Two Senses of "Why": Traits and Reasons in the Explanation of Action

I discuss the respective roles of traits and reasons in the explanation of action. I begin by noting that traits and reasons explanations are systematically connected: traits explanations require motivation by reasons. Actions due to psychiatric conditions such as mental disorders cannot be explained by an appeal to traits. Because traits require motivation by reasons, it is often possible to explain one and the same action by an appeal to either the agent's traits or to her reasons. I then ask whether it follows from here that traits and reasons explanations of action are equivalent – though perhaps offered from different points of view – or whether they differ in interesting ways. I argue that the differences are interesting and important – traits and reasons explanations answer different “why” questions regarding action: a reasons explanation tells us what reasons motivated the agent acting; a traits explanation, by contrast, indicates something about an agent’s reasons but tells us something else in addition: it tells us why the agent acted on those as opposed to other available reasons.