The Consequence Argument is a staple in the defense of libertarianism, the view that free will is incompatible with determinism and that humans have free will. It is often thought that libertarianism is consistent with a certain naturalistic view of the world — that is, that libertarian free will can be had without metaphysical commitments beyond those pro- vided by our best (indeterministic) physics. In this paper, I argue that libertarians who endorse the Consequence Argument are forced to reject this (...) naturalistic worldview, since the Consequence Argument has a sis- ter argument — I call it the Supervenience Argument — which cannot be rejected without threatening either the Consequence Argument or the naturalistic worldview in question. (shrink)