Boghossian raises an interesting question. Can we think of a person who has desires but no beliefs? His answer is contained in this curious passage from Content and Justification:
It's hard to imagine. The reason is that we think that someone can want p at some time t only if he either believes it to be not p at t or is unsure whether it is p at t. You cannot want p at a given time, if at that time you already believe that p has occurred. You can be glad ... but you cannot want it to occur (105).
If you're unsure as to whether p, it doesn't follow that you believe p or its negation. It does follow that either you believe p or are unsure as to whether p. So, even if that disjunctive condition obtains whenever someone desires, I don't see how this shows that if you imagine someone who desires something you thereby imagine someone who believes something. The reason this matters is that Boghossian thinks that he can establish the normativity of content by establishing that belief is normative (in the sense that belief ascriptions commit you to certain ought judgments) and establishing that we understand the notion of content only by understanding the notion of belief. There are questions we can raise at each step, but this seems like a very simple and superficial mistake that he's made. It could be that I'm missing something obvious.