A Metaphysics for Freedom argues that agency itself-and not merely the special, distinctively human variety of it-is incompatible with determinism. For determinism is threatened just as surely by the existence of powers which can be unproblematically accorded to many sorts of animals, as by the distinctively human powers on which the free will debate has tended to focus. Helen Steward suggests that a tendency to approach the question of free will solely through the issue of moral responsibility has obscured the fact that there is a quite different route to incompatibilism, based on the idea...