 Most libertarians endorse an event-causal or agent-causal account of sourcehood. Both these accounts maintain that exercises of the power of self-determination consist partly in the agent’s bringing about her choice or action, but they disagree on how to analyze an agent’s bringing about her choice. While event-causal libertarianism admits of different species, at the heart of this view is the idea that self-determining an action requires, at minimum, that the agent cause the action and that an agent’s causing his action is wholly reducible to mental states and other events involving the agent nondeviantly causing his action. Consider an agent’s raising his hand. According to the event-causal model at its most basic level, an agent’s raising his hand consists in the agent’s causing his hand to rise and his causing his hand to rise consists in apt mental states and events involving the agent—such as the agent’s desire to ask a question and his belief that he can ask a question by raising his hand—nondeviantly causing his hand to rise. (The nondeviance clause is required since it seems possible that an event be brought about by one’s desires and beliefs and yet not be self-determined, or even an action for that matter, due to the unusual causal path leading from the desires and beliefs to action. Imagine a would-be accomplice of an assassin believes that his dropping his cigarette is the signal for the assassin to shoot his intended victim and he desires to drop his cigarette and yet this belief and desire so unnerve him that he accidentally drops his cigarette. While the event of dropping the cigarette is caused by a relevant desire and belief it does not seem to be self-determined and perhaps is not even an action [cf. Davidson 1973].) To fully spell out this account, event-causal libertarians must specify which mental states and events are apt (cf. Brand 1979)—which mental states and events are the springs of self-determined actions—and what nondeviance consists in (cf. Bishop 1989). (We note that this has proven very difficult, enough so that some take the problem to spell doom for event-causal theories of action. Such philosophers [e.g., Taylor 1966 and Sehon 2005] take agential power to be conceptually and/or ontologically primitive and understand reasons explanations of action in irreducibly teleological terms. See Stout 2010 for a brisk survey of discussions of this topic.) For ease, in what follows we will assume that apt mental states are an agent’s reasons that favor the action.