Moral relativism and slavery

Many contemporary philosophers and social scientists consider values and conceptions of justice to be at base irrational. We may hope to explain these conceptions in their context or explore the internal consistency of a given choice of values, but such conceptions vary historically in a fashion beyond the reach of any objective assessment. Metaethical relativism seems to follow from these claims; values are simply relative to the conventions or experiences of the societies, groups, classes, or persons who hold them. At most, these views maintain, we may achieve a kind of sociological or anthropological – reductionist – objectivity about morals: We may show how particular values serve certain social or class interests. But no ethical conception – no idea about a good life for humans – may claim objectivity on its own terms.

Some judgments about justice and equality, however, seem more secure to most of us. Slavery, for example, and Nazi genocide are monstrous. They are abhorrent not merely as a matter of opinion – the Nazis still have many defenders and slavery once did – but because of their wanton murderousness and cruelty, their waste of lives, let alone of human potential for a good life.