EVOLUTIONARY ETHICS

Evolutionary ethics rests on the idea that ethics expresses a natural moral sense that has been shaped by evolutionary history. It is a scientific understanding of ethics as founded in human biological nature.

The first full development of evolutionary ethics came from Charles Darwin (1809–1882) and Herbert Spencer (1820–1903) in the nineteenth century. At the beginning of the twentieth century, the Darwinian theory of ethics was renewed and deepened by Edward Westermarck (1862–1939). At the end of the twentieth century, this Darwinian tradition of ethical philosophy was reformulated by Edward O. Wilson, Robert McShea, Frans de Waal, and others.

Philosophers arguing over the ultimate grounds of ethics have been divided into Aristotelian naturalists and Platonic transcendentalists. The transcendentalists find the ground of ethics in some reality beyond human nature, while the naturalists explain ethics as grounded in human nature itself. In this enduring debate, proponents of evolutionary ethics belong to the Aristotelian tradition of ethical naturalism, while their strongest opponents belong to the Platonic tradition of ethical transcendentalism. (Of course, Aristotelians who reject evolutionary reasoning would also reject evolutionary ethics.)

The history of evolutionary ethics can be divided into three periods, with Darwin initiating the first period, Westermarck the second, and Wilson the third.

Darwin's View

As part of his theory of the evolution of life by natural selection, Darwin wanted to explain the evolution of human morality. From his reading of Adam Smith (1723–1790), David Hume (1711–1776), and other philosophers who saw morality as rooted in moral emotions or a moral sense, Darwin concluded that this moral sense could be understood as a product of natural selection. As social animals, human beings evolved to have social instincts. As rational animals, human beings evolved the rational capacity to reflect on their social instincts and formulate those moral rules that would satisfy their social instincts. Human survival and reproduction required that parents care for their offspring, and the social nature of human beings could be explained as an extension of parental feelings of sympathy to embrace ever larger groups of individuals. In his Descent of Man (1871), Darwin concluded: "Ultimately our moral sense or conscience becomes a highly complex sentiment—originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit" (Darwin 1871, Vol. 1, pp. 165–166).

Herbert Spencer (1820–1903) generally agreed with Darwin's evolutionary ethics, yet Spencer put more emphasis than did Darwin on evolution through the inheritance of acquired traits. And unlike Darwin, Spencer saw all of evolutionary history as moving toward a pre-determined end of perfection in which human societies would become so cooperative that they would achieve perpetual peace.

When The Descent of Man was published, Darwin's naturalistic theory of morality was attacked by biologist George Jackson Mivart (1827–1900), who claimed that there was an absolute separation between nature and morality. Although Darwin's theory of evolution could explain the natural origins of the human body, Mivart insisted, it could not explain the human soul as a supernatural product of divine creation, and therefore it could not explain human morality, which depended on the soul's freedom from natural causality. Mivart followed the lead of Immanuel Kant (1724–1804) in arguing that the realm of moral duty must be separated from the realm of natural causality, thus adopting a version of the distinction between values and facts.

This dispute between Darwin and Mivart shows the conflict between the naturalistic tradition of moral thought and the transcendentalist tradition that runs throughout moral philosophy and throughout the debate over evolutionary ethics. According to Plato (in The Republic), one cannot know what is truly good until one sees that all of the diverse goods of life are only imperfect imitations of the Idea of the Good, which is universal, absolute, and eternal. In Plato's theological version of this teaching, God as the Creator of the cosmos is said to be a providential caretaker of human affairs who judges human beings after death, rewarding the good and punishing the bad. Aristotle (in the Nicomachean Ethics) rejected this Platonic Idea of the Good, because he could not see any sense in saying there is a transcendent good separated from all the diverse natural goods that human beings seek. Looking to the common-sense experience of human beings, Aristotle thought that the ultimate end for which human beings act is happiness, and happiness would be the human flourishing that comes from the harmonious satisfaction of human desires over a whole life. Like Smith and Hume, Darwin followed the Aristotelian tradition in rooting morality in natural desires and emotions. Like Kant, Mivart followed the Platonic tradition in positing a moral ought belonging to a transcendent world of moral freedom beyond the empirical world of natural causes.

Thomas Huxley (1825–1895), one of Darwin's most fervent supporters, initially defended Darwin's evolutionary ethics against Mivart's criticisms. But eventually, in his 1893 lecture on "Evolution and Ethics," Huxley adopted Mivart's transcendentalist position. Because of the "moral indifference of nature," Huxley declared, one could never derive moral values from natural facts. He argued 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 (Paradis and Williams 1989, pp. 117, 141)."

Westermarck's Views

After Huxley's attack, Darwin's naturalistic ethics was kept alive in the early-twentieth century by philosophers such as Westermarck. In his History of Human Marriage (1889), Westermarck explained the desires for marriage and family life as founded in moral emotions that had been shaped by natural selection as part of the biological nature of human beings. His most famous idea was his Darwinian explanation of the incest taboo, which can be summarized in three propositions. First inbreeding tends to produce physical and mental deficiencies in the resultant offspring, which lowers their fitness in the Darwinian struggle for existence. Second, as a result of the deleterious effects of inbreeding, natural selection has favored the mental disposition to feel an aversion toward sexual mating with those with whom one has been an intimate associate from early childhood. Third this natural aversion to incest has been expressed culturally as an incest taboo. Consequently, in all human societies, there is a strong tendency to prohibit fathers marrying daughters, mothers marrying sons, and brothers marrying sisters, although there is more variation across societies in the rules governing the marriage of cousins and others outside the nuclear family. (In 1995 Anthropologist Arthur Wolf surveyed the growing evidence confirming Westermarck's Darwinian theory of incest avoidance.)

Westermarck believed all of the moral emotions could be ultimately explained in the same way he had explained the abhorrence of incest. As animals formed by natural selection for social life, humans are inclined to feel negative about conduct perceived as painful, and positive toward conduct perceived as pleasurable. The mental dispositions to feel such emotions evolved in animals by natural selection because these emotions promote survival and reproductive fitness: Resentment helps to remove dangers, and kindly emotion helps to secure benefits. For the more intelligent animals, these dispositions have become conscious desires to punish enemies and reward friends.

Moral disapproval, Westermarck argued, is a form of resentment, and moral approval is a form of kindly emotion. In contrast to the non-moral emotions, however, the moral emotions show apparent impartiality. (Here he shows the influence of Smith's idea that the moral sentiments arise when we take the perspective of the impartial spectator.) If a person feels anger toward an enemy or gratitude toward a friend, these are private emotions that express personal interests. In contrast, if a person declares some conduct of a friend or enemy to be good or bad, he or she implicitly assumes that the conduct is good or bad regardless of the fact that the person in question is a friend or enemy. This is because it is assumed that when conduct is determined to be good or bad, a person would apply the same judgment to other people acting the same way in similar circumstances, independently of the effect on that individual. This apparent impartiality characterizes the moral emotions, Westermarck explained, because "society is the birth-place of the moral consciousness" (1932, p. 109). Moral rules originated as tribal customs that expressed the emotions of an entire society rather than the personal emotions of particular individuals. Thus moral rules arise as customary generalizations of emotional tendencies to feel approval for conduct that causes pleasure and disapproval for conduct that causes pain.

Although Westermarck stressed the moral emotions as the ultimate motivation for ethics, he also recognized the importance of reason in ethical judgment. "The influence of intellectual considerations upon moral judgments is certainly immense" (1932, p. 147). Emotions, including the moral emotions, depend upon beliefs, and those beliefs can be either true or false. For example, a person might feel the moral emotion of disapproval toward another that he or she believes has injured a friend, but if that same person discovers by reflection that an injury was accidental and not intentional, or that an action did not actually cause any injury at all, the disapproval vanishes. Moreover, because moral judgments are generalizations of emotional tendencies, these judgments depend upon the inductive use of human reason in reflecting on emotional experience.

Wilson's View

By the 1970s, however, there was little interest in the ethical naturalism of people such as Westermarck, and the transcendentalist tradition had largely conquered the intellectual world of philosophers and social scientists. Ethics and politics were assumed to belong to an autonomous human realm of reason and culture that transcended biological nature. This could be explained as a reasonable reaction against the morally repulsive conduct associated with "Social Darwinism" in the first half of the twentieth century.

This also explains why the publication of Wilson's book Sociobiology in 1975 provoked great controversy. Wilson defined sociobiology as the scientific study of the biological bases of the social behavior of all animals, including human beings. On the first page of the book, he claimed that ethics was rooted in human biology. He asserted that the deepest human intuitions of right and wrong are guided by the emotional control centers of the brain, which evolved through natural selection to help the human animal exploit opportunities and avoid threats in the natural environment.

One of the first serious responses to Wilson's proposal for sociobiological ethics was a conference in Berlin in 1977 titled "Biology and Morals." The material from this conference was later published as a book edited by Gunther Stent. In his introduction, Stent began by contrasting the "idealistic ethics advocated by Plato" and the "naturalistic ethics advocated by Aristotle." He suggested that those people who belonged to the idealistic tradition would reject Wilson's sociobiological ethics, while those belonging to the naturalistic tradition would be more inclined to accept it.

In this book Thomas Nagel, a philosopher, showed the reaction of the Platonic transcendentalist. He rejected sociobiological ethics because it failed to see that ethics is "an autonomous theoretical subject" (Nagel 1978) such as mathematics that belongs to a transcendent realm of pure logic. On the other side of this debate, Robert McShea, a political scientist, independently welcomed Wilson's sociobiological ethics as providing scientific confirmation for the insight of Aristotle and Hume that ethics is rooted in the emotions and desires of human biological nature (Mcshea 1978). All writing on this subject that followed, as of 2004, fell into one of these two intellectual camps.

The transcendentalist critics of evolutionary ethics include most of the leading proponents of evolutionary psychology, which applies Darwin's theory of evolution in explaining the human mind as an adaptation of human nature as shaped in evolutionary history. Evolutionary psychologists such as George Williams (1989) claim that ethics cannot be rooted in human nature because of the unbridgeable gulf between the selfishness of our natural inclinations and the selflessness of our moral duties. As the only rational and cultural animals, human beings are able to suppress their natural desires and enter a transcendent realm of pure moral duty. Like Huxley, Williams and other theorists of evolutionary psychology reject Wilson's sociobiological ethics because they think that ethics requires a transcendence of human biology through culture and reason. Unlike Wilson and Darwin, therefore, the proponents of evolutionary psychology do not believe that biological science can account for the moral conduct of human beings.

Objections and Replies

There are at least three major objections to this Darwinist view of morality. One common criticism of evolutionary ethics is that it promotes genetic determinism. If all choices are ultimately determined by genetic causes, that would seem to deny that human actions can be freely chosen, which would deny the fundamental presupposition of moral judgment that people can be held responsible for their moral choices.

But if genetic determinism means that behavior is rigidly predetermined by genetic mechanisms, so that neither individual learning nor social culture has any influence, then defenders of evolutionary ethics are not genetic determinists. What the genes prescribe, Wilson would say, is certain propensities to learn some behaviors more easily than others. Human nature, Wilson explains in his 1998 book Consilience, is not a product of genes alone or of culture alone. Rather, human nature is constituted by "the epigenetic rules, the hereditary regularities of mental development that bias cultural evolution in one direction as opposed to another, and thus connect the genes to culture" (p. 164). Consequently human behavior is highly variable across individuals and across societies, but the genetic nature of the human species is manifested in the general pattern of behavior.

So, for example, the natural human propensity to incest avoidance is actually a propensity to learn a sexual aversion to those with whom one has been raised. The precise character of the incest taboo will vary greatly across societies depending on the diversity in family life and kinship systems. For instance some societies will forbid marrying first cousins, while others will not. Yet the tendency to forbid the marriage of brother and sister or of parent and child will be universal or almost universal. Moreover one can deliberate about the rules of incest avoidance by reflecting on the relevant facts and emotions. When the incest taboo is formally enacted in marriage law, legislators must decide what counts as incest and what does not.

Proponents of evolutionary ethics would say that people are not absolutely free of the causal regularities of nature. Exercising such absolute freedom from nature—acting as an uncaused cause—is possible only for God. But human beings are still morally responsible for their actions because of the uniquely human capacity for reflecting on motives and circumstances and acting in the light of those reflections.

A second criticism of evolutionary ethics is that it promotes a crudely emotivist view of ethics as merely an expression of arbitrary emotions. After all, from the first paragraph of Sociobiology, Wilson speaks of ethics as controlled by "the emotional control centers in the hypothalamus and limbic system of the brain" (1975, p. 31). He repeatedly identifies the ultimate foundation for ethical codes as "our strongest feelings of right and wrong" (Ruse and Wilson 1994, p. 422). "Murder is wrong" might be just another way of saying "I don't like murder." Does that deny the sense of moral obligation as something more than just an expression of personal feelings?

People might also wonder how an emotivist ethics would handle the response of those with deviant emotions, such as that of psychopaths who do not show the normal emotions of guilt, shame, or sympathy. How can society condemn them if there are no objective moral norms beyond emotion? Moreover, how does society resolve the emotional conflicts that normally arise within and between individuals? How does society rank some emotional desires as higher than others? Such problems lead many philosophers to dismiss emotivist ethics as incoherent.

In reply to this criticism, the defender of evolutionary ethics might again consider the case of the incest taboo. If Westermarck is right, moral condemnation of incest arises from an emotion of sexual aversion toward those with whom one has been raised in early childhood. This personal emotion of disgust becomes a moral emotion of disapprobation when generalizing emotional experience into an impartial social rule: People judge that incest is bad not just for themselves but for all members of society in similar circumstances. Reason plays a part in generalizing these emotions. By reason people must formulate what counts as incest. Generally society condemns the sexual union of siblings or of parents and children. But whether one condemns the marriage of cousins will depend on the circumstances of kinship and judgments about whether the consequences are good or bad for society.

Normally most human beings will feel no sexual attraction to their closest kin. Those who do will usually feel a conflict between their sexual desire and their fear of violating a social norm that expresses deep emotions, and this fear of social blame will usually override their sexual interest. Those who do violate the incest taboo will be punished by a disapproving society. A few human beings might feel no emotional resistance to incest at all. They might be psychopathic in lacking the moral emotions of guilt and shame that are normal for most people. If so then society will treat them as moral strangers, as people who are not restrained by social persuasion, and who therefore must be treated as social predators.

The main point for those favoring evolutionary ethics is that although the moral emotions are relative to the human species, they are not arbitrary. One can easily imagine that if other animal species were to develop enough intellectual ability to formulate moral rules, some of them might proclaim incest to be a moral duty, because the advantages of inbreeding for bonding between kin might be greater than the disadvantages. But human beings are naturally inclined to acquire an incest taboo, and therefore to condemn those individuals who deviate from this central tendency of the species.

Emphasizing emotion in moral experience denies the transcendentalist claim that morality depends on pure reason alone. The 1994 work of Antonio Damasio and that of other neuroscientists suggests that the emotional control centers of the brain are essential for normal moral judgment. Psychopathic serial killers can torture and murder their victims without feeling any remorse. Yet they are often highly intelligent people who suffer no deficits in their cognitive capacities. Their moral depravity comes not from any mistakes in logical reasoning but from their emotional poverty in not feeling moral emotions such as guilt, shame, love, and sympathy.

A third objection to evolutionary ethics is that it fails to recognize the logical gap between is and ought, between natural facts and moral values. Determining that something is the case does not say that it ought to be so. A scientific description of a behavior is not the same as a moral prescription for that behavior.

In reply to this objection, proponents of evolutionary ethics might agree with Hume's interpretation of the is/ought dichotomy, which claims that pure reasoning about factual information cannot by itself move people to moral judgments. Moral motivation requires moral emotions. Those moral emotions, however, manifest propensities of human nature that are open to scientific study.

The incest taboo illustrates this. The factual information about inbreeding does not by itself dictate any moral judgment. If society did not feel moral emotions of disgust toward inbreeding among human beings, it would not be condemned as immoral. Even the factual information about the deleterious effects of inbreeding would not incur moral condemnation if people did not feel sympathy for human suffering.

The move from facts to values is not logical but psychological. Because people have the human nature that they do, which includes propensities to moral emotions, they predictably react to certain facts with strong feelings of approval or disapproval, and the generalization of those feelings across a society constitutes moral experience.

If society decided that evolutionary ethics was correct about ethics being grounded in emotions, this would influence assessment of the technologies of emotion. People might decide, as many science fiction authors have suggested, that robots could become moral beings only if they could feel human emotions. Society might also wonder about the moral consequences of new biomedical technologies for manipulating emotions through drugs and other means. People might question whether the technology of birth control could obviate the need for the incest taboo.

LARRY ARNHART

SEE ALSO Aristotle and Aristotelianism;Darwin, Charles;Determinism;Emotion;Evolution-Creationism Debate;Plato;Sociobiology;Spencer, Herbert.

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