Online research in philosophy

With his customary incisiveness, W. V. Quine presents logic as the product of two factors, truth and grammar--but argues against the doctrine that the logical ...

This paper traces the development of Quine's ontological ideas throughout his early logical work in the period before 1948. It shows that his ontological criterion critically depends on this work in logic. The use of quantifiers as logical primitives and the introduction of general variables in 1936, the search for adequate comprehension axioms, and problems with proper classes, all forced Quine to consider ontological questions. I also show that Quine's rejection of intensional entities goes back to his generalisation of Principia Mathematica in 1932.

W. V. O. Quine's well-known attack upon the analytic-synthetic distinction is held to affect only one of the two species of analytic statements he distinguishes. In particular it is not directed at and does not affect the so-called logical truths. In this paper the scope of Quine's attack is extended so as to embrace the logical truths as well. It is shown that the unclarifiability of the notion of 'synonymy' deprives us not only of "analytic statements that are obtainable from logical truths by the replacement of synonyms with synonyms" but of "logical truths" themselves.

Quine argues that if sentences that are set theoretically equiv- alent are interchangeable salva veritate, then all transparent operators are truth-functional. Criticisms of this argument fail to take into account the conditional character of the conclusion. Quine also argues that, for any person P with minimal logical acuity, if ‘belief’ has a sense in which it is a transparent operator, then, in that sense of the word, P believes everything if P believes anything. The suggestion is made that he intends that result to show us that ‘believes’ has no transparent sense. Criticisms of this argument are either based on unwarranted assertions or on definitions of key terms that depart from Quine’s usage of those terms.

W. V. Quine has made statements about truth which are not obviously compatible, and his statements have been interpreted in more than one way. For example, Donald Davidson claims that Quine has an epistemic theory of truth, but Quine himself often says that truth is just disquotational. This paper argues that Quine should recognize two different notions of truth. One of these is disquotational, the other is empiricist. There is nothing wrong with recognizing two different notions of truth. Both may be perfectly legitimate, even though, to some extent, they may be applicable in different contexts. Roughly speaking, a sentence is true in the empiricist sense if it belongs to a theory which entails all observation sentences which would be assented to by the speakers of the language in question (and no observation sentences which would be dissented from by these speakers). Various objections to this idea are discussed and rejected.

W. V. Quine has made statements about truth which are not obviously compatible, and his statements have been interpreted in more than one way. For example, Donald Davidson claims that Quine has an epistemic theory of truth, but Quine himself often says that truth is just disquotational. This paper argues that Quine should recognize two different notions of truth. One of these is disquotational, the other is empiricist. There is nothing wrong with recognizing two different notions of truth. Both may be perfectly legitimate, even though, to some extent, they may be applicable in different contexts. Roughly speaking, a sentence is true in the empiricist sense if it belongs to a theory which entails all observation sentences which would be assented to by the speakers of the language in question (and no observation sentences which would be dissented from by these speakers). Various objections to this idea are discussed and rejected.

According to the standard story (a) W. V. Quine’s criticisms of the idea that logic is true by convention are directed against, and completely undermine, Rudolf Carnap’s idea that the logical truths of a language L are the sentences of L that are true-in- L solely in virtue of the linguistic conventions for L , and (b) Quine himself had no interest in or use for any notion of truth by convention. This paper argues that (a) and (b) are both false. Carnap did not endorse any truth-by-convention theses that are undermined by Quine’s technical observations. Quine knew this. Quine’s criticisms of the thesis that logic is true by convention are not directed against a truth-by-convention thesis that Carnap actually held, but are part of Quine’s own project of articulating the consequences of his scientific naturalism. Quine found that logic is not true by convention in any naturalistically acceptable sense. But he also observed that in set theory and other highly abstract parts of science we sometimes deliberately adopt postulates with no justification other than that they are elegant and convenient. For Quine such postulations constitute a naturalistically acceptable and fallible sort of truth by convention. It is only when an act of adopting a postulate is not indispensible to natural science that Quine sees it as affording truth by convention ‘unalloyed’. A naturalist who accepts Quine’s notion of truth by convention is therefore not limited (as naturalists are often thought to be) to accepting only those postulates that she regards as indispensible to natural science.

Two questions are raised about Quine's view of truth. He has recently said that ontology is relative to a translation manual: is this the same as relativizing it to a language? The same question may be asked about truth. Should we think there is one concept of truth which is relative to a language, or is there a separate concept for each language (or speaker)? The second question concerns Quine's repeated endorsements of the ?disquotational? account of truth. Does he think this account limits a truth predicate to application to a single language, or can translation (or Tarski's methods) allow us to apply a truth predicate in one language to sentences in other languages? If the latter, can Quine still contend that the disquotational account is a ?full? account of the concept of truth? The answer would tell us whether Quine can be counted among those who would deflate the concept of truth.

I consider the well-known criticism of Quine's characterization of first-order logical truth that it expands the class of logical truths beyond what is sanctioned by the model-theoretic account. Briefly, I argue that at best the criticism is shallow and can be answered with slight alterations in Quine's account. At worse the criticism is defective because, in part, it is based on a misrepresentation of Quine. This serves not only to clarify Quine's position, but also to crystallize what is and what is not at issue in choosing the model-theoretic account of first-order logical truth over one in terms of substitutions. I conclude by highlighting the need for justifying the belief that the definition of first-order logical truth in terms of models is superior to its definition in terms of substitutions.

In a 1969 paper, Quine coined the term 'limits of decision'. This term evidently refers to limits on the logical vocabulary of a logic, beyond which satisfiability is no longer decidable. In the same paper. Quine showed that not only monadic formulas, but homogeneous k-adic formulas for arbitrary k lie on the decidable side of the limits of decision. But the precise location of the limits of decision has remained an open question. The present paper answers that question. It addresses the question of decidability of those sublogics of first-order logic that are defined in terms of their logical vocabularies. A complete answer is obtained, thus locating exactly Quine's limits of decision.