Alas, ecumenicism has to stop somewhere. The fifth (and final thesis) of my version of RTM does depart from the standard Frege architecture.
Fifth Thesis: Whatever distinguishes coextensive concepts is ipso facto ‘in the head’. This means, something like that
it’s available to be a proximal cause (/effect) of mental processes.10
As I understand it, the Fregean story makes the following three claims about modes of presentation:
I take it that one of the things that distinguishes Fregeans sans phrase from neo -Fregeans (like e.g. Peacocke 1992) is that the latter are not committed to Fege’s anti-mentalism and are therefore free to agree with Thesis Five if they’re so inclined. Accordingly, for the neo -sort of Fregean, the sermon that follows will seem to be preached to the converted.
5.2 Since MOPs can distinguish concepts, they explain how it is possible to entertain one, but not the other, of twocoreferential concepts; e.g. how it is possible have the concept WATER but not the concept H2O, hence how itis possible to have (de dicto) beliefs about water but no (de dicto) beliefs about H2O.
5.3 MOPs are abstract objects; hence they are non-mental.
In effect, I’ve signed on for 5.2; it’s the claim about MOPs that everybody must accept who has any sympathy at all for the Frege programme. But I think there are good reasons to believe that 5.2 excludes both 5.1 and 5.3. In which case, Itake it that 5.1 and 5.3 will have to go.
—’What’s wrong with 5.1: 5.1 makes trouble for 5.2: it’s unclear that you can hold onto 5.2 if you insist, as Frege does, that MOPs be identified with senses. One thing (maybe the only one) that we know for sure about senses is thatsynonyms share them. So if MOPs are senses and distinct but coextensive concepts are distinguished (solely) by theirMOPs, then synonymous concepts must be identical, and it must not be possible to think either without thinking theother. (This is the so-called ‘substitution test’ for distinguishing modes of presentation.) But (here I follow Mates1962), it is possible for Fred to wonder whether John understands that bachelors are unmarried men even though Fred does notwonder whether John understands that unmarried men are unmarried men. The moral seems to be that if 5.2 is right, so thatMOPs just are whatever it is that the substitution test tests for, then it’s unlikely that MOPs are senses.
Here’s a similar argument to much the same conclusion. Suppose I tell you that Jackson was a painter and that Pollock was a painter, and I tell you nothing else about Jackson or Pollock. Suppose, also, that you believe what I tell you. Itlooks like that fixes the senses of the names ‘Jackson’ and ‘Pollock’ if anything could; and it looks like it fixes them asboth having the same sense: viz. a painter. (Mutatis mutandis, it looks as though I have fixed the same inferential role forboth.) Yet, in the circumstances imagined, it’s perfectly OK—perfectly conceptually coherent—for you to wonderwhether Jackson and Pollock were the same painter. (Contrast the peculiarity of your wondering, in such a case, whetherJackson was Jackson or whether Pollock was Pollock.) So, then, by Frege’s own test, JACKSON and POLLOCKcount as different MOPs. But if concepts with the same sense can be different MOPs then, patently, MOPs can’t besenses. This isn’t particularly about names, by the way. If I tell you that a flang is a sort of machine part and a glanf is asort of machine part, it‘s perfectly OK for you to wonder whether a glanf is a flang.11
You can’t, of course, do this trick with definite descriptions since they presuppose uniqueness of reference. If you mean by “Jackson” the horse that bit John, and you mean by “Pollock” the horse that bit John, you can’t coherently wonder whether Jackson is the same horse as Pollock.By the way, I have the damnedest sense of déjà vu about theargument in the text; I simply can’t remember whether I read it somewhere or made it up.Jean-marc pizano