Mark Balaguer

This paper develops a novel version of anti-platonism, called semantic fictionalism. The view is a response to the platonist argument that we need to countenance propositions to account for the truth of sentences containing `that'-clause singular terms, e.g., sentences of the form `x believes that p' and `σ means that p'. Briefly, the view is that (a) platonists are right that `that'-clauses purport to refer to propositions, but (b) there are no such things as propositions, and hence, (c) `that'-clause-containing sentences of the above sort are not true-they are useful fictions. Semantic fictionalism is an extension of Hartry Field's mathematical fictionalism, but my defense of the view is not analogous to his. One of the many virtues of my defense is its generality: it explains how we can adopt a fictionalist stance towards all abstract singular terms, e.g., mathematical singular terms and `that'-clauses.

Mathematical fictionalism (or as I'll call it, fictionalism) is best thought of as a reaction to mathematical platonism. Platonism is the view that (a) there exist abstract mathematical objects (i.e., nonspatiotemporal mathematical objects), and (b) our mathematical sentences and theories provide true descriptions of such objects. So, for instance, on the platonist view, the sentence ‘3 is prime’ provides a straightforward description of a certain object—namely, the number 3—in much the same way that the sentence ‘Mars is red’ provides a description of Mars. But whereas Mars is a physical object, the number 3 is (according to platonism) an abstract object. And abstract objects, platonists tell us, are wholly nonphysical, nonmental, nonspatial, nontemporal, and noncausal. Thus, on this view, the number 3 exists independently of us and our thinking, but it does not exist in space or time, it is not a physical or mental object, and it does not enter into causal relations with other objects. This view has been endorsed by Plato, Frege (1884, 1893-1903, 1919), Gödel (1964), and in some of their writings, Russell (1912) and Quine (1948, 1951), not to mention numerous more recent philosophers of mathematics, e.g., Putnam (1971), Parsons (1971), Steiner (1975), Resnik (1997), Shapiro (1997), Hale (1987), Wright (1983), Katz (1998), Zalta (1988), and Colyvan (2001).

This paper argues for a certain kind of anti-metaphysicalism about the temporal ontology debate, i.e., the debate between presentists and eternalists over the existence of past and future objects. Three different kinds of anti-metaphysicalism are defined—namely, non-factualism, physical-empiricism, and trivialism. The paper argues for the disjunction of these three views. It is then argued that trivialism is false, so that either non-factualism or physical-empiricism is true. Finally, the paper ends with a discussion of whether we should endorse non-factualism or physical-empiricism. An initial reason is provided for thinking that non-factualism might be true, but in the end, the paper leaves this question open. The paper also argues against a certain kind of necessitarianism about the temporal ontology debate; but this isn't an extra job—the falsity of this necessitarian view falls out of the other arguments as a sort of corollary.

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