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. Even the wishy-washy liberal doctrine that all societies are equally meritorious receives no support from naturalism. There is no culture- free Archimedian standpoint from which to apply a moral lever to the world. If we could liberate ourselves from all cultural prejudices, we would find that morality no longer had any meaning for us.
Of course, as history shows only too well, no holds are barred when one cultural prejudice seeks to sustain itself against another. Sociobiologists are attacked as fascist dinosaurs still peddling the eugenicist filth of the Social Darwinists of Victorian times. In self-defence they have taken to calling themselves behavioural ecologists or evolutionary psychologists. But whatever his name, no modern sociobiologist believes G.E. Moore's claim that evolutionary ethics necessarily maintains that "we ought to move in the direction of evolution simply because it is the direction of evolution". He may think his expertise about the way societies work makes it likely that he know more than others about which reforms are feasible. But his relativism forces him to deny that his opinion on what is optimal is worth more than that of the proverbial man on the Clapham omnibus.
Part of the reason the reaction to sociobiology has been so vitriolic is that it has concentrated its attention in the past largely on biological or genetic evolution, as if we are pieces of robotic wetware like ants. I agree that the human universals which constitute the holy grail for traditional moral philosophers are to be found in our genes, but I think the phenomena that traditionalists discuss are almost entirely determined by social evolution. I do not believe the strategies we use in coordinating with other human beings are hard-wired - rather we learn them as we grow to maturity by imitating the behaviour of those higher in the pecking order.
Ken Binmore is the author of `Game Theory and the Social Contract Vol 2: just playing' (MIT Press, pounds 29.95)