The Transparency of Mental Content

As the surrounding discussion makes clear, Dummett's claim isn't merely the fairly weak thesis that, for any two expressions in a person's repertoire, it must be possible for that person to come to know whether or not they mean the same. Rather, the claim is that it must be possible for that person to come to know such a fact purely introspectively, without the benefit of further empirical investigation--a priori, as I shall also occasionally put it. Dummett doesn't say much about the basis for his conviction that 'transparency' in this sense-epistemic transparency as I shall sometimes call it, to distinguish it from the referential variety -is undeniable feature of the notion of meaning. He gives the impression of finding the claim too obvious to need arguing. In this respect, I believe, he follows in the footsteps of Frege and Russell, both of whom gave epistemic transparency a pivotal, if unargued, role in their respective theories of linguistic and mental content. In another paper, I hope to discuss this historical point. In this paper, however, my concern will be purely philosophical and, then, only with mental content. I believe that the notion of epistemic transparency does play an important role in our ordinary conception of mental content and I want to say what that role is. Unfortunately, the task is a large one; here I am able only to begin on its outline. I shall proceed somewhat indirectly, beginning with a discussion of