Abstract

It is common sense to say that, at least sometimes, what one has reason to do depends on what one wants. In contemporary ethical theory, "internalists" and "externalists" divide over the issue whether one's practical reasons are always dependent on one's desires. Internalists insist, while externalists deny, that an agent has reason to act only if that agent wants, or could come to want, to so act. ;The present investigation attempts to adjudicate the issue dividing internalists and externalists by assessing the ability of each theory to meet two challenges. The first challenge is to satisfy two general requirements on any theory of reasons. The "internalism requirement" holds that reasons for action must be capable of motivating the agent for whom they are reasons. The "content requirement" holds that a theory of reasons must specify some distinctive and plausible content for claims ascribing reasons to agents. I argue, first, that these are genuine requirements, and that they place substantive constraints on the form a theory of reasons can take. Second, against contemporary and influential arguments to the contrary, I show that internalist views can meet these constraints and that leading externalist views cannot. ;The second challenge is to show how the favored theory of reasons can accommodate familiar facts about practical irrationality. A theory of reasons must have the resources to explain how an agent might fail to be motivated to act in the face of an acknowledged reason. Externalists have argued that internalist theories do not have the resources to explain such motivational failures. I argue that this charge is based on an inadequate conception of desire, one according to which to have a desire is necessarily to be motivated to pursue its object. In response, I develop and argue for a more sophisticated conception of desire. I argue that desires can play various roles within the psychology of the agent, and that only one of their roles is to bring about their own satisfaction. Because a desire's role might not involve motivating an agent to bring about its satisfaction, internalist theories can account for motivational failures