 The quoted sentences that appear in (A) and (B) are singular terms; e.g., “‘The cat is on the mat’” refers to the sentence ‘The cat is on the mat’, and (A) says of this sentence that it has a certain property, namely, that of being a well-formed English sentence. Thus, if sentences like (A) are true — and it certainly seems that they are — then they commit us to believing in the existence of sentences. Now, one might hold a physicalistic view here according to which linguistics is about actual (external) sentence tokens, e.g., piles of ink and verbal sound waves. (This view was popular in the early part of the 20th century — see, e.g., Bloomfield (1933), Harris (1954), and Quine (1953).) Or alternatively, one might hold a conceptualistic view, maintaining that linguistics is essentially a branch of psychology; the main proponent of this view is Noam Chomsky (1965, chapter 1), who thinks of a grammar for a natural language as being about an ideal speaker-hearer's knowledge of the given language, but see also Sapir (1921), Stich (1972), and Fodor (1981). But there are reasons for thinking that neither the physicalist nor the conceptualist approach is tenable and that the only plausible way to interpret linguistic theory is as being about sentence types, which of course, are abstract objects (proponents of the platonistic view include Katz (1981), Soames (1985), and Langendoen and Postal (1985)). Katz constructs arguments here that are very similar to the ones we considered above, in connection with mathematical objects  (section 4.1).  One argument here is that linguistic theory seems to have consequences that are (a) true and (b) about sentences that have never been tokened (internally or externally), e.g., sentences like ‘Green Elvises slithered unwittingly toward Arizona's favorite toaster’. (Of course, now that I've written this sentence down, it has been tokened, but it seems likely that before I wrote it down, it had never been tokened.) Standard linguistic theory entails that many sentences that have never been tokened (internally or externally) are well-formed English sentences. Thus, if we want to claim that our linguistic theories are true, then we have to accept these consequences, or theorems, of linguistic theory. But these theorems are clearly not true of any sentence tokens (because the sentences in question have never been tokened) and so, it is argued, they must be true of sentence types.