SUPERVENIENCE AND MORAL REALISM

Simon Blackburn has developed an interesting challenge to moral realism based on its alleged inability to account for supervenience relations between the moral and nonmoral. If supervenience holds, then any base property once giving rise to a supervening one must always do so. The realist accepts supervenience, but also (according to Blackburn) accepts the claim that nonmoral base properties do not necessitate the moral ones that supervene on them. This combination is thought deadly, because it leaves the realist without an explanation of why ethical supervenience should be true. I offer three responses on behalf of the moral realist. The first rejects the need for explanation, arguing that supervenience should be understood as closely analogous to Leibniz's law, which, I argue, needs no defense. I next argue that ethical naturalism may be right, and if so, would provide an adequate response to Blackburn. Lastly, I show that the success of Blackburn's arguments implies a global antirealism, and so does not, as he claims, amount to a special problem for realism in ethics.