This paper presents and defends a way to add a transparent truth predicate to classical logic, such that and A are everywhere intersubstitutable, where all T-biconditionals hold, and where truth can be made compositional. A key feature of our framework, called STTT (for Strict-Tolerant Transparent Truth), is that it supports a non-transitive relation of consequence. At the same time, it can be seen that the only failures of transitivity STTT allows for arise in paradoxical cases.

When discussing Logical Pluralism several critics argue that such an open-minded position is untenable. The key to this conclusion is that, given a number of widely accepted assumptions, the pluralist view collapses into Logical Monism. In this paper we show that the arguments usually employed to arrive at this conclusion do not work. The main reason for this is the existence of certain substructural logics which have the same set of valid inferences as Classical Logic—although they are, in a clear (...) sense, non-identical to it. We argue that this phenomenon can be generalized, given the existence of logics which coincide with Classical Logic regarding a number of metainferential levels—although they are, again, clearly different systems. We claim this highlights the need to arrive at a more refined version of the Collapse Argument, which we discuss at the end of the paper. (shrink)

According to the familiar Quinean understanding of ontological commitment, (1) one undertakes ontological commitments only via theoretical regimentations, and (2) ontological commitments are to be identified with the domain of a theory’s quantifiers. Jody Azzouni accepts (1), but rejects (2). Azzouni accepts (1) because he believes that no vernacular expression carries ontological commitments. He rejects (2) by locating a theory’s commitments with the extension of an existence predicate. I argue that Azzouni’s two theses undermine each other. If ontological commitments follow (...) from predications of existence, then ontological commitments can be expressed in the vernacular via negative existential sentences. (shrink)

In this paper we confront a challenge to truthmaker theory that is analogous to the objections raised by deflationists against substantive theories of truth. Several critics of truthmaker theory espouse a ‘deflationary’ attitude about truthmaking, though it has not been clearly presented as such. Our goal is to articulate and then object to the underlying rationale behind deflationary truthmaking. We begin by developing the analogy between deflationary truth and deflationary truthmaking, and then show how the latter can be found in (...) the work of Dodd, Hornsby, Schnieder, Williamson, and others. These philosophers believe that the ambitions of truthmaker theory are easily satisfied, without recourse to ambitious ontological investigation—hence the analogy with deflationary truth. We argue that the deflationists’ agenda fails: there is no coherent deflationary theory of truthmaking. Truthmaking, once deflated, fails to address the questions at the heart of truthmaking investigation. Truthmaking cannot be had on the cheap. (shrink)

Segundo um influente argumento contra a existência de conhecimento a priori, não há conhecimento a priori porque (i) nenhuma crença é imune à revisão, e (ii) se houvesse conhecimento a priori, algumas crenças seriam irrevisíveis. Uma versão deste argumento foi celebremente defendida por W. V. Quine e ainda é popular entre filósofos naturalistas. O objectivo deste artigo é examinar e rejeitar este argumento contra o a priori. O artigo começa por discutir a tese (i) e o seu papel no modelo (...) da Teia de Crenças de Quine. Defende-se que (i) enfrenta importantes desafios que colocam em risco o seu uso no argumento supra. A premissa (ii) do argumento é então discutida. Philip Kitcher é conhecido pela sua defesa de uma versão da premissa (ii). Os seus argumentos são analisados e rejeitados. A conclusão é que não temos uma boa razão para aceitar (ii), e consequentemente este argumento contra o a priori. O artigo termina com a proposta de uma caracterização do a priori perfeitamente compatível com (i). (shrink)

The paper seeks to answer two new questions about truth and scientific change: What lessons does the phenomenon of scientific change teach us about the nature of truth? What light do recent developments in the theory of truth, incorporating these lessons, throw on problems arising from the prevalence of scientific change, specifically, the problem of pessimistic meta-induction?

This paper extracts some of the main theses in the philosophy of mathematics from my book, The Construction of Logical Space. I show that there are important limits to the availability of nominalistic paraphrase functions for mathematical languages, and suggest a way around the problem by developing a method for specifying nominalistic contents without corresponding nominalistic paraphrases. Although much of the material in this paper is drawn from the book — and from an earlier paper — I hope the present (...) discussion will earn its keep by motivating the ideas in a new way, and by suggesting further applications. (shrink)

Michael Dummett, in ‘Truth,’ mounted an objection to the redundancy theory of truth on the grounds that it neglects to account for the normative features he claimed are part of the concept of truth. Paul Horwich, in ‘The Minimalist Conception of Truth’, notes that the same objection could be leveled against minimalism. He defends minimalism against Dummett’s objection by offering a sketch of an instrumental account of the desirability of truth that is compatible with the minimalist thesis. In this paper, (...) I will review Dummett’s objection and Horwich’s response, identifying some concerns with the account as it stands. I will modify the account to address those concerns, and so that it successfully explains the desirability of having all true beliefs in a way that is compatible with minimalism. I then mount an argument that truth is also intrinsically valuable. The question regarding the adequacy of the minimalist account of truth, then, hinges on whether the account is compatible with the fact of truth’s intrinsic value, along with the question of whether that fact entails its also being essentially valuable. (shrink)

There is no preferred reduction of number theory to set theory. Nonetheless, we confidently accept axioms obtained by substituting formulas from the language of set theory into the induction axiom schema. This is only possible, it is argued, because our acceptance of the induction axioms depends solely on the meanings of aritlunetical and logical terms, which is only possible if our 'intended models' of number theory are standard. Similarly, our acceptance of the second-order natural deduction rules depends solely on the (...) meanings of the logical terms, which implies, it is argued, that our second-order quantifiers have to be standard. (shrink)

According to the computational theory of mind , to think is to compute. But what is meant by the word 'compute'? The generally given answer is this: Every case of computing is a case of manipulating symbols, but not vice versa - a manipulation of symbols must be driven exclusively by the formal properties of those symbols if it is qualify as a computation. In this paper, I will present the following argument. Words like 'form' and 'formal' are ambiguous, as (...) they can refer to form in either the syntactic or the morphological sense. CTM fails on each disambiguation, and the arguments for CTM immediately cease to be compelling once we register that ambiguity. The terms 'mechanical' and 'automatic' are comparably ambiguous. Once these ambiguities are exposed, it turns out that there is no possibility of mechanizing thought, even if we confine ourselves to domains where all problems can be settled through decision-procedures. The impossibility of mechanizing thought thus has nothing to do with recherché mathematical theorems, such as those proven by Gödel and Rosser. A related point is that CTM involves, and is guilty of reinforcing, a misunderstanding of the concept of an algorithm. (shrink)

In this paper we investigate strong logics of first and second order that have certain absoluteness properties. We begin with an investigation of first order logic and the strong logics ω-logic and β-logic, isolating two facets of absoluteness, namely, generic invariance and faithfulness. It turns out that absoluteness is relative in the sense that stronger background assumptions secure greater degrees of absoluteness. Our aim is to investigate the hierarchies of strong logics of first and second order that are generically invariant (...) and faithful against the backdrop of the strongest large cardinal hypotheses. We show that there is a close correspondence between the two hierarchies and we characterize the strongest logic in each hierarchy. On the first-order side, this leads to a new presentation of Woodin's Ω-logic. On the second-order side, we compare the strongest logic with full second-order logic and argue that the comparison lends support to Quine's claim that second-order logic is really set theory in sheep's clothing. (shrink)

Minimalism is currently the received deflationary theory of truth. On minimalism, truth is a transparent concept and a deflated property of truth bearers. In this paper, I situate minimalism within current deflationary debate about truth by contrasting it with its main alternative―the redundancy theory of truth. I also outline three of the primary challenges facing minimalism, its formulation, explanatory adequacy and stability, and draw some lessons for the soundness of its conception of truth.

I examine various claims to the effect that Cantor's Continuum Hypothesis and other problems of higher set theory are ill-posed questions. The analysis takes into account the viability of the underlying philosophical views and recent mathematical developments.

A substitutional account of logical validity for formal first‐order languages is developed and defended against competing accounts such as the model‐theoretic definition of validity. Roughly, a substitution instance of a sentence is defined as the result of uniformly substituting nonlogical expressions in the sentence with expressions of the same grammatical category and possibly relativizing quantifiers. In particular, predicate symbols can be replaced with formulae possibly containing additional free variables. A sentence is defined to be logically true iff all its substitution (...) instances are satisfied by all variable assignments. Logical consequence is defined analogously. Satisfaction is taken to be a primitive notion and axiomatized.For every set‐theoretic model in the sense of model theory there exists a corresponding substitutional interpretation in a sense to be specified. Conversely, however, there are substitutional interpretations – in particular the ‘intended’ interpretation – that lack a model‐theoretic counterpart. The substitutional definition of logical validity overcomes the weaknesses of more restrictive accounts of substitutional validity; unlike model‐theoretic logical consequence, the substitutional notion is trivially and provably truth preserving. In Kreisel's squeezing argument the formal notion of substitutional validity naturally slots into the place of intuitive validity. (shrink)

Disquotational theories of truth, that is, theories of truth based on the T-sentences or similar equivalences as axioms are often thought to be deductively weak. This view is correct if the truth predicate is allowed to apply only to sentences not containing the truth predicate. By taking a slightly more liberal approach toward the paradoxes, I obtain a disquotational theory of truth that is proof theoretically as strong as compositional theories such as the Kripket probe the compositional axioms.

One might ask of two or more texts—what can be inferred from them, taken together? If the texts happen to contradict each other in some respect, then the unadorned answer of standard logic is EVERYTHING. But it seems to be a given that we often successfully reason with inconsistent information from multiple sources. The purpose of this paper is to attempt to develop an adequate approach to accounting for this given.

In this paper we discuss the difference between (...) proliferations of logic systems, the questions of relativity and universality of logic and the position and interaction of logic with regards to other sciences such as physics, biology, mathematics and computer science. (shrink)

To date, there is no universal and coherent theory concerning the nature or the function of time. Furthermore, important and unresolved controversies raging within both philosophy and the natural sciences apparently indicate that there is little hope of constructing a single, unified theory. Even so-called "folk" theories of time, embedded within different cultural traditions, show no common elements, and therefore can not provide a pre-theoretical description of time, towards which an explanatory framework could be constructed. This lack of consensus indicates (...) that the concept as it is currently being used is ill defined, and, at the very least, needs to be considerably revised. The conceptual disarray surrounding time has aided and abetted the arguments of certain thinkers, especially Ricoeur, working within the phenomenological tradition who make de principe claims that there can not be a single theory of time. My intention is not to try and to produce a concept of time that was capable of unifying all these different elements. Rather, Ricoeur's arguments and those of others working in the phenomenological tradition dissatisfied me. I believed that their arguments were informed by a myopic, muddled and positively 19th Century understanding of the scientific project. Hence, my aim is to show that Ricoeur's claim will not stand up to scrutiny, and that there are no principled arguments against the possibility of a unified theory of time. We examine the major arguments against unification in general, and also with particular reference to theories of time, such as Husserlian phenomenology, conventionalism, instrumentalism, anti-reductive positions in general, as well as the specific problem of reducing subjective experience to objective description. We demonstrate that none of these objections constitutes a watertight a priori argument against a unified theory of time. Furthermore, we demonstrate that recent developments in the philosophy of science and the philosophy of mind have made such a unified theory a plausible goal. We argue that post-positivist philosophy of science, with its emphasis on research programmes, the co-evolution of theories and super-empirical rational support, opens the way for new types of evidence to be brought to bear on questions about time. Also, recent developments in the brain sciences mean that a neurologically plausible and fully naturalised analysis of our experience of time is being developed. Although much work in this direction has begun, we argue that it is fragmented, partly through the limitations of our current knowledge, but more particularly through an inadequate background of coherent philosophical thought. This has lead both philosophers and scientists to attempt grand metaphysical answers to muddled philosophical questions which threaten the progress which natural science and the philosophy of science have offered in the second half of the twentieth century. (shrink)

This book is a contribution to the flourishing field of formal and philosophical work on truth and the semantic paradoxes. Our aim is to present several theories of truth, to investigate some of their model-theoretic, recursion-theoretic and proof-theoretic aspects, and to evaluate their philosophical significance. In Part I we first outline some motivations for studying formal theories of truth, fix some terminology, provide some background on Tarski’s and Kripke’s theories of truth, and then discuss the prospects of classical type-free truth. (...) In Chapter 4 we discuss some minimal adequacy conditions on a satisfactory theory of truth based on the function that the truth predicate is intended to fulfil on the deflationist account. We cast doubt on the adequacy of some non-classical theories of truth and argue in favor of classical theories of truth. Part II is devoted to grounded truth. In chapter 5 we introduce a game-theoretic semantics for Kripke’s theory of truth. Strategies in these games can be interpreted as reference-graphs of the sentences in question. Using that framework, we give a graph-theoretic analysis of the Kripke-paradoxical sentences. In chapter 6 we provide simultaneous axiomatizations of groundedness and truth, and analyze the proof-theoretic strength of the resulting theories. These range from conservative extensions of Peano arithmetic to theories that have the full strength of the impredicative system ID1. Part III investigates the relationship between truth and set-theoretic comprehen- sion. In chapter 7 we canonically associate extensions of the truth predicate with Henkin-models of second-order arithmetic. This relationship will be employed to determine the recursion-theoretic complexity of several theories of grounded truth and to show the consistency of the latter with principles of generalized induction. In chapter 8 it is shown that the sets definable over the standard model of the Tarskian hierarchy are exactly the hyperarithmetical sets. Finally, we try to apply a certain solution to the set-theoretic paradoxes to the case of truth, namely Quine’s idea of stratification. This will yield classical disquotational theories that interpret full second-order arithmetic without set parameters, Z2- . We also indicate a method to recover the parameters. An appendix provides some background on ordinal notations, recursion theory and graph theory. (shrink)