  Quine explicitly acknowledges that we could not in practice manage without idioms of propositional attitude, and that most uses of such idioms are entirely unobjectionable. But such idioms allow the formation of sentences which do not correspond to facts of the matter. For that reason, Quine excludes them from regimented theory; they are not be used when we are concerned with “limning the true and ultimate structure of reality” (1960, 221). (Some philosophers might insist: ‘Either you accept the concept of belief or you don’t’. Quine would not agree; see 1986e for closely related remarks about the idea of knowing who someone is.)