The problematic features of Quine's set theories NF and ML are a result of his replacing the higher-order predicate logic of type theory by a first-order logic of membership, and can be resolved by returning to a second-order logic of predication with nominalized predicates as abstract singular terms. We adopt a modified Fregean position called conceptual realism in which the concepts (unsaturated cognitive structures) that predicates stand for are distinguished from the extensions (or intensions) that their nominalizations denote as singular (...) terms. We argue against Quine's view that predicate quantifiers can be given a referential interpretation only if the entities predicates stand for on such an interpretation are the same as the classes (assuming extensionality) that nominalized predicates denote as singular terms. Quine's alternative of giving predicate quantifiers only a substitutional interpretation is compared with a constructive version of conceptual realism, which with a logic of nominalized predicates is compared with Quine's description of conceptualism as a ramified theory of classes. We argue against Quine's implicit assumption that conceptualism cannot account for impredicative concept-formation and compare holistic conceptual realism with Quine's class Platonism. (shrink)

There is a long tradition comparing moral knowledge to mathematical knowledge. In this paper, I discuss apparent similarities and differences between knowledge in the two areas, realistically conceived. I argue that many of these are only apparent, while others are less philosophically significant than might be thought. The picture that emerges is surprising. There are definitely differences between epistemological arguments in the two areas. However, these differences, if anything, increase the plausibility of moral realism as compared to mathematical realism. It (...) is hard to see how one might argue, on epistemological grounds, for moral antirealism while maintaining commitment to mathematical realism. But it may be possible to do the opposite. (shrink)

This paper argues that it is scientific realists who should be most concerned about the issue of Platonism and anti-Platonism in mathematics. If one is merely interested in accounting for the practice of pure mathematics, it is unlikely that a story about the ontology of mathematical theories will be essential to such an account. The question of mathematical ontology comes to the fore, however, once one considers our scientific theories. Given that those theories include amongst their laws assertions that imply (...) the existence of mathematical objects, scientific realism, when construed as a claim about the truth or approximate truth of our scientific theories, implies mathematical Platonism. However, a standard argument for scientific realism, the 'no miracles' argument, falls short of establishing mathematical Platonism. As a result, this argument cannot establish scientific realism as it is usually defined, but only some weaker position. Scientific 'realists' should therefore either redefine their position as a claim about the existence of unobservable physical objects, or alternatively look for an argument for their position that does establish mathematical Platonism. (shrink)

The difference between Carnap and Quine over analyticity is usually thought to turn on a disagreement as to whether there is a notion of meaning, or rules of language, which enable us to define that idea. This paper argues that the more important disagreement is epistemological. Quine came to accept a notion of analyticity. That leaves him in a position somewhat like Putnam's in ‘The Analytic and the Synthetic’: that there is a notion of analyticity, but that it is of (...) no philosophical importance. But their reasons for thinking analyticity unimportant are quite different: for Putnam it is because all analytic truths are trivial; for Quine, the notion of analyticity itself is unimportant. I contrast Putnam's position with that of Carnap, and also contrast Carnap and Quine. Analyticity only has the force that it has for Carnap because he accepts the Principle of Tolerance, the idea that changes within a language and changes of language are subject to justification in different senses. Quine rejects that idea. That is why he does not take analyticity to be philosophically important or useful. (shrink)

Russell's notion of an incomplete symbol has become a standard against which philosophers compare their views on the relationship between language and the world. But Russell's exact characterization of incomplete symbols and the role they play in his philosophy are still disputed. In this paper, I trace the development of the notion of an incomplete symbol in Russell's philosophy. I suggest – against Kaplan, Evans, and others – that Russell's many characterizations of the notion of an incomplete symbol are compatible. (...) To this end, I examine and reject arguments for the purported incompatibility between declaring an expression to be incomplete and incorporating that symbol into a compositional semantic theory. I then examine how Russell puts the notion of an incomplete symbol to use in metaphysics. (shrink)

Spontaneously, one might want to object that it is essential to ordered pairs that they can contain the same members and yet be different: ≠. Hence, it may be argued, no set-theoretical substitute can fully capture the sense in which ordered pairs are ordered. Quine, however, rejects all such talk of essences and senses. As I will show, this anti-essentialist attitude is intimately related to his view of the ontological import of explication procedures. According to Quine, an explication should help (...) us reform our established theory of the world so that the resulting scheme assumes an ontology that is as sparse as possible. Allegedly, what Wiener and Kuratowski show is simply that whatever good is accomplished by talking of ordered pairs can be accomplished by talking of sets. And, Quine adds, ‘[a] similar view can be taken of every case of explication: explication is elimination’. (shrink)

This Companion to the philosophy of science reflects fairly well the gloomy state of affairs in this subfield at its best—concerns, problems, prejudices, and all. The field is still stuck with the problem of justification of science, refusing to admit that there is neither need nor possibility to justify science and forbid dissent from it.

The Polish logicians' propositional calculi, which consist in a distinct synthesis of the Fregean and Boolean approaches to logic, influenced W. V. Quine's early work in formal logic. This early formal work of Quine's, in turn, can be shown to serve as one of the sources of his holistic conception of natural language.

The paper is concerned with Quine's substitutional account of logical truth. The critique of Quine's definition tends to focus on miscellaneous odds and ends, such as problems with identity. However, in an appendix to his influential article On Second Order Logic, George Boolos offered an ingenious argument that seems to diminish Quine's account of logical truth on a deeper level. In the article he shows that Quine's substitutional account of logical truth cannot be generalized properly to the general concept of (...) logical consequence. The purpose of this paper is threefold: first, to introduce the reader to the metamathematics of Quine's substitutional definition of logical truth; second, to make Boolos' result accessible to a broader audience by giving a detailed and self-contained presentation of his proof; and, finally, to discuss some of the possible implications and how a defender of the Quinean concepts might react to the challenge posed by Boolos' result. (shrink)

Henry M. Sheffer is well known to logicians for the discovery (or rather, the rediscovery) of the ?Sheffer stroke? of propositional logic. But what else did Sheffer contribute to logic? He published very little, though he is known to have been carrying on a rather mysterious research program in logic; the only substantial result of this research was the unpublished monograph The General Theory of Notational Relativity. The main aim of this paper is to explain, as far as possible (given (...) the scanty evidence), the nature of Sheffer's program, and the reasons for its failure. The paper concludes with a discussion of Sheffer's only true logical descendant, C.H. Langford, and his contributions to model theory. (shrink)

In rounded terms and modem dress a theory of intentionality is a theory about how humans take in information via the senses and in the very process of taking it in understand it and, most often, make subsequent use of it in guiding human behaviour. The problem of intentionality in this century has been the problem of providing an adequate explanation of how a purely physical causal system, the brain, can both receive information and at the same time understand it, (...) that is, to put it even more briefly, how a brain can have semantic content. In these two articles, one in this issue of the journal and one in the next, I engage in a critical examination of the two most thoroughly canvassed approaches to the theory and problem of intentionality in philosophical psychology over the last hundred years. In the first article, entitled 'The modern reduction of intentionality, ' I examine the approach pioneered by Carnap and reaching its apotheosis in the work of Daniel Dennett. In the second article, entitled 'The return to representation, 'I examine the approach which can be traced back to the work of Noam Chomsky but which has been given its canonical treatment in the work of Jerry Fodor. (shrink)