Abstract
The paper argues that it is possible for an incompatibilist to accept John Martin Fischer's plausible insistence that the question whether we are morally responsible agents ought not to depend on whether the laws of physics turn out to be deterministic or merely probabilistic. The incompatibilist should do so by rejecting the fundamentalism which entails that the question whether determinism is true is a question merely about the nature of the basic physical laws. It is argued that this is a better option for ensuring the irrelevance of physics than the embrace of semi-compatibilism, since there are reasons for supposing that alternate possibilities are necessary for moral responsibility, despite Fischer's claims to the contrary. There are two distinct reasons for supposing that alternate possibilities might be necessary for moral responsibility—one of which is to do with fairness, the other to do with agency itself. It is suggested that if one focuses on the second of these reasons, Fischer's arguments for supposing that alternate possibilities are unnecessary for moral responsibility can be met by the incompatibilist. Some possible reasons for denying that alternate possibilities are necessary for the existence of agency are then raised and rejected.