The necessity of alternate possibilities for moral responsibility

Harry Frankfurt has famously criticized the principle of alternate possibilities—the principle that an agent is morally responsible for performing some action only if able to have done otherwise than to perform it—on the grounds that it is possible for an agent to be morally responsible for performing an action that is inevitable for the agent when the reasons for which the agent lacks alternate possibilities are not the reasons for which the agent has acted. I argue that an incompatibilist about determinism and moral responsibility can safely ignore so-called “Frakfurt-style cases ” and continue to argue for incompatibilism on the grounds that determinism rules out the ability to do otherwise. My argument relies on a simple—indeed, simplistic—weakening of the principle of alternate possibilities that is explicitly designed to be immune to Frankfurt -style criticism. This alternative to the principle of alternate possibilities is so simplistic that it will no doubt strike many readers as philosophically fallow. I argue that it is not. I argue that the addition of one highly plausible premise allows for the modified principle to be employed in an argument for incompatibilism that begins with the observation that determinism rules out the ability to do otherwise. On the merits of this argument I conclude that deterministic moral responsibility is impossible and that Frankfurt ’s criticism of the principle of alternate possibilities—even if successful to that end—may be safely ignored