Evolutionary ethics is a field of inquiry that explores how evolutionary theory might bear on our understanding of ethics or morality. The range of issues investigated by evolutionary ethics is quite broad. Supporters of evolutionary ethics have claimed that it has important implications in the fields of descriptive ethics, normative ethics, and metaethics.
Descriptive evolutionary ethics consists of biological approaches to morality based on the alleged role of evolution in shaping human psychology and behavior. Such approaches may be based in scientific fields such as evolutionary psychology, sociobiology, or ethology, and seek to explain certain human moral behaviors, capacities, and tendencies in evolutionary terms. For example, the nearly universal belief that incest is morally wrong might be explained as an evolutionary adaptation that furthered human survival.
Normative (or prescriptive) evolutionary ethics, by contrast, seeks not to explain moral behavior, but to justify or debunk certain normative ethical theories or claims. For instance, some proponents of normative evolutionary ethics have argued that evolutionary theory undermines certain widely held views of humans' moral superiority over other animals.
Evolutionary metaethics asks how evolutionary theory bears on theories of ethical discourse, the question of whether objective moral values exist, and the possibility of objective moral knowledge. For example, some evolutionary ethicists have appealed to evolutionary theory to defend various forms of moral anti-realism (the claim, roughly, that objective moral facts do not exist) and moral skepticism.
History
The first notable attempt to explore links between evolution and ethics was made by Charles Darwin in The Descent of Man (1871). In Chapters IV and V of that work Darwin set out to explain the origin of human morality in order to show that there was no absolute gap between man and animals. Darwin sought to show how a refined moral sense, or conscience, could have developed through a natural evolutionary process that began with social instincts rooted in our nature as social animals.
Not long after the publication of Darwin's The Descent of Man, evolutionary ethics took a very different—and far more dubious—turn in the form of Social Darwinism. Leading Social Darwinists such as Herbert Spencer and William Graham Sumner sought to apply the lessons of biological evolution to social and political life. Just as in nature, they claimed, progress occurs through a ruthless process of competitive struggle and "survival of the fittest," so human progress will occur only if government allows unrestricted business competition and makes no effort to protect the "weak" or "unfit" by means of social welfare laws. Critics such as Thomas Henry Huxley, G. E. Moore, William James, Charles Sanders Peirce, and John Dewey roundly criticized such attempts to draw ethical and political lessons from Darwinism, and by the early decades of the twentieth century Social Darwinism was widely viewed as discredited.
The modern revival of evolutionary ethics owes much to E. O. Wilson's 1975 book, Sociobiology: The New Synthesis. In that work, Wilson argues that there is a genetic basis for a wide variety of human and nonhuman social behaviors. In recent decades, evolutionary ethics has become a lively topic of debate in both scientific and philosophical circles.
Descriptive evolutionary ethics
The most widely accepted form of evolutionary ethics is descriptive evolutionary ethics. Descriptive evolutionary ethics seeks to explain various kinds of moral phenomena wholly or partly in genetic terms. Ethical topics addressed include altruistic behaviors, conservation ethics, an innate sense of fairness, a capacity for normative guidance, feelings of kindness or love, self-sacrifice, incest-avoidance, parental care, in-group loyalty, monogamy, feelings related to competitiveness and retribution, moral "cheating," and hypocrisy.
A key issue in evolutionary psychology has been how altruistic feelings and behaviors could have evolved, in both humans and nonhumans, when the process of natural selection is based on the multiplication over time only of those genes that adapt better to changes in the environment of the species. Theories addressing this have included kin selection, group selection, and reciprocal altruism (both direct and indirect, and on a society-wide scale). Descriptive evolutionary ethicists have also debated whether various types of moral phenomena should be seen as adaptations which have evolved because of their direct adaptive benefits, or spin-offs that evolved as side-effects of adaptive behaviors.