PHILOSOPHERS USED to say that all their endeavours were merely a footnote to Plato. In ethics this is still largely true.
Modern moral philosophers are mostly divided into consequentialists and deontologists. Both see their task as uncovering the nature of an a priori Platonic ideal, that cosequentialists take to be the Good and deontologists the Right. But neither side doubts that their purpose is to lay down absolute principals that are universally applicable to all human beings.
This approach extinguish-ed the commensense ideas of sophists like Glaucon in Plato's Republic, who held that morality is a matter of social convention. The view was revived again by David Hume but the world continues to prefer the grandiose notions of Immanuel Kant, who argued that the only reason that we are sentient is to put into practice the categorical imperative: act only on the maxim that you would will to be a universal law. But such an approach denies the obvious fact that what people think is good or right depends on the culture in which they were raised. In recent years, sociobiologists have followed E.O. Wilson in reviving yet again the idea that it is possible to approach ethics as a scientist, by exploring the biological and social facts on which our moral intuitions are based. Such facts are contingent. They would have been otherwise if biological and social history had taken a different course. Moral behaviour in chimpanzees and baboons differs from moral behaviour in humans because their biological history differs from ours. Moral behaviour in other human societies differs from moral behaviour in our society because their social history differs from ours. In ancient Athens, I would perhaps have chased after adolescent boys like Socrates. In ante-bellum Virginia, I would probably have been ready to keep slaves like Thomas Jefferson. Such frank relativism is too much for many to swallow. But those who wish to preach that one society is better than another are not entitled to appeal to naturalistic theories of ethics. …