I will now take it that Adams and Aizawa ought to concede that there is no difference in content between my thought that ‘the harbour Bridge looks beautiful in the sunlight this morning’ and my utterance to you that ‘the Harbour Bridge looks beautiful in the sunlight this morning.’ Indeed I might think that very sentence to myself in my head before uttering it to you. If Adams and Aizawa are happy to accept this conclusion, then we really have no disagreement, because we have an example of thinking in natural language (English in this instance). Similarly it seems obvious to me that a Venn diagram that I am imagining now has the same meaning as the Venn diagram that I am drawing on the page now.
Yes, A&A agree that there is no difference in content as outlined in the first sentence here. We note this here:
The first thing to observe about the derived/non-derived distinction is that it concerns the conditions in virtue of which an object bears a particular content. A thought might bear the content that the cat is hungry in virtue of satisfying some conditions on non-derived content, whereas a particular inscription on a piece of paper might bear that same content by satisfying some other conditions on derived content.Menary thinks this concession, however, cooks our goose. He observes that the first thought is an instance of thinking in English and that we have mental imagery. And, of course, there is thinking in English and there is mental imagery.
But, this apparently depends on a particular interpretation of "thinking in English" and there being mental imagery. To a first approximation, this only shows that there are instances of derived representations occurring in thought if there is a token of an English sentence in the head or a picture in the head, rather than merely a mentalese representation of an English sentence in the head or a mentalese representation of an image. It looks as though this is a problem for A&A only if thinking in English and mental imagery are cases of non-derived representations occurring in thought. But, Menary gives no reason to think this. He takes it as obvious. But, of course, there is a vast literature on these issues, a literature that A&A think does not bode well for Menary.