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. More recently, a number of evolutionary biologists, including
Richard Alexander,
Robert Trivers, and
George Williams, have argued for a different relation between ethics and evolution. In Alexander's words: “Ethical questions, and the study of morality or concepts of justice and right and wrong, derive solely from the existence of
conflicts of interest.” The latter, in turn, are inevitable consequences of genetic
individuality. Alexander argued that "Because morality involves conflicts of interest, it cannot easily be generalized into a universal despite virtually continual efforts by utilitarian philosophers to do that; morality does not derive its meaning from sets of universals or undeniable facts." Rather, he argued, The two major contributions that evolutionary biology may be able to make to this problem are, first, to justify and promote the conscious realization that it is conflicts of interest concentrated at the individual level which lead to ethical questions, and, second, to help identify the nature and intensity of the conflicts of interest involved in specific cases. As an example of genetic conflict, parents are selected to direct their time and resources equally among their offspring, but any particular child is more strongly related to itself than to any of its siblings, and so will desire a greater amount of parental investment than either parent is selected to give. A consequence of this
parent-offspring conflict is that natural selection is unable to instill a universal sense of what is "just" or "fair" with regard to treatment of siblings, since behavior that is most conducive to propagation of the parents' genes differs from what is most favorable for the child's genes. Alexander noted that a focus on conflicts of interest is common among biologists and other non-philosophers, but that "many moral philosophers do not approach the problem of morality and ethics as if it arose as an effort to resolve conflicts of interests." He defined what he called "moral systems" as societal (
not evolved) responses to conflicts of interest. Among other examples, he cited societal rules or laws imposing monogamy. The behavioral conflicts that are addressed by such rules have their evolutionary origin in the (genetic)
sexual conflict between men and women. ==Descriptive evolutionary ethics==