In his book Practical Induction,Elijah Millgram mounts a powerful attack on instrumentalism. In particular, Millgram targets the instrumentalist claim that desires are by themselves reason-giving, that their reason-giving power is not grounded in any other independent fact. According to Millgram, desires, like beliefs, cannot license inferences (desires license inferences to conclusions about what we have reason to do; beliefs license inferences to other belief s and to conclusions about what we have reason to do) if they do not depend for their own justification on some prior mental states. Beliefs depend on prior beliefs and desires on feelings of pleasure and these in turn are grounded respectively in facts about the world and about desirability. If our desires would not depend in this way on other facts it would be possible for us to rationally desire what we want when we want; we could, as he puts it, ‘desire at will.'