44: 175-183.

Wilson, Edward O.  1998.  Consilience: The Unity of Knowledge.  New York:  Knopf.