Thursday, May 23, 2019

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 hereherehere, 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.


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.

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