INTRODUCTION

According to one popular version of the dispositional theory of value, the version I favour, there is an analytic connection between the desirability of an agent's acting in a certain way in certain circumstances and her having a desire to act in that way in those circumstances if she were fully rational (Rawls 1971: Chapter 7; Brandt 1979: Chapter 1; Smith 1989, 1992, 1994). If claims about what we have reason to do are equivalent to, or are in some way entailed by, claims about what it is desirable for us to do – if our reasons follow in the wake of our values – then it follows that there is a plausible analytic connection between what we have reason to do in certain circumstances and what we would desire to do in those circumstances if we were fully rational.

The idea that there is such an analytic connection will hardly come as news. It amounts to no more and no less than an endorsement of the claim that all reasons are “internal,” as opposed to “external,” to use Bernard Williams's terms (Williams 1980). Or, to put things in the way Christine Korsgaard favours, it amounts to an endorsement of the “internalism requirement” on reasons (Korsgaard 1986). But how exactly is the internalism requirement to be understood? What does it tell us about the nature of reasons? And wherein lies its appeal? My aim in this paper is to answer these questions.

The paper divides into three main sections.