If he is to assert (5) as well as (1)–(4), Quine must give a sense to the distinction between “matter of fact” and “convention” which has no links with the usual instrumentalist-phenomenalist distinction—that between what we are really acquainted with and what we “posit” to cope with stimuli. The only way he can do so, as far as I can see, is simply to pick out the elementary particles of contemporary physics as paradigmatically matter-of-factual and explain that the sense in which there is no matter of fact about meanings or beliefs is that different things can be said about what a sentence
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