Abstract

I defend the view that supervenience relations need not be explained. My view is that some supervenience relations are brute, and explanatorily ultimate. I examine an argument of Terrence Horgan and Mark Timmons. They aim to rehabilitate John Mackie’s metaphysical queerness argument. But the explanations of supervenience that Horgan and Timmons demand are semantic explanations. I criticize their attempt to explain psychophysical supervenience in this fashion. I then turn to their ‘Twin Earth’ argument against naturalist moral realism. I reconstruct their argument in a charitable spirit. But then I show that the argument mutates into an epistemological argument. That is where the real problems for moral realism lie