By what steps, historically, did morality emerge? Our remote ancestors evolved into social animals. Sociality requires, among other things, restraints on disruptive sexual, hostile, aggressive, vengeful, and acquisitive behavior. Since we are innately social and not social by convention, we can assume the biological evolution of the emotional equipment – numerous predispositions to want, fear, feel anxious or secure – required for social living, just as we can assume cultural evolution of various means to control antisocial behavior and reinforce the prosocial kind. Small clans consisting, say, of several extended families whose members cooperated in hunting, gathering, defense, and child-rearing could not exist without a combination of innate and social restraints on individual behavior.
I shall argue for a naturalistic theory of morality, by which I do not mean the definitional claims G.E. Moore sought to refute, but a broader and more complex theory that maintains that a sufficient understanding of human nature, history, and culture can fully explain morality; that nothing is left hanging. A theory that coherently brings together the needed biological, psychological, and cultural facts I shall call a philosophical anthropology; it is a theory that:
1) takes the good for humans – both an ultimate good (if there is any) and other important goods – to depend on human nature;
2) argues that a rudimentary but improving scientific and philosophical theory of human nature now exists, and thus denies that people are “essenceless”;
3) takes this theory to be evolutionary and historical, making the question “How did morality originate?” pivotal for ethical theory, but leaves open the empirical question of the relative importance of biological and cultural evolution; and
4) takes the origin of the moral ideas to be explainable in terms of human nature and history.