Abstract

I begin by outlining a general theory of reasons, on which a purported reason R is a reason to F just in case it makes sense to F on the basis of R. The dissertation is then devoted to specifying the conditions under which it makes sense to act on some given basis. There are two main questions. ;The first is how an action must be related to an end for it to make sense to do the action toward that end. One prevalent view is that the action should be sufficient for the end. Another is that the action should be necessary. After criticizing both of these suggestions, I offer a new account, according to which the end must be a difference the action will or may make. ;The second question is what more is required for there to be a reason, over and above the action's being properly related to its end. Not every difference an action makes corresponds to a reason. For instance, tooth brushing reduces cavities, but also wears down the bristles. The former is a reason for brushing, the latter not. Clearly there is more to there being a reason than there being a difference the action makes. What is it? One popular answer is that the reasons are the ends you presently want. I provide and defend an alternative answer, on which the fact that you want the end plays an essential part in the explanation of the action, but is not part of what makes the end a reason. ;Defending this answer requires refuting a number of objections. The chief among them is that, as all practical reasoning starts from something wanted, the existence of a reason must require the presence in the agent of a desire suitable as a starting point for reasoning to the action. I explain why the most common reply is unsatisfactory, and offer what I take to be a better one. ;In the final chapter I give a positive account of the notion of a reason for action, using the notion of a step to explain how practical and theoretical reasons are instances of a single type