Online research in philosophy

Transparency is the following (alleged) property of truth: if one possesses the concept of truth, then to assert, believe, inquire whether it is true that S just is to assert, believe, inquire whether S (and conversely). It might appear (as it did to Frege in 'Thoughts') that if truth ascriptions were transparent, then the truth predicate must be redundant; but the fact that some truth ascriptions are not transparent-for instance, those that quantify over, name, or describe the proposition(s) to which truth is ascribed-shows that the truth predicate could not be redundant. It is argued that the apparent paradox is resolved by treating content as more basic than truth (and arguing, accordingly, that content cannot be explained, even in part, in terms of truth conditions). This strategy is illustrated by three candidate analyses, each of which treats the truth predicate as non-redundant but can, nevertheless, account for transparency.

In reply to Geach's objection against expressivism, some have claimed that there is a plurality of truth predicates. I raise a difficulty for this claim: valid inferences can involve sentences assessable by any truth predicate, corresponding to 'lightweight' truth as well as to 'heavyweight' truth. To account for this, some unique truth predicate must apply to all sentences that can appear in inferences. Mixed inferences remind us of a central platitude about truth: truth is what is preserved in valid inferences. The question is why we should postulate truth predicates that do not satisfy this platitude.

For many, the paradigm of a deflationary theory of truth is the redundancy theory, which is typically taken to consist of two claims: namely (i) that sentences containing the truth predicate are synonymous with sentences not containing the truth predicate (and so the truth predicate is redundant) and (ii) that there is no property of truth.1 The redundancy theory is not an attractive theory of truth since neither of its claims is particularly plausible on its own, and the combination of the two claims is, if not actually inconsistent, at least uncomfortable.2 Very few deflationists nowadays endorse either part of the theory.

The aim of the paper is to formulate rules of inference for the predicate 'is true' applied to sentences. A distinction is recognised between (ordinary) truth and definite truth and consequently between two notions of validity, depending on whether truth or definite truth is the property preserved in valid arguments. Appropriate sets of rules of inference governing the two predicates are devised. In each case the consequence relation is in harmony with the respective predicate. Particularly appealing is a set of ND rules for ordinary truth in which premises and assumptions play different roles, premises being taken to assert definite truth, assumptions to suppose truth. This set of rules can be said to capture everyday reasoning with truth. Also presented are formal characterisations, in the meta-language and in the object language, of paradoxical and 'truth teller'-like sentences.

Joan Weiner has recently claimed that Frege neither uses, nor has any need to use, a truth-predicate in his justification of the logical laws. She argues that because of the assimilation of sentences to proper names in his system, Frege does not need to make use of the Quinean device of semantic ascent in order to formulate the logical laws, and that the predicate ‘is the True’, which is used in Frege's justification, is not to be considered as a truth-predicate, because it does not apply to true sentences or true thoughts. The present paper aims to show that Frege needs to use, and does use, a truth-predicate in this context. It is argued, first, that Frege needs to use a truthpredicate in order to show that the truth of the logical laws is evident from the senses of the sentences by means of which they are formulated, and second, that the predicate that he actually uses, ‘is the True’, must be considered as a truth-predicate in the relevant sense, because it can be used and is actually used by Frege to explain the truth-conditions of thoughts. To defend this interpretation, it is discussed whether the explanatory use of ‘is the True’ in Frege's system is compatible with his deflationary analysis of ‘true’. The paper's conclusion is that there is indeed a conflict here; but, from Frege's point of view, this conflict is due merely to the logical imperfection of natural language and does not affect the proper system but only its propaedeutic. CiteULike    Connotea    Del.icio.us    What's this?

Propositional logic -- Propositions and arguments -- Connectives and argument forms -- Truth tables -- Trees -- Vagueness and bivalence -- Conditionality -- Natural deduction -- Predicate logic -- Predicates, names, and quantifiers -- Models for predicate logic -- Trees for predicate logic -- Identity and functions -- Definite descriptions -- Some things do not exist -- What is a predicate? -- What is logic?

Some fourteenth-century treatises on paradoxes of the liar family offer a promising starting-point for the formulation of full-fledged theories of truth with systematic relevance in their own right. In particular, Bradwardine's thesis that sentences typically say more than one thing gives rise to a quantificational approach to truth, and Buridan's theory of truth based on the notion of suppositio allows for remarkable metaphysical parsimony. Bradwardine's and Buridan's theories both have theoretical advantages, but fail to provide a satisfactory account of truth because both are committed to the thesis, fatal for both, that every sentence signifies/implies its own truth. I close with remarks on Greg Restall's recent model-theoretic formalization of Bradwardine's theory of truth.

I argued that Frege does not have a metatheory in the following sense: the justifications he offers for his basic laws and rules of inference neither employ nor require a truth-predicate or metalinguistic variables. In ‘Does Frege Use a Truth-predicate in his "Justification" of the Laws of Logic?’, Dirk Greimann disputes this. As Greimann interprets Frege, (i) Frege's remarks commit him to giving a metatheoretic justification of the basic laws and rules of his logic, and (ii) Frege actually gives such a justification in the early sections of Grundgesetze—although the truth-predicate that Frege employs is a non-standard one: it is neither a predicate that holds of all and only true sentences nor a predicate that holds of all and only true thoughts. I argue that Greimann's interpretation is not, in the end, true to the text, and that his non-standard view of what is required of a Tarskian truth-predicate is ultimately not viable. CiteULike    Connotea    Del.icio.us    What's this?

It has been proposed that the law of non-contradiction be revised to permit the simultaneous truth and falsity of the key sentences of the logical paradoxes, e.g., This sentence is false. In an attempt to show to what extent this bizarre suggestion of inconsistent models or truth-value gluts is a coherent suggestion it is proved that a first-order language for number theory can be semantically closed by having its own global truth predicate under some non-standard interpretation and thus that it actually can contain the Liar sentence. It is proved that in this interpretation the Liar sentence is both true and false, although not every sentence is.

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.