Three leading philosopher-logicians present a clear and concise overview of formal theories of truth, explaining key logical techniques. Truth is as central topic in philosophy: formal theories study the connections between truth and logic, including the intriguing challenges presented by paradoxes like the Liar.

Theories of Truth provides a clear, critical introduction to one of the most difficult areas of philosophy. It surveys all of the major philosophical theories of truth, presenting the crux of the issues involved at a level accessible to nonexperts yet in a manner sufficiently detailed and original to be of value to professional scholars. Kirkham's systematic treatment and meticulous explanations of terminology ensure that readers will come away from this book with a comprehensive general understanding (...) of one of philosophy's thorniest set of topics. -/- Included are discussions of the correspondence, coherence, pragmatic, semantic, performative, redundancy, appraisal, and truth-as-justification theories. There are also chapters or sections of chapters on the liar paradox, three-valued logic, Field's critique of Tarski, Davidson's program, Dummett's theory of linguistic competence, satisfaction, recursion, the extension/intension distinction, and an explanation of how theories of justification, properly understood, differ from theories of truth. -/- A persistent theme is that philosophers have too often failed to recognize that not all theories of truth are intended to answer the same question. When the various questions are made distinct, it is apparent that many of the "debates" in this field are really cases of philosophers talking past one another. There is much less disagreement within the field than has commonly been thought. (shrink)

T-biconditionals have often been regarded as insufficient as axioms for truth. This verdict is based on Tarski’s observation that the typed T-sentences suffer from deductive weakness. As indicated by McGee, the situation might change radically if we consider type-free disquotational theories of truth. However, finding a well-motivated set of untyped T-biconditionals that is consistent and recursively enumerable has proven to be very difficult. Moreover, some authors ) have argued that any solution to the semantic paradoxes necessarily involves (...) ‘inflationary’ means, thus spelling doom to deflationist and minimalist truth theories in particular. The situation is indeed worrisome as formal theories of minimalist truth are missing so far. This makes it very hard to properly evaluate the tenets of minimalism. In the present article, we will show how to find safe instances of the T-schema just by relying on syntactic features of the sentences of our language—in particular, we will explore Quine’s idea of stratification. Based on that, we will introduce some disquotational truth theories that are deductively very strong. (shrink)

This chapter attempts to give a brief overview of nonclassical (-logic) theories of truth. Due to space limitations, we follow a victory-through-sacrifice policy: sacrifice details in exchange for clarity of big-picture ideas. This policy results in our giving all-too-brief treatment to certain topics that have dominated discussion in the non-classical-logic area of truth studies. (This is particularly so of the ‘suitable conditoinal’ issue: §4.3.) Still, we present enough representative ideas that one may fruitfully turn from this essay (...) to the more-detailed cited works for further study. Throughout – again, due to space – we focus only on the most central motivation for standard non-classical-logic-based truth theories: namely, truth-theoretic paradox (specifically, due to space, the liar paradox). (shrink)

The aim of this paper is to show that it’s not a good idea to have a theory of truth that is consistent but ω-inconsistent. In order to bring out this point, it is useful to consider a particular case: Yablo’s Paradox. In theories of truth without standard models, the introduction of the truth-predicate to a first order theory does not maintain the standard ontology. Firstly, I exhibit some conceptual problems that follow from so introducing it. (...) Secondly, I show that in second order theories with standard semantics the same procedure yields a theory that doesn’t have models. So, while having an ω- inconsistent theory is a bad thing, having an unsatisfiable theory of truth is actually worse. This casts doubts on whether the predicate in question is, after all, a truthpredicate for that language. Finally, I present some alternatives to prove an inconsistency adding plausible principles to certain theories of truth. (shrink)

Partly due to the influence of Tarski's work, it is commonly assumed that any good theory of truth implies biconditionals of the sort mentioned in Convention T: instances of the T-Schema "s is true in L if and only if p" where the sentence substituted for "p" is equivalent in meaning to s. I argue that we must take care to distinguish the claim that implying such instances is sufficient for adequacy in an account of truth from the (...) claim that doing so is necessary. The claim that doing so is sufficient is a common component of deflationary theories of truth, while the claim that it is necessary, though often assumed, must be denied by proponents of rival inflationary theories of truth. I discuss the clarification of the debate between these views of truth that results from distinguishing the necessity and the sufficiency claims, and examine the prospects for its resolution. (shrink)

In this rigorous investigation into the logic of truth Anil Gupta and Nuel Belnap explain how the concept of truth works in both ordinary and pathological..

At the centre of the traditional discussion of truth is the question of how truth is defined. Recent research, especially with the development of deflationist accounts of truth, has tended to take truth as an undefined primitive notion governed by axioms, while the liar paradox and cognate paradoxes pose problems for certain seemingly natural axioms for truth. In this book, Volker Halbach examines the most important axiomatizations of truth, explores their properties and shows how (...) the logical results impinge on the philosophical topics related to truth. In particular, he shows that the discussion on topics such as deflationism about truth depends on the solution of the paradoxes. His book is an invaluable survey of the logical background to the philosophical discussion of truth, and will be indispensable reading for any graduate or professional philosopher in theories of truth. (shrink)

Nonclassical theories of truth have in common that they reject principles of classical logic to accommodate an unrestricted truth predicate. However, different nonclassical strategies give up different classical principles. The paper discusses one criterion we might use in theory choice when considering nonclassical rivals: the maxim of minimal mutilation.

Every deflationist semantic theory has its inflationist correlate: this is the semantic theory the deflationist theory is designed to deflate. This chapter presents Radical Inflationism and Radical Deflationism as stipulatively defined theories, without regard to who might subscribe to them, or to one or another of their parts. Radical Deflationism is based on a view worked out over a number of important publications by Hartry Field. In other words, radical inflationist is on board with the view Hartry Field had (...) when he wrote 'Tarski's theory of truth', that our notions of reference and truth are correspondence notions that stand in need of physicalistic explications. This is that Radical Deflationism's claim that the only reason we need a notion of truth is as a device of disquotation is hostage to the theory's ability to meet what we will presently see is its greatest challenge. (shrink)

Infectious logics are systems that have a truth-value that is assigned to a compound formula whenever it is assigned to one of its components. This paper studies four-valued infectious logics as the basis of transparent theories of truth. This take is motivated as a way to treat different pathological sentences differently, namely, by allowing some of them to be truth-value gluts and some others to be truth-value gaps and as a way to treat the semantic (...) pathology suffered by at least some of these sentences as infectious. This leads us to consider four distinct four-valued logics: one where truth-value gaps are infectious, but gluts are not; one where truth-value gluts are infectious, but gaps are not; and two logics where both gluts and gaps are infectious, in some sense. Additionally, we focus on the proof theory of these systems, by offering a discussion of two related topics. On the one hand, we prove some limitations regarding the possibility of providing standard Gentzen sequent calculi for these systems, by dualizing and extending some recent results for infectious logics. On the other hand, we provide sound and complete four-sided sequent calculi, arguing that the most important technical and philosophical features taken into account to usually prefer standard calculi are, indeed, enjoyed by the four-sided systems. (shrink)

Robert cummins has recently attacked this line of argument: if p is a semantically primitive predicate of a first order language l, then p requires its own clause in the definition of satisfaction integral to a definition of truth of l. thus if l has infinitely many such p, the satisfaction clause cannot be completed and truth for l will remain undefined. against this cummins argues that a single clause in a general base theory for l can specify (...) satisfaction conditions for even infinitely many semantically primitive predicates of l. against cummins we argue that a general base theory contains a primitive expression 'applies to' and that to make his case cummins would need to prove this expression stands for a semantical relation sufficient to a truth definition for l. not only is such a proof lacking but we show the claim to be altogether dubious. (shrink)

The solution John Buridan offers for the Paradox of the Liar has not been correctly placed within the framework of his philosophy of language. More precisely, there are two important points of the Buridanian philosophy of language that are crucial to the correct understanding of his solution to the Liar paradox that are either misrepresented or ignored in some important accounts of his theory. The first point is that the Aristotelian formula, ` propositio est vera quia qualitercumque significat in rebus (...) significatis ita est ', once amended, is a correct way to talk about the truth of a sentence. The second one is that he has a double indexing theory of truth: a sentence is true in a time about a time, and such times should be distinguished in the account of the truth-conditions of sentences. These two claims are connected in an important way: the Aristotelian formula indicates the time about which a sentence is true. Some interpreters of the Buridanian solution to the paradox, following the lead of Herzberger, have missed these points and have been led to postulate truth-values gaps, or surrogates of truth-value gaps, when there is nothing of this sort in his theory. I argue against this tradition of interpretation of Buridan and propose an interpretation of his solution to the Liar. (shrink)

This article outlines what a formal theory of truth should be like, at least at first glance. As not all of the stated constraints can be satisfied at the same time, in view of notorious semantic paradoxes such as the Liar paradox, we consider the maximal consistent combinations of these desiderata and compare their relative advantages and disadvantages.

Substructural theories of truth are theories based on logics that do not include the full complement of usual structural rules. Existing substructural approaches fall into two main families: noncontractive approaches and nontransitive approaches. This paper provides a sketch of these families, and argues for two claims: first, that substructural theories are better-positioned than other theories to grapple with the truth-theoretic paradoxes, and second—more tentatively—that nontransitive approaches are in turn better-positioned than noncontractive approaches.

Neo-Kantian philosophers sometimes divided the history of philosophy in three periods: philosophy before Kant, Kant, and philosophy after Kant. The admirers of Alfred Tarski are prone, with good justification, to propose a similar division of theories of truth. But even in our post-Tarskian period, the nature and significance of Tarski’s theory of truth is still a matter of controversy.1 Therefore, to understand better Tarski’s achievement and some of our present puzzles, it is instructive to go back to (...) the pre-Tarskian problem situation in the late 1920s and the early 1930s, and to see how Tarski’s treatment of truth in Warsaw was related to alternative views current in Vienna and Berlin. (shrink)

Paul Foulkes; V*—Theories of Truth, Proceedings of the Aristotelian Society, Volume 77, Issue 1, 1 June 1977, Pages 63–72, https://doi.org/10.1093/aristotelian/.

Primitivists about truth maintain that truth cannot be analysed in more fundamental terms. Defences of primitivism date back to the early years of analytic philosophy, being offered by G.E. Moore, Bertrand Russell, and Gottlob Frege. In more recent years, a number of contemporary philosophers—including Donald Davidson, Ernest Sosa, Trenton Merricks, Douglas Patterson, and Jamin Asay—have followed suit, defending their own versions of primitivism. I'll begin by offering a brief history of primitivism, situating each of these views within the (...) landscape of primitivist truth theories and detailing some of their core motivations and apparent shortcomings. To close the discussion, I'll offer a diagnosis of the prospects of primitivism, focusing on the mystery challenge, which has loomed large throughout the history of primitivist truth theories, and the methodology that should be used in evaluating primitivist (and other) truth theories going forward. (shrink)

This chapter surveys standard theories of truth, and argues that they are all compatible with dialetheism.

The paradoxes about truth are the subject of extensive research. Developing an original approach, this book argues that we should diverge from classical logic and presents a number of formal theories of truth. Also included is a beginner-friendly introduction to semantic paradoxes, and a discussion of alternative non-classical theories.

This chapter discusses formal theories of truth: the redundancy theory and its ilk, distinguished by the attempt to characterize truth in terms of its structural properties, in the context of the position adopted by Putnam in his John Dewey Lectures, here styled ‘Common-sense Realism’. This position is described, combining two principles called the Thesis of the Internality and the Thesis of World-Embeddedness, with a formal account of truth. It is argued that Common-sense Realism, along with all (...) theories comprising a formal account of truth, should be committed to the flames, because they are cut off from exploiting the Fregean model of meaning, based on a recursion on truth. (shrink)

There are often said to be five main 'theories of truth': correspondence, coherence, pragmatic, redundancy, and semantic theories. The coherence theory of truth equates the truth of a judgment with its coherence with other beliefs. Different versions of the theory give different accounts of coherence, but in all its forms the point is to exhibit truth as an internal relation between beliefs. The pragmatic theory of truth is akin to a coherence theory of (...) this Kantian kind. No coherence theorist need deny the uncontentious claim that for a judgment to be true is for it to stand in a certain relationship, which can be called correspondence, with some state of affairs in the world. The conflict with the redundancy theory may be more apparent than real. For the redundancy theory is not a theory of what truth consists in, but a theory about the meaning of the words 'is true'. (shrink)

While Kripke's original paper on the theory of truth used a three-valued logic, we believe a four-valued version is more natural. Its use allows for possible inconsistencies in information about the world, yet contains Kripke's development within it. Moreover, using a four-valued logic makes it possible to work with complete lattices rather than complete semi-lattices, and thus the mathematics is somewhat simplified. But more strikingly, the four-valued version has a wide, natural generalization to the family of interlaced bilattices. Thus, (...) with little more work, the theory is extended to a broad class of settings. Indeed, a result like Theorem 6.2 would not even be possible to state without the interlaced bilattice machinery. We hope the notion of interlaced bilattice will make apparent further such connections. (shrink)

The main aim of our paper was to present three formal tools for comparing various axiomatic theories of truth. In Section 2 we aimed at showing that there are indeed many different approaches to defining a set of axioms for the notion of truth. In Section 3 we introduced three different \measures of strength" of axiomatic theories of truth, i.e. three reflexive and transitive relations on the set of axiomatic theories of truth. We (...) have explained the intuition behind each of them. The three relations were called : Fujimoto definability, model-theoretical strength, proof-theoretical strength. Then in the last section we described how they order the truth theories introduced in Section 2. We observed that theories made equivalent by the coarser relation can be strictly ordered by the next one. (shrink)

History and Philosophy of Logic, Volume 33, Issue 1, Page 99-100, February 2012.

Prosentential theorists claim that sentences such as “That’s true” are prosentences that function analogously to their better known cousins–pronouns. For example, just as we might use the pronoun ‘he’ in place of ‘James’ to transform “James went to the supermarket” into “He went to the supermarket,” so we might use the prosentenceforming operator ‘is true’ to transform “Snow is white” into “‘Snow is white’ is true.” According to the prosentential theory of truth, whenever a referring expression (for example, a (...) definite description or a quote-name) is joined to the truth predicate, the resulting statement contains no more content than the sentence(s) picked out by the referring expression. To assert that a sentence is true is simply to assert or reassert that sentence; it is not to ascribe the property of truth to that sentence. The prosentential theory is one kind of deflationary theory of truth. Like all deflationary theories, it provides an alternative to explanations of truth that analyze truth in terms of reference, predicate satisfaction or a correspondence relation. (shrink)

Definitional and axiomatic theories of truth -- Objects of truth -- Tarski -- Truth and set theory -- Technical preliminaries -- Comparing axiomatic theories of truth -- Disquotation -- Classical compositional truth -- Hierarchies -- Typed and type-free theories of truth -- Reasons against typing -- Axioms and rules -- Axioms for type-free truth -- Classical symmetric truth -- Kripke-Feferman -- Axiomatizing Kripke's theory in partial logic -- Grounded (...) class='Hi'>truth -- Alternative evaluation schemata -- Disquotation -- Classical logic -- Deflationism -- Reflection -- Ontological reduction -- Applying theories of truth. (shrink)

The Revision Theory of Truth has been challenged in A. M. Yaqūb's recent book The Liar Speaks the Truth. Yaqūb suggests some non-trivial changes in the original theory - changing the limit rule - to avoid certain artifacts. In this paper it is shown that the proposed changes are not sufficient, i.e., Yaqūb's system also produces artifacts. An alternative solution is proposed and the relation between it and Yaqūb's solution is explored.

We introduce a subclass of Kripke's fixed points in which falsehood is the preferred truth value. In all of these the truthteller evaluates to false, while the liar evaluates to undefined (or overdefined). The mathematical structure of this family of fixed points is investigated and is shown to have many nice features. It is noted that a similar class of fixed points, preferring truth, can also be studied. The notion of intrinsic is shown to relativize to these two (...) subclasses. The mathematical ideas presented here originated in investigations of so-called stable models in the semantics of logic programming. (shrink)

We consider various concepts associated with the revision theory of truth of Gupta and Belnap. We categorize the notions definable using their theory of circular definitions as those notions universally definable over the next stable set. We give a simplified account of varied revision sequences-as a generalised algorithmic theory of truth. This enables something of a unification with the Kripkean theory of truth using supervaluation schemes.

Quine argues, in “On the Nature of Moral Values” that a coherence theory of truth is the “lot of ethics”. In this paper, I do a bit of work from within Quinean theory. Specifically, I explore precisely what a coherence theory of truth in ethics might look like and what it might imply for the study of normative value theory generally. The first section of the paper is dedicated to the exposition of a formally correct coherence truth (...) predicate, the possibility of which has been the subject of some skepticism. In the final two sections of the paper, I claim that a coherence theory in ethics does not reduce the practice of moral inquiry to absurdity, in practice as well as in principle. (shrink)

Saul Kripke’s theory of truth suffers from expressive limitations – in particular, there are no extensional operators within that framework that allow one to characterize those sentences that fail to receive a truth value within the framework. Especially worrisome is the fact that there is no operator that outputs true on exactly the paradoxical sentences. In this paper I extend Kripke’s approach via the addition of extensional operators, which allows us to characterize many (but not all) such sentences, (...) including the paradoxical ones. (shrink)

In this second and last paper of the two part investigation on "Modality and Axiomatic Theories of Truth" we apply a general strategy for constructing modal theories over axiomatic theories of truth to the theory Kripke-Feferman. This general strategy was developed in the first part of our investigation. Applying the strategy to Kripke-Feferman leads to the theory Modal Kripke-Feferman which we discuss from the three perspectives that we had already considered in the first paper, where (...) we discussed the theory Modal Friedman-Sheard. That is, we first show that Modal Kripke-Feferman preserves theoremhood modulo translation with respect to modal operator logic. Second, we develop a modal semantics fitting the newly developed theory. Third, we investigate whether the modal predicate of Modal Kripke-Feferman can be understood along the lines of a proposal of Kripke, namely as a truth predicate modified by a modal operator. (shrink)

This book argues that correspondence theories of truth fail because the relation that holds between a true thought and a fact is that of identity, not correspondence. Facts are not complexes of worldly entities which make thoughts true they are merely true thoughts. According to Julian Dodd, the resulting modest identity theory, while not defining truth, correctly diagnoses the failure of correspondence theories, and thereby prepares the ground for a defensible deflation of the concept of (...) class='Hi'>truth. (shrink)

We define an applicative theory of truth TPTTPT which proves totality exactly for the polynomial time computable functions. TPTTPT has natural and simple axioms since nearly all its truth axioms are standard for truth theories over an applicative framework. The only exception is the axiom dealing with the word predicate. The truth predicate can only reflect elementhood in the words for terms that have smaller length than a given word. This makes it possible to achieve (...) the very low proof-theoretic strength. Truth induction can be allowed without any constraints. For these reasons the system TPTTPT has the high expressive power one expects from truth theories. It allows embeddings of feasible systems of explicit mathematics and bounded arithmetic.The proof that the theory TPTTPT is feasible is not easy. It is not possible to apply a standard realisation approach. For this reason we develop a new realisation approach whose realisation functions work on directed acyclic graphs. In this way, we can express and manipulate realisation information more efficiently. (shrink)

In this investigation we explore a general strategy for constructing modal theories where the modal notion is conceived as a predicate. The idea of this strategy is to develop modal theories over axiomatic theories of truth. In this first paper of our two part investigation we develop the general strategy and then apply it to the axiomatic theory of truth Friedman-Sheard. We thereby obtain the theory Modal Friedman-Sheard. The theory Modal Friedman-Sheard is then discussed from (...) three different perspectives. First, we show that Modal Friedman-Sheard preserves theoremhood modulo translation with respect to modal operator logic. Second, we turn to semantic aspects and develop a modal semantics for the newly developed theory. Third, we investigate whether the modal predicate of Modal Friedman-Sheard can be understood along the lines of a proposal of Kripke, namely as a truth predicate modified by a modal operator. (shrink)

The sentences employed in semantic paradoxes display a wide range of semantic behaviours. However, the main theories of truth currently available either fail to provide a theory of paradox altogether, or can only account for some paradoxical phenomena by resorting to multiple interpretations of the language. In this paper, I explore the wide range of semantic behaviours displayed by paradoxical sentences, and I develop a unified theory of truth and paradox, that is a theory of truth (...) that also provides a unified account of paradoxical sentences. The theory I propose here yields a threefold classification of paradoxical sentences – liar-like sentences, truth-teller-like sentences, and revenge sentences. Unlike existing treatments of semantic paradox, the theory put forward in this paper yields a way of interpreting all three kinds of paradoxical sentences, as well as unparadoxical sentences, within a single model. (shrink)

SummaryIn developing his claim that meaning cannot be understood independently of truth, Donald Davidson argues that a theory of meaning will take the form of a Tarskian theory of truth. In this essay I seek to describe more fully the structure of a Davidsonian theory of meaning and the extent to which Davidson modifies Tarski's account. 1 consider and reject John Foster's claim that Davidson takes, or should take, truth as a formal primitive, and argue that it (...) is Davidson's principle of charity which plays the essential role in giving theories of truth empirical application. (shrink)

There is no distinct correspondence theory of truth, truth is correspondence to fact. If facts are taken to be true propositions, we wind up with just another version of the correspondence theory's ostensible competitor, the redundancy theory of truth. If instead facts are taken to be Armstrong's states of affairs, or Tractarian facts, or Mellor's _facta<D>, we get a _truthmaker<D> principle, that for every truth there is a truthmaker; something whose existence implies the proposition in question. (...) Truthmaker principles are interesting and useful, but go far beyond truth as correspondence with fact, and so are not really theories of truth at all. (shrink)

In this entry, we offer a very brief overview of Dorothy Grover's prosentential theory of truth.

We investigate how to assign probabilities to sentences that contain a type-free truth predicate. These probability values track how often a sentence is satisfied in transfinite revision sequences, following Gupta and Belnap’s revision theory of truth. This answers an open problem by Leitgeb which asks how one might describe transfinite stages of the revision sequence using such probability functions. We offer a general construction, and explore additional constraints that lead to desirable properties of the resulting probability function. One (...) such property is Leitgeb’s Probabilistic Convention T, which says that the probability of φ equals the probability that φ is true. (shrink)