Frege's puzzle is this. Lois Lane believes, it seems, that Superman is strong. And Clark Kent is, of course, Superman. So it seems to follow that Lois Lane believes that Clark Kent is strong. But Lois would deny that Clark Kent is strong, and it seems wrong to say that she believes it. So what's going on?Eric suggests the problem is that "Almost all the participants in this literature seem to take for granted something that I reject: that sentences ascribing beliefs must be determinately true or false, at least once those sentences are disambiguated or contextualized in the right way".
I have discussed this problem before, notably here, in the context of impersonal verbs taking that-clauses. The problem is that whatever applies to belief-ascriptions, must apply also to impersonal ascriptions such as "there is evidence that p", "it was discovered that p in yyyy", "according to the theory of X, it is the case that p", for these sentences, as will become clear, also suffer from the substitution problem. Thus, if Eric is right, sentences like "there is little evidence that Edward de Vere was the author of Macbeth" are not determinately true or false, which seems counterintuitive.
Let me explain. I often warn people against unquestioning acceptance of Wikipedia, but what it says here today seems unquestionably right.
"The Oxfordian theory of Shakespearean authorship proposes that Edward de Vere, 17th Earl of Oxford (1550–1604), wrote the plays and poems traditionally attributed to William Shakespeare of Stratford-upon-Avon.That is surely true. That is what the Oxfordian theory is. Whether the theory is right or not is irrelevant. The question is whether this characterisation of the theory is correct. It is, and it uses, without mentioning, the proper names 'Edward de Vere' and 'Shakespeare'. But there are circumstances in which its truth would not survive substitution. Let's suppose we discover that Francis Bacon were identical with Shakespeare, as Cantor famously believed, spending much of his personal fortune trying to prove it. If so, we should be able to substitute 'Francis Bacon' for 'William Shakespeare' in a sentence telling us what the Oxfordian theory is. But it is not true that, according to the Oxfordian theory, Edward de Vere was Francis Bacon. Nor would be true to say that plays and poems such as 'Macbeth' were traditionally attributed to Francis Bacon, even if Shakespeare were Bacon. Nor would it be true to say that we discovered that Shakespeare was Shakespeare in 2012, even if it were true that we discovered that Shakespeare was Bacon in 2012.
Yet sentences like "Oxfordians believe that Edward de Vere wrote the plays and poems traditionally attributed to William Shakespeare" are unquestionably true, i.e. determinately true (or false). By equal reasoning, since the problem seems identical, this suggests that sentences ascribing beliefs must be determinately true or false.