Full Idea
It's not clear what the point would be of an explanation of the intentionality of attitudes which presupposes objects that are intentional intrinsically. Why not just say that the attitudes are?
Gist of Idea
We can't use propositions to explain intentional attitudes, because they would need explaining
Source
Jerry A. Fodor (Psychosemantics [1987], Ch.3)
Book Reference
Fodor,Jerry A.: 'Psychosemantics' [MIT 1993], p.80