Tarski’s Convention T is often taken to claim that it is both sufficient and necessary for adequacy in a definition of truth that it imply instances of the T-schema where the embedded sentence translates the mentioned sentence. However, arguments against the necessity claim have recently appeared, and, furthermore, the necessity claim is actually not required for the indefinability results for which Tarski is justly famous; indeed, Tarski’s own presentation of the results in the later Undecidable Theories makes (...) no mention of an assumption to the effect that the definition of truth implies the biconditionals. This raises a question: was Tarski in fact committed to the necessity claim in the important papers of the 1930s and 40s? I argue that he was not. The discussion of this apparently esoteric interpretive issue in fact gets to the heart of many important questions about truth, and in the final sections of the paper I discuss the importance of the T-biconditionals in the theory of meaning and the relation of deflationary and inflationary theories of truth to the semantic paradoxes. (shrink)

Tarski avoids the liar paradox by relativizing truth and falsehood to particular languages and forbidding the predication to sentences in a language of truth or falsehood by any sentences belonging to the same language. The Tarski truth-schemata stratify an object-language and indefinitely ascending hierarchy of meta-languages in which the truth or falsehood of sentences in a language can only be asserted or denied in a higher-order meta-language. However, Tarski’s statement of the truth-schemata themselves involve general truth functions, (...) and in particular the biconditional, defined in terms of truth conditions involving truth values standardly displayed in a truth table. Consistently with his semantic program, all such truth values should also be relativized to particular languages for Tarski. The objection thus points toward the more interesting problem of Tarski’s concept of the exact status of truth predications in a general logic of sentential connectives. Tarski’s three-part solution to the circularity objection which he anticipates is discussed and refuted in detail. (shrink)

Halbach has argued that Tarski biconditionals are not ontologically conservative over classical logic, but his argument is undermined by the fact that he cannot include a theory of arithmetic, which functions as a theory of syntax. This article is an improvement on Halbach's argument. By adding the Tarski biconditionals to inclusive negative free logic and the universal closure of minimal arithmetic, which is by itself an ontologically neutral combination, one can prove that at least one thing (...) exists. The result can then be strengthened to the conclusion that infinitely many things exist. Those things are not just all Gödel codes of sentences but rather all natural numbers. Against this background inclusive negative free logic collapses into noninclusive free logic, which collapses into classical logic. The consequences for ontological deflationism with respect to truth are discussed. (shrink)

Alfred Tarski (1901--1983) is widely regarded as one of the two giants of twentieth-century logic and also as one of the four greatest logicians of all time (Aristotle, Frege and Gödel being the other three). Of the four, Tarski was the most prolific as a logician. The four volumes of his collected papers, which exclude most of his 19 monographs, span over 2500 pages. Aristotle's writings are comparable in volume, but most of the Aristotelian corpus is not about (...) logic, whereas virtually everything written by Tarski concerns logic more or less directly. There is no doubt that Tarski wrote more on logic than any other author; he started publishing on logic in 1921 at the age of 20 and continued until his death at the age of 82. Two of his works appeared posthumously [Hist. Philos. Logic 7 (1986), no. 2, 143--154; MR0868748 (88b:03010); Tarski and Givant, A formalization of set theory without variables, Amer. Math. Soc., Providence, RI, 1987; MR0920815 (89g:03012)]. Tarski's voluminous writings were widely scattered in numerous journals, some quite rare. It has been extremely difficult to study the development of Tarski's thought and to trace the interconnections and interdependence of his various papers. Thanks to the present collection all this has changed, and it is likely that the increased accessibility of Tarski's papers will have the effect of increasing Tarski's already enormous influence. (shrink)

The current paper studies the formal properties of the Global Reflection Principle, to wit the assertion “All theorems of$\mathrm {Th}$are true,” where$\mathrm {Th}$is a theory in the language of arithmetic and the truth predicate satisfies the usual Tarskian inductive conditions for formulae in the language of arithmetic. We fix the gap in Kotlarski’s proof from [15], showing that the Global Reflection Principle for Peano Arithmetic is provable in the theory of compositional truth with bounded induction only ($\mathrm {CT}_0$). Furthermore, we (...) extend the above result showing that$\Sigma _1$-uniform reflection over a theory of uniform Tarski biconditionals ($\mathrm {UTB}^-$) is provable in$\mathrm {CT}_0$, thus answering the question of Beklemishev and Pakhomov [2]. Finally, we introduce the notion of a prolongable satisfaction class and use it to study the structure of models of$\mathrm {CT}_0$. In particular, we provide a new model-theoretical characterization of theories of finite iterations of uniform reflection and present a new proof characterizing the arithmetical consequences of$\mathrm {CT}_0$. (shrink)

This dissertation is a study of some recent theories of truth. The theories fall into three groups: The Revision Theories, the context-sensitive theories, and the "Chrysippian theories". ;The "Chrysippian theories" are based on the intuition that pathologicalities arising from the concept of truth can be recognized and acknowledged with the concept of truth itself. Thus, from the pathologicality of the Liar, for example, we can conclude that the Liar is not true. This leads to immediate difficulties since the Liar claims (...) just that--that it is not true--and it would thus seem to be true. The Chrysippian theories are designed to avoid these difficulties while preserving the motivating intuition. Haim Gaifman's Pointer Semantics, and Brian Skyrms' Intensional Fixed-Point Theory of Truth are examples of such theories. They are exposited and criticized. ;The context-sensitive theories dealt with are Tyler Burge's Indexical Theory of Truth and the theory of Jon Barwise and John Etchemendy. These theories claim that an ambiguity due to a contextual parameter is the reason for the difficulties we encounter. Burge offers a theory of Tarskian levels coupled with a pragmatic theory that explains the assignment of levels to occurrences of 'true'. Barwise and Etchemendy make explicit a situational parameter in their account of propositions. They consider the ambiguity with respect to the situation a propositions is about a main source of the paradoxes. ;Finally, the Revision Theories of Truth of Anil Gupta and Nuel Belnap and two variations of this theory are considered. One is due to Aladdin Yaqub, the other, the "fully-varied theory", is due to Gupta and Belnap but remains largely unexplored. Revision theories are put forward as the most promising account of the difficulties. They are based on a definitional reading of all Tarski biconditionals. The circularity implied by such a reading is handled by Gupta's and Belnap's general theory of definitions. ;Yaqub's objections raised against the standard theory are examined, and his proposed solution is shown to be inadequate. The fully-varied Revision Theory is shown to provide a better solution. (shrink)

The epistemic paradox of 'belief instability' has recently received notable attention from many philosophers. Understanding this paradox is very important because belief is a central notion of psychologically motivated semantic theories in philosophy, linguistics, and cognitive science, and this paradox poses serious problems for these theories. In this dissertation I criticize previous proposals and offer a new proposal, which I call a 'revision theory of belief'. -/- My revision theory of belief is in many respects an application of Gupta's and (...) Belnap's revision theory of truth, which is proposed to deal with the Liar paradox. They argue that truth is a circular notion because Tarski biconditionals provide circular, partial definitions of truth. And this circularity of truth is the source of the Liar paradox. I offer a similar proposal for handling the paradox of belief instability. In particular, I argue that our notion of belief involved in the paradox of belief instability is circular, and that is why this paradox arises. -/- If the notion of belief involved in the paradox is circular, we have to employ a hypothetical evaluation of the belief predicate, and if we do so through a revision process, we can avoid the contradiction which seems to be generated by some paradoxical belief sentences. But it is not easy to show that our notion of belief is circular. Especially, there is nothing like Tarski biconditionals in the case of belief. Nonetheless, I show in this dissertation that there is a certain schema, which I call the B-schema, whose instances can be taken as circular, partial definitions of a notion of belief, and it is that notion of belief which is involved in the paradox of belief instability. In this dissertation I also show that the revision approach can be extended for handling the Knower paradox. I argue that the Knower paradox arises because our notion of knowledge involved in the paradox is circular. (shrink)

The epistemic paradox of 'belief instability' has recently received notable attention from many philosophers. Understanding this paradox is very important because belief is a central notion of psychologically motivated semantic theories in philosophy, linguistics, and cognitive science, and this paradox poses serious problems for these theories. In this dissertation I criticize previous proposals and offer a new proposal, which I call a 'revision theory of belief'. ;My revision theory of belief is in many respects an application of Gupta's and Belnap's (...) revision theory of truth, which is proposed to deal with the Liar paradox. They argue that truth is a circular notion because Tarski biconditionals provide circular, partial definitions of truth. And this circularity of truth is the source of the Liar paradox. I offer a similar proposal for handling the paradox of belief instability. In particular, I argue that our notion of belief involved in the paradox of belief instability is circular, and that is why this paradox arises. ;If the notion of belief involved in the paradox is circular, we have to employ a hypothetical evaluation of the belief predicate, and if we do so through a revision process, we can avoid the contradiction which seems to be generated by some paradoxical belief sentences. But it is not easy to show that our notion of belief is circular. Especially, there is nothing like Tarski biconditionals in the case of belief. Nonetheless, I show in this dissertation that there is a certain schema, which I call the B-schema, whose instances can be taken as circular, partial definitions of a notion of belief, and it is that notion of belief which is involved in the paradox of belief instability. In this dissertation I also show that the revision approach can be extended for handling the Knower paradox. I argue that the Knower paradox arises because our notion of knowledge involved in the paradox is circular. (shrink)

We are grateful to Professor Robert Koons for his excellent, and generous, review (henceforth KR) of our book The Revision Theory of Truth (henceforth RTT). Koons provides in KR a welcome guide to our RTT, and he puts forward objections that deserve serious consideration. In this note we shall respond only to his principal objection.' This objection, which is developed on pp. 625 — 628 of KR, calls into question our main thesis. As we argue below, however, the objection is (...) not successful. We should forewarn the reader that this note is not self-contained. It presupposes familiarity with RTT (primarily, Chapter 4) and with KR. The main thesis of RTT is that truth is a circular concept. We argued that the Tarski biconditionals, read as partial definitions, constitute an intensionally adequate definition of truth. In other words, if T is a predicate defined by the Tarski-style infinitistic definition (I). (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 papers discuss the place, if any, of Convention T (the condition of material adequacy of the proper definition of truth formulated by Tarski) in the truth-makers account offered by Kevin Mulligan, Peter Simons and Barry Smith. It is argued that although Tarski’s requirement seems entirely acceptable in the frameworks of truth-makers theories for the first-sight, several doubts arise under a closer inspection. In particular, T-biconditionals have no clear meaning as sentences about truth-makers. Thus, truth-makers theory cannot (...) be considered as the semantic theory of truth enriched by metaphysical (ontological) data. The problem of truth-makers for sentences about future events is discussed at the end of the paper. (shrink)

-/- A schema (plural: schemata, or schemas), also known as a scheme (plural: schemes), is a linguistic template or pattern together with a rule for using it to specify a potentially infinite multitude of phrases, sentences, or arguments, which are called instances of the schema. Schemas are used in logic to specify rules of inference, in mathematics to describe theories with infinitely many axioms, and in semantics to give adequacy conditions for definitions of truth. -/- 1. What is a Schema? (...) 2. Uses of Schemas 3. The Ontological Status of Schemas 4. Schemas in the History of Logic Bibliography. (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)

The aim of this paper is rather modest: we do not intend to reconstruct Aristotle’s theory of truth (although we are convinced that there is such a thing), and we will not try to settle the issue concerning Bivalence in Aristotle. We merely want, on the one hand, to argue for the consistency between the main Aristotelian texts on truth and a possible rejection of Bivalence; and on the other hand, to investigate the conditions of a possible counterexample to Bivalence. (...) The motivation for this research is also very specific. We are interested in the apparent violation of Bivalence introduced by vague predicates, and in particular we want to respond to a family of arguments put forward by T. Williamson in support of the idea that allowing for exceptions to Bivalence would be incoherent. We have focused on these arguments for two reasons. On the one hand, what is allegedly threatened by a denial of Bivalence is no less than the very “nature of truth or falsity”. On the other hand, Aristotle is explicitly mentioned as one of the defendants of this “natural” conception of truth, and we are reminded about the connection between Aristotle’s theory and Tarski’s semantic conception. These arguments, therefore, give us an occasion to explore Aristotle’s analysis of the nature of truth and falsity, and to examine its connection with the Tarskian conception of truth. In particular, we would like to question the assumption, which has become a commonplace in the field of analytical philosophy, that Aristotle’s notion of truth can be encoded in the pair of disquotational biconditionals that derive from Tarski’s “T schema”. (shrink)

This collection, with an agreeable proportion of new material and a sensible selection of old, is worth the money and ought to be on the shelf of anyone interested in recent work on language by philosophers, psychologists, and linguists. The section by linguists proper is the longer and more up to date but this seems quite in order: today neither work in philosophy nor psychology can provide a plausible center-of-attention that will take in the other and linguistics as flanking material. (...) For better and worse linguistics is the centerpiece: and the debate between "interpretive" and "generative" semanticists, here respectively represented by Chomsky and George Lakoff, is the center, most likely, of the centerpiece. The generative semanticists suggest that the base and semantic components ultimately come to the same: the distinction between syntactic rules and semantic rules is presumed as in the Chomskian position but it is thought that the algorithm of wellformedness will turn out to provide all the rules needed for semantic interpretation. The interpretive semantic alternative, here argued by Chomsky in a paper otherwise difficult to obtain except in mimeo, distinguishes semantic from base component by insisting, particularly in matters respecting reference and quantification, that transformations are not meaning-invariant, and that, hence, the semantic component is fed by both the base and surface structures independently. To put the interpretive view in terms of Tarski-cum-Davidsonian biconditionals, we would no longer have on the left side of the biconditional one ’structural-descriptive’ string but rather two separate strings, one surface and the other deep, that would jointly and independently determine meaning. The generative semanticists, following James McCawley, stress that their argument against autonomous deep syntax follows in form Morris Halle’s well-known argument against a phonemic level of description supposed intermediate between superficial surface syntax and systematic phonetics. The basic question one raises against this argument is whether logico-semantic form constitutes itself for linguistic science as one level of description and as an essentially linguistic level of description. One can see an obvious place for philosophers in these arguments, though one finds in this volume very little suggestion of philosophical-semantic work, in the Frege-Carnap tradition, that Donald Davidson, Richard Montague, John Wallace, etc., have been carrying on lately. There is a previously unpublished paper by David Wiggins in this vein, but though Wiggins is his usual brilliant and playfully convoluted self, this is too idiosyncratic and occasional a piece to represent what is by way of a movement. Indeed, aside from the Wiggins-Alston material, the philosopher’s section is solid but familiar material: H. P. Grice’s famous paper on meaning and Paul Ziff’s criticism of Grice’s theory; Gilbert Harman’s "Three Levels of Meaning"; late-1960s papers by Donnellan, Linsky, Quine, Strawson, Vendler, and Searle on reference. But this aside this volume vividly makes the point that philosophy and linguistics have never been more entangled with each other in a genuine working relationship. Chomsky’s arguments come in part from recent philosopher’s work. There is evident concern by linguists with presuppositions and performatives. "Fact," an important and not easily available paper by Paul and Carol Kilparski, sparks the philosophic imagination—as do new pieces on lexical entries, semantic features, and categories by Charles Fillmore, Manfried Bierwisch, and others. Almost enough to justify J. L. Austin’s hopes for a joint endeavor of linguists, philosophers, and psychologists: one sees in the footnotes and bibliographies, in the issue and vocabulary, that disciplines are joining and reflecting upon each other in day-to-day work. The psychology section also contains one large new piece: a splendidly energetic defense of linguistic behaviorism by Charles Osgood. One finds balance for this in Jerry Fodor’s "Could meaning be an rm?" And some good, current, and often not easily available material by George Miller, Eric Lennberg, and others. The "overviews" for the various sections are quite distinguished themselves: but this is only in keeping with general character of this reader.—J. L. (shrink)

J. L. Austin, in "Ifs and Cans," proclaimed the common hope that we soon "may see the birth, through the joint labors of philosophers, grammarians, and numerous other students of language, of a true and comprehensive science of language." The problem has always been with the "joint labors" part. Philosophers have always been willing to issue linguists dictums and linguists have been happy to teach philosophers "plain facts." Austin’s general view of language, and his particular notion of performative utterance, can (...) be found in the writing of J. R. Firth, the most commanding British linguist of Austin’s generation, but Austin never refers to Firth. In the present volume, however, we find clear and exciting evidence of genuinely joint labors on the part of philosophers and linguists. They stem from a summer conference in 1969 rounded out with contributions from notables. To two thick issues of Synthese the editors have added a dazzling piece by Saul Kripke, two substantial pieces by James McCawley and J. R. Ross, a short paper by Paul Ziff, and a reprint of P. F. Strawson’s "Grammar and Philosophy." This is an invaluable book and the best book among the many now available concerning the interaction of linguistics and philosophy: worth the cost, which the contributors attempted to reduce through foregoing royalties. The philosophers in this volume hold, or hold intriguing, the view that the semantics of a natural language can and must, in effect, be a theory of truth for a language in much the manner that Tarski suggested, and provided, for artificial language: the recursive specification of biconditionals in which the left hand gives the structural description of an object language sentence and the right hand, the truth conditions in the metalanguage. In "homophonic" translation this requirement can be trivially satisfied simply by mentioning the sentence on the left that one uses on the right: one makes the requirement non-trivial by forcing enough into the recursive specification so that one captures the native speaker’s implicit semantic competence. In this volume, the "orthodox" Davidsonian program, which takes the syntax of the metalanguage to be standard predicate logic, is ably argued by John Wallace ; Richard Montague, David Lewis, and Jaakko Hintikka would want an intensional logic covering modality and propositional attitudes. The linguists who find this philosophical climate most appealing are called "generative semanticists": McCawley, Ross, George Lakoff and others argue that any proposed semantic rule will eventually prove necessary to syntax too and that, hence, the deepest level of syntactical form will be equivalent to semantic form. Whatever the ultimate fate of this joint program, it leads here to much exciting interaction between linguists and philosophers: linguists who welcome the machinery and conceptual standards of modern logic, and philosophers who try to grasp the specifics of crucial issues in recent linguistic theory. Even if Quine’s doubts, here sketched, and Chomsky’s currently unpublished more technical objections should be well-founded, nonetheless the joint labor will have been very much worthwhile. Aside from this general debate about semantics, there are several papers covering more specific issues. The papers of J. A. Fodor, Terence Parsons, and Ross concern adverbs and the logical form of action sentences; several papers, particularly B. H. Partee’s, examine "Opacity, Coreference, and Pronouns." In all these papers one notes the fulfillment of Austin’s hope that philosophic and linguistic arguments should become intermixed, if not at times properly indistinguishable. Perhaps the most enjoyable and exciting paper stands aside from linguistics: Saul Kripke’s "Naming and Necessity." Kripke here argues quite informally for the separation of analytic, a priori, and necessary that is required for a Kripke style, S5, modal logic with de re modalities. "Gold is a yellow metal," for example, turns out to be contingent, while "Heat is the motion of particles" is necessary but a posteriori ; and that philosopher’s stone of stones, "The morning star is the evening star," is discovered to be necessary but a posteriori.—J. L. (shrink)

This paper is an edited form of a letter written by the two authors (in the name of Tarski) to Wolfram Schwabhäuser around 1978. It contains extended remarks about Tarski's system of foundations for Euclidean geometry, in particular its distinctive features, its historical evolution, the history of specific axioms, the questions of independence of axioms and primitive notions, and versions of the system suitable for the development of 1-dimensional geometry.

In this manuscript, published here for the first time, Tarski explores the concept of logical notion. He draws on Klein's Erlanger Programm to locate the logical notions of ordinary geometry as those invariant under all transformations of space. Generalizing, he explicates the concept of logical notion of an arbitrary discipline.

I ON THE PRIMITIVE TERM OF LOGISTICf IN this article I propose to establish a theorem belonging to logistic concerning some connexions, not widely known, ...

This article presents Tarski's Address at the Princeton Bicentennial Conference on Problems of Mathematics, together with a separate summary. Two accounts of the discussion which followed are also included. The central topic of the Address and of the discussion is decision problems. The introductory note gives information about the Conference, about the background of the subjects discussed in the Address, and about subsequent developments to these subjects.

This article presents Tarski's Address at the Princeton Bicentennial Conference on Problems of Mathematics, together with a separate summary. Two accounts of the discussion which followed are also included. The central topic of the Address and of the discussion is decision problems. The introductory note gives information about the Conference, about the background of the subjects discussed in the Address, and about subsequent developments to these subjects.

Published with the aid of a grant from the National Endowment for the Humanities. Contains the only complete English-language text of The Concept of Truth in Formalized Languages. Tarski made extensive corrections and revisions of the original translations for this edition, along with new historical remarks. It includes a new preface and a new analytical index for use by philosophers and linguists as well as by historians of mathematics and philosophy.

We provide for the first time an exact translation into English of the Polish version of Alfred Tarski's classic 1936 paper, whose title we translate as ?On the Concept of Following Logically?. We also provide in footnotes an exact translation of all respects in which the German version, used as the basis of the previously published and rather inexact English translation, differs from the Polish. Although the two versions are basically identical, to an extent that is even uncanny, we (...) note more than 400 differences. Several dozen of these are substantive differences due to revisions by Tarski to the Polish version which he did not incorporate in the German version. With respect to these revisions the Polish version should be regarded as more authoritative than the German. Hence scholars limited to an English translation should use ours. (shrink)

Published with the aid of a grant from the National Endowment for the Humanities. Contains the only complete English-language text of The Concept of Truth in Formalized Languages. Tarski made extensive corrections and revisions of the original translations for this edition, along with new historical remarks. It includes a new preface and a new analytical index for use by philosophers and linguists as well as by historians of mathematics and philosophy.

This book is well known for its proof that many mathematical systems - including lattice theory and closure algebras - are undecidable. It consists of three treatises from one of the greatest logicians of all time: "A General Method in Proofs of Undecidability," "Undecidability and Essential Undecidability in Mathematics," and "Undecidability of the Elementary Theory of Groups.".

This classic undergraduate treatment examines the deductive method in its first part and explores applications of logic and methodology in constructing mathematical theories in its second part. Exercises appear throughout.

Now in its fourth edition, this classic work clearly and concisely introduces the subject of logic and its applications. The first part of the book explains the basic concepts and principles which make up the elements of logic. The author demonstrates that these ideas are found in all branches of mathematics, and that logical laws are constantly applied in mathematical reasoning. The second part of the book shows the applications of logic in mathematical theory building with concrete examples that draw (...) upon the concepts and principles presented in the first section. Numerous exercises and an introduction to the theory of real numbers are also presented. Students, teachers and general readers interested in logic and mathematics will find this book to be an invaluable introduction to the subject. (shrink)

We provide for the first time an exact translation into English of the Polish version of Alfred Tarski's classic 1936 paper, whose title we translate as ‘On the Concept of Following Logically’. We also provide in footnotes an exact translation of all respects in which the German version, used as the basis of the previously published and rather inexact English translation, differs from the Polish. Although the two versions are basically identical, to an extent that is even uncanny, we (...) note more than 400 differences. Several dozen of these are substantive differences due to revisions by Tarski to the Polish version which he did not incorporate in the German version. With respect to these revisions the Polish version should be regarded as more authoritative than the German. Hence scholars limited to an English translation should use ours. (shrink)