This is a contribution to the discussion on the role of truth degrees in manyvalued logics from the perspective of abstract algebraic logic. It starts with some thoughts on the so-called Suszko’s Thesis (that every logic is two-valued) and on the conception of semantics that underlies it, which includes the truth-preserving notion of consequence. The alternative usage of truth values in order to define logics that preserve degrees of truth is presented and discussed. Some recent works studying these in the (...) particular cases of Łukasiewicz’s many-valued logics and of logics associated with varieties of residuated lattices are also presented. Finally the extension of this paradigm to other, more general situations is discussed, highlighting the need for philosophical or applied motivations in the selection of the truth degrees, due both to the interpretation of the idea of truth degree and to some mathematical difficulties. (shrink)

Crispin Wright offers an original perspective on the place of “realism” in philosophical inquiry. He proposes a radically new framework for discussing the claims of the realists and the anti-realists. This framework rejects the classical “deflationary” conception of truth yet allows both disputants to respect the intuition that judgments, whose status they contest, are at least semantically fitted for truth and may often justifiably be regarded as true. In the course of his argument, Wright offers original critical discussions of many (...) central concerns of philosophers interested in realism, including the “deflationary” conception of truth, internal realist truth, scientific realism and the theoreticity of observation, and the role of moral states of affairs in explanations of moral beliefs. (shrink)

There have been few attempts to answer the twin challenges for alethic pluralists to maintain standard accounts of the logical operators and of logical consequence in a sufficiently systematic and precise way. In this paper, I propose an account of logic and semantics on behalf of pluralists that answers both challenges in a sufficiently systematic and precise way. Crucially, the account accommodates mixed atomics, and its first-order extension also accommodates quantified sentences. Accordingly, pluralists can answer all the distinctively logical challenges (...) for their view. (shrink)

Recasting important questions about truth and objectivity in new and helpful terms, his book will become a focus in the contemporary debates over realism, and ...

Every student of English-speaking analytical metaphysics is taught that the early twentieth century philosophical debate about truth confronted the correspondence theory, supported by Russell, Moore, the early Wittgenstein and, later, J.L. Austin, with the coherence theory advocated by the British Idealists. Sometimes the pragmatist conception of truth deriving from Dewey, William James, and C.S. Peirce is regarded as a third player. And as befits a debate at the dawn of analytical philosophy, the matter in dispute is normally taken to have (...) been the proper analysis of the concept.No doubt this conception nicely explains some of the characteristic turns taken in the debate. Analysis, as traditionally conceived, has to consist in the provision of illuminating conceptual equivalences; and illumination will depend, according to the standard rules of play, on the analysans’ utilizing only concepts which, in the best case, are in some way prior to and independent of the notion being analyzed — or, if that's too much to ask, then concepts which at least permit of some form of explication which does not in turn take one straight back to that notion. (shrink)

According to Suszko’s Thesis, there are but two logical values, true and false. In this paper, R. Suszko’s, G. Malinowski’s, and M. Tsuji’s analyses of logical twovaluedness are critically discussed. Another analysis is presented, which favors a notion of a logical system as encompassing possibly more than one consequence relation. [A] fundamental problem concerning many-valuedness is to know what it really is. [13, p. 281].

Mixed inferences are a problem for those who want to combine truth-assessability and antirealism with respect to allegedly nondescriptive sentences: the classical account of validity has apparently to be given up. J.C. Beall's response is that validity can be defined as the conservation of designated valued (Beall 2000). I argue that since it presupposes a truth predicate that can be applied to all sentences, this suggestion is not helpful. I also consider problems arising from mixed conjunctions and discuss the deeper (...) worry that the distinction between truth which does and truth which does not entail realism is inferentially irrelevant. (shrink)

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. (shrink)

Summary of the talk given to the 22nd Conference on the History of Logic, Cracow (Poland), July 5–9, 1976.

Alethic pluralism holds that there are many truth properties. The view has been challenged to make sense of the notion of logical validity, understood as necessary truth preservation, when inferences involving different areas of discourse are concerned. I argue that the solution proposed by Edwards to solve the analogous problem of mixed compounds can straightforwardly be adapted to give alethic pluralists also a viable account of validity.

Different formal tools are useful for different purposes. For example, when it comes to modelling degrees of belief, probability theory is a better tool than classical logic; when it comes to modelling the truth of mathematical claims, classical logic is a better tool than probability theory. In this paper I focus on a widely used formal tool and argue that it does not provide a good model of a phenomenon of which many think it does provide a good model: I (...) shall argue that while supervaluationism may provide a model of probability of truth, or of assertability, it cannot provide a good model of truth -- supertruth cannot be truth. The core of the argument is that an adequate model of truth must render certain connectives truth-functional (at least in certain circumstances) -- and supervaluationism does not do so (in those circumstances). (shrink)

We introduce several senses of the principle ofcompositionality. We illustrate the difference between them with thehelp of some recent results obtained by Cameron and Hodges oncompositional semantics for languages of imperfect information.

In the last few decades of the twentieth century there was a revolution in metaphysics: the intensional revolution. Many metaphysicians rejected the doctrine, associated with Quine and Davidson, that extensional analyses and theoretical resources were the only acceptable ones. Metaphysicians embraced tools like modal and counterfactual analyses, claims of modal and counterfactual dependence, and entities such as possible worlds and intensionally individuated properties and relations. The twenty-first century is seeing a hypterintensional revolution. Theoretical tools in common use carve more finely (...) than by necessary equivalence: two pieces of language can apply to the same entities across all possible worlds but not be equivalent; thoughts can be necessarily equivalent in truth value but not synonymous. This paper argues that hyperintensional resources are valuable in metaphysics outside theories of representation, and discusses some promising areas of hyperintensional metaphysics. (shrink)

What is truth? Michael Lynch defends a bold new answer to this question. Traditional theories of truth hold that truth has only a single uniform nature. All truths are true in the same way. More recent deflationary theories claim that truth has no nature at all; the concept of truth is of no real philosophical importance. In this concise and clearly written book, Lynch argues that we should reject both these extremes and hold that truth is a functional property. To (...) understand truth we must understand what it does, its function in our cognitive economy. Once we understand that, we'll see that this function can be performed in more than one way. And that in turn opens the door to an appealing pluralism: beliefs about the concrete physical world needn't be true in the same way as our thoughts about matters -- like morality -- where the human stain is deepest. (shrink)

In Truth as One and Many, Michael Lynch offers a new theory of truth. There are two kinds of theory of truth in the literature. On the one hand, we have logical theories, which seek to construct formal systems that are consistent, while also containing a predicate which have as many as possible of the properties which we ordinarily take the English predicate ‘is true’ to have; salient examples include Tarski’s and Kripke’s theories of truth. On the other hand, we (...) have metaphysical theories, which seek to give a non-formal account of the nature of truth – of what truth consists in, of what it means to say that something is true; salient examples include correspondence, coherence and deflationary theories of truth. Lynch’s theory – functionalism about truth – is of the second sort.The theory takes its start from a number of principles which Lynch classifies as truisms about truth:Objectivity: The belief that p is true if, and only if, with respect to the belief that p, things are as they are believed to be.Norm of Belief: It is prima facie correct to believe that p if and only if the proposition that p is true.End of Inquiry: Other things being equal, true beliefs are a worthy goal of inquiry.Lynch argues that other familiar principles can be derived from these: for example, Objectivity together with some auxiliary principles and definitions yields versions of the T-schema, and of the principle that beliefs can be true without being warranted and vice versa. These principles are supposed to give the nominal essence of truth – to constitute our folk theory of truth. Lynch …. (shrink)

We describe a logic which is the same as first-order logic except that it allows control over the information that passes down from formulas to subformulas. For example the logic is adequate to express branching quantifiers. We describe a compositional semantics for this logic; in particular this gives a compositional meaning to formulas of the 'information-friendly' language of Hintikka and Sandu. For first-order formulas the semantics reduces to Tarski's semantics for first-order logic. We prove that two formulas have the same (...) interpretation in all structures if and only if replacing an occurrence of one by an occurrence of the other in a sentence never alters the truth-value of the sentence in any structure. (shrink)

Monists say that the nature of truth is invariant, whichever sentence you consider; pluralists say that the nature of truth varies between different sets of sentences. The orthodoxy is that logic and logical form favour monism: there must be a single property that is preserved in any valid inference; and any truth-functional complex must be true in the same way as its components. The orthodoxy, I argue, is mistaken. Logic and logical form impose only structural constraints on a metaphysics of (...) truth. Monistic theories are not guaranteed to satisfy these constraints, and there is a pluralistic theory that does so. (shrink)

ABSTRACTEcumenical Alethic Pluralism is a novel kind of alethic pluralism. It is ecumenical in that it widens the scope of alethic pluralism by allowing for a normatively deflated truth property alongside a variety of normatively robust truth properties. We establish EAP by showing how Wright’s Inflationary Arguments fail in the domain of taste, once a relativist treatment of the metaphysics and epistemology of that domain is endorsed. EAP is highly significant to current debates on the nature of truth insofar as (...) it involves a reconfiguration of the dialectic between deflationists and pluralists. (shrink)

In Truth and Objectivity, Crispin Wright argues that because truth is a distinctively normative property, it cannot be as metaphysically insubstantive as deflationists claim.1 This argument has been taken, together with the scope problem,2 as one of the main motivations for alethic pluralism.3 We offer a reconstruction of Wright’s Inflationary Argument (henceforth IA) aimed at highlighting what are the steps required to establish its inflationary conclusion. We argue that if a certain metaphysical and epistemological view of a given subject matter (...) is accepted, a local counterexample to IA can be constructed. We focus on the domain of basic taste and we develop two variants of a subjectivist and relativist metaphysics and epistemology that seems palatable in that domain. Although we undertake no commitment to this being the right metaphysical cum epistemological package for basic taste, we contend that if the metaphysics and the epistemology of basic taste are understood along these lines, they call for a truth property whose nature is not distinctively normative—contra what IA predicts. This result shows that the success of IA requires certain substantial metaphysical and epistemological principles and that, consequently, a proper assessment of IA cannot avoid taking a stance on the metaphysics and the epistemology of the domain where it is claimed to be successful. Although we conjecture that IA might succeed in other domains, in this paper we don’t take a stand on this issue. We conclude by briefly discussing the significance of this result for the debate on alethic pluralism. (shrink)

In Truth and Objectivity, Crispin Wright argues that because truth is a distinctively normative property, it cannot be as metaphysically insubstantive as deflationists claim. We offer a reconstruction of Wright’s Inflationary Argument that highlights the steps required to establish its inflationary conclusion. We argue that if a certain metaphysical and epistemological view of a given subject matter is accepted, a local counterexample to the Inflationary Argument can be constructed. As a case study we focus on the domain of basic taste. (...) We develop two variants of a subjectivist and relativist metaphysics and epistemology that seem palatable in that domain and we show that the Inflationary Argument doesn’t go through in the domain of basic taste thus construed. We conclude by briefly discussing the significance of this result for the debate on alethic pluralism. (shrink)

Michael Dummett; VIII.—Truth, Proceedings of the Aristotelian Society, Volume 59, Issue 1, 1 June 1959, Pages 141–162, https://doi.org/10.1093/aristotelian/59.1.

Michael Dummett; VIII.—Truth, Proceedings of the Aristotelian Society, Volume 59, Issue 1, 1 June 1959, Pages 141–162, https://doi.org/10.1093/aristotelian/59.1.

Michael Dummett; VIII.—Truth, Proceedings of the Aristotelian Society, Volume 59, Issue 1, 1 June 1959, Pages 141–162, https://doi.org/10.1093/aristotelian/59.1.

Suszko’s problem is the problem of finding the minimal number of truth values needed to semantically characterize a syntactic consequence relation. Suszko proved that every Tarskian consequence relation can be characterized using only two truth values. Malinowski showed that this number can equal three if some of Tarski’s structural constraints are relaxed. By so doing, Malinowski introduced a case of so-called mixed consequence, allowing the notion of a designated value to vary between the premises and the conclusions of an argument. (...) In this article we give a more systematic perspective on Suszko’s problem and on mixed consequence. First, we prove general representation theorems relating structural properties of a consequence relation to their semantic interpretation, uncovering the semantic counterpart of substitution-invariance, and establishing that mixed consequence is fundamentally the semantic counterpart of the structural property of monotonicity. We use those theorems to derive maximum-rank results proved recently in a different setting by French and Ripley, as well as by Blasio, Marcos, and Wansing, for logics with various structural properties. We strengthen these results into exact rank results for nonpermeable logics. We discuss the underlying notion of rank, and the associated reduction proposed independently by Scott and Suszko. As emphasized by Suszko, that reduction fails to preserve compositionality in general, meaning that the resulting semantics is no longer truth-functional. We propose a modification of that notion of reduction, allowing us to prove that over compact logics with what we call regular connectives, rank results are maintained even if we request the preservation of truth-functionality and additional semantic properties. (shrink)

Jenkins (2007) charges that the language advanced in Beall (2007) is either expressively impoverished, or inconsistent. We argue that Jenkins’ objections are based on unreasonably strong constraints on formal theories of truth. Our primary concern is not to defend the ‘paranormal’ framework advanced in Beall, but to respond to a common – and implausible – ‘revenge’-style charge directed at a certain class of formal theories of truth and paradox.

This book provides an incisive, basic introduction to many-valued logics and to the constructions that are "many-valued" at their origin. Using the matrix method, the author sheds light on the profound problems of many-valuedness criteria and its classical characterizations. The book also includes information concerning the main systems of many-valued logic, related axiomatic constructions, and conceptions inspired by many-valuedness. With its selective bibliography and many useful historical references, this book provides logicians, computer scientists, philosophers, and mathematicians with a valuable survey (...) of the subject. (shrink)

Central to any form of Deflationism concerning truth (hereafter ‘DT’) is the claim that truth has no substantial theoretical role to play. For this reason, DT faces the following immediate challenge: if truth can play no substantial theoretical role then how can we model various prevalent kinds of indeterminacy—such as the indeterminacy exhibited by vague predicates, future contingents, liar sentences, truth-teller sentences, incomplete stipulations, cases of presupposition failure, and such-like? It is too hasty to assume that these phenomena are all (...) to be modelled via some epistemic conception of indeterminacy whereby indeterminacy is just some special species of ignorance which arises because of our limited powers of discrimination. Some non-epistemic model is called for—at least for certain species of indeterminacy. On what is perhaps the most enduring and popular non-epistemic model, indeterminacy gives rise to truth-value gaps. But is DT compatible with the possibility of truth-value gaps? Compatibilism says Yes; Incompatibilism says No. The broad goal of this paper is to defend a form of Incompatibilism. If DT is to make sense of various kinds of indeterminacy then truth-value gaps cannot be invoked to do so. The particular goals of this paper are: (i) To set forth a new form of Compatibilism which can address an argument against truth-value gaps given by Williamson (1994, pp. 187-192). (ii) To offer a new argument against truth-value gaps using principles entailed by DT, thereby undermining Compatibilism. (shrink)

Alethic pluralism holds that there are many ways of being true. Such a view has been challenged to make sense of the standard account of logical validity as necessary truth preservation. In this paper, the recent solution elaborated by Aaron Cotnoir, based on an algebraic approach, is shown to be untenable. Some reflections about the relation of many-valued logics with truth pluralism are also discussed.

The challenge for alethic pluralists to maintain a standard, truth-functional account of the logical operators has received some attention. In this paper, I consider a related but more fundamental challenge, to maintain a compositional account of the logical operators, which has received much less attention. I argue that, given natural assumptions, pluralists cannot answer this challenge.