David Liggins

A pretence theory of a discourse is one which claims that we do not believe or assert the propositions expressed by the sentences we utter when taking part in the discourse: instead, we are speaking from within a pretence. Jason Stanley argues that if a pretence account of a discourse is correct, people with autism should be incapable of successful participation in it; but since people with autism are capable of participiating successfully in the discourses which pretence theorists aim to account for, all these accounts should be rejected. I discuss how pretence theorists can respond, and apply this discussion to two pretence theories, Stephen Yablo's account of arithmetic and Kendall Walton's account of negative existentials. I show how Yablo and Walton can escape Stanley's objection

Platonism in the philosophy of mathematics is the doctrine that there are mathematical objects such as numbers. John Burgess and Gideon Rosen have argued that that there is no good epistemological argument against platonism. They propose a dilemma, claiming that epistemological arguments against platonism either rely on a dubious epistemology, or resemble a dubious sceptical argument concerning perceptual knowledge. Against Burgess and Rosen, I show that an epistemological anti- platonist argument proposed by Hartry Field avoids both horns of their dilemma.

In the ‘ordinary business of life’, everyone makes claims about what there is. For instance, we say things like: ‘There are some beautiful chairs in my favourite furniture shop’. Within the context of philosophical debate, some philosophers also make claims about what there is. For instance, some ontologists claim that there are chairs; other ontologists claim that there are no chairs. What is the relation between ontologists’ philosophical claims about what there is and ordinary claims about what there is? According to Cian Dorr, ontologists’ claims and denials of existence belong to ‘a sort of professional jargon’. Dorr claims, for example, that ‘There are prime numbers between 20 and 30’ can be used superficially or used fundamentally. Ordinary uses of are superficial: we use the sentence to assert a boring, well-known truth. But in the ontology room, is used fundamentally, to assert that numbers are ‘part of the ultimate furniture of reality’: and this is a substantial metaphysical doctrine, not a boring truth. In this paper, we will show that none of Dorr’s arguments for these claims succeeds.

Much recent discussion in the philosophy of mathematics has concerned the indispensability argument—an argument which aims to establish the existence of abstract mathematical objects through appealing to the role that mathematics plays in empirical science. The indispensability argument is standardly attributed to W. V. Quine and Hilary Putnam. In this paper, I show that this attribution is mistaken. Quine's argument for the existence of abstract mathematical objects differs from the argument which many philosophers of mathematics ascribe to him. Contrary to appearances, Putnam did not argue for the existence of abstract mathematical objects at all. I close by suggesting that attention to Quine and Putnam's writings reveals some neglected arguments for platonism which may be superior to the indispensability argument.

Many philosophers posit abstract entities – where something is abstract if it is acausal and lacks spatio-temporal location. Theories, types, characteristics, meanings, values and responsibilities are all good candidates for abstractness. Such things raise an epistemological puzzle: if they are abstract, then how can we have any epistemic access to how they are? If they are invisible, intangible and never make anything happen, then how can we ever discover anything about them? In this article, I critically examine epistemological objections to belief in abstract objects offered by Paul Benacerraf, Colin Cheyne and Hartry Field.