Full Idea
According to Gricean theories of meaning, the meaning of a sentence is inherited from the propositional attitudes that the sentence is conventionally used to express.
Gist of Idea
Grice thinks meaning is inherited from the propositional attitudes which sentences express
Source
Jerry A. Fodor (Psychosemantics [1987], p. 50)
Book Reference
Fodor,Jerry A.: 'Psychosemantics' [MIT 1993], p.50
A Reaction
Since the propositional attitudes contain propositions, this seems like a very plausible idea. If an indexical like 'I' is involved, the meaning of the sentence is not the same as its 'conventional' use.