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.
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.