Buridan's Solution to the Liar Paradox

Jean Buridan has offered a solution to the Liar Paradox, i.e. to the problem of assigning a truth-value to the sentence ‘What I am saying is false’. It has been argued that either (1) this solution is ad hoc since it would only apply to self-referencing sentences [Read, S. 2002. ‘The Liar Paradox from John Buridan back to Thomas Bradwardine’, Vivarium, 40 (2), 189–218] or else (2) it weakens his theory of truth, making his ‘a logic without truth’ [Klima, G. 2008. ‘Logic without truth: Buridan on the Liar’, in S. Rahman, T. Tulenheimo and E. Genot, Unity, Truth and the Liar: The Modern Relevance of Medieval Solutions to the Liar Paradox, Berlin: Springer, 87–112 (Chapter 5); Dutilh Novaes, C. 2011. ‘Lessons on truth from mediaeval solutions to the Liar Paradox’, The Philosophical Quarterly, 61 (242), 58–78]. Against (1), I will argue that Buridan's solution by means of truth by supposition does not involve new principles. Self-referential sentences force us to handle supposition more carefully, which does not warrant the accusation of adhoccery. I will also argue, against (2), that it is exaggerated to assert that this solution leads to a ‘weakened’ theory of truth, since it is consistent with other passages of the Sophismata, which only gives necessary conditions for the truth of affirmative propositions, but sufficient conditions for falsity.     

Alethic fictionalism,alethic nihilism,and the Liar Paradox

Recently, several philosophers have proposed fictionalist accounts of truth-talk, as a means for resolving the semantic pathology that the Liar Paradox appears to present. These alethic fictionalists aim to vindicate truth-talk as a kind of as if discourse, while rejecting that the talk attributes any real property of truth. Liggins (Analysis 74:566–574, 2014) has recently critically assessed one such proposal, Beall’s (The law of non-contradiction: new philosophical essays. Oxford University Press, New York, pp 197–216, 2004) constructive methodological deflationist (henceforth, ‘CMD’), offering objections to Beall’s proposed alethic fictionalism that potentially generalize to other alethic fictionalist accounts. Liggins further argues that CMD supports a classically consistent response to the Liar Paradox—one that can be extracted from CMD, while leaving its putatively problematic fictionalist elements behind in favor of alethic nihilism. In this paper, after establishing that Liggins’s criticisms of CMD are off base, we show that the classical resolution of the Liar Paradox that he proposes is unworkable. Since his resistance to alethic fictionalism turns out to be unmotivated, we conclude that this approach is still worth considering as a framework for a resolution of the Liar Paradox.     

Moore's Paradox and Epistemic Norms

We shall evaluate two strategies for motivating the view that knowledge is the norm of belief. The first draws on observations concerning belief's aim and the parallels between belief and assertion. The second appeals to observations concerning Moore's Paradox. Neither of these strategies gives us good reason to accept the knowledge account. The considerations offered in support of this account motivate only the weaker account on which truth is the fundamental norm of belief.     

Paradoxical hypodoxes

Synthese - Most paradoxes of self-reference have a dual or ‘hypodox’. The Liar paradox (Lr = ‘Lr is false’) has the Truth-Teller (Tt = ‘Tt is true’)....     

Field's Paradox and Its Medieval Solution

Hartry Field's revised logic for the theory of truth in his new book, Saving Truth from Paradox, seeking to preserve Tarski's T-scheme, does not admit a full theory of negation. In response, Crispin Wright proposed that the negation of a proposition is the proposition saying that some proposition inconsistent with the first is true. For this to work, we have to show that this proposition is entailed by any proposition incompatible with the first, that is, that it is the weakest proposition incompatible with the proposition whose negation it should be. To show that his proposal gave a full intuitionist theory of negation, Wright appealed to two principles, about incompatibility and entailment, and using them Field formulated a paradox of validity (or more precisely, of inconsistency).

The medieval mathematician, theologian and logician, Thomas Bradwardine, writing in the fourteenth century, proposed a solution to the paradoxes of truth which does not require any revision of logic. The key principle behind Bradwardine's solution is a pluralist doctrine of meaning, or signification, that propositions can mean more than they explicitly say. In particular, he proposed that signification is closed under entailment. In light of this, Bradwardine revised the truth-rules, in particular, refining the T-scheme, so that a proposition is true only if everything that it signifies obtains. Thereby, he was able to show that any proposition which signifies that it itself is false, also signifies that it is true, and consequently is false and not true. I show that Bradwardine's solution is also able to deal with Field's paradox and others of a similar nature. Hence Field's logical revisions are unnecessary to save truth from paradox.     

Grelling’s Paradox

Grelling’s Paradox is the paradox which results from considering whether heterologicality, the word-property which a designator has when and only when the designator does not bear the word-property it designates, is had by ‘ ȁ8heterologicality’. Although there has been some philosophical debate over its solution, Grelling’s Paradox is nearly uniformly treated as a variant of either the Liar Paradox or Russell’s Paradox, a paradox which does not present any philosophical challenges not already presented by the two better known paradoxes. The aims of this paper are, first, to offer a precise formulation of Grelling’s Paradox which is clearly distinguished from both the Liar Paradox and Russell’s Paradox; second, to offer a solution to Grelling’s Paradox which both resolves the paradoxical reasoning and accounts for unproblematic predications of heterologicality; and, third, to argue that there are two lessons to be drawn from Grelling’s Paradox which have not yet been drawn from the Liar or Russell’s Paradox. The first lesson is that it is possible for the semantic content of a predicate to be sensitive to the semantic context; i.e., it is possible for a predicate to be an indexical expression. The second lesson is that the semantic content of an indexical predicate, though unproblematic for many cases, can nevertheless be problematic in some cases.     

Idealism and Williams's Semantic Paradox

Bernard Williams's essay ‘Wittgenstein and Idealism’ argues that that the conventionality of language entails the dependence of the truth of sentences and ultimately of corresponding states of affairs as truth‐makers on the existence of thinking subjects. Peter Winch and Colin Lyas try to avoid William's paradox by distinguishing between the existence conditions of a sentence and its assertion. The Winch‐Lyas solution is criticized and a stronger Winch‐Lays resistant version of Williams's paradox is proposed. A more satisfactory countercriticism is given, involving an ineliminable modal fallacy occurring in the paradox inference, that arises because of the argument's invalid combination of categorical and counterfactual assumptions and conclusions.     

Right and Righteous: Children's Incipient Understanding and Evaluation of True and False Statements

Two studies examined young children's early understanding and evaluation of truth telling and lying and the role that factuality plays in their judgments. Study 1 (one hundred four 2- to 5-year-olds) found that even the youngest children reliably accepted true statements and rejected false statements and that older children's ability to label true and false (T/F) statements as “truth” and “lie” emerged in tandem with their positive evaluation of true statements and “truth” and their negative evaluation of false statements and “lie.” The findings suggest that children's early preference for factuality develops into a conception of “truth” and “lie” that is linked both to factuality and moral evaluation. Study 2 (one hundred twenty-eight 3- to 5-year-olds) revealed that whereas young children exhibited good understanding of the association of T/F statements with “truth,” “lie,” “mistake,” “right,” and “wrong,” they showed little awareness of assumptions about speaker knowledge underlying “lie” and “mistake.” The results further support the primacy of factuality in children's early understanding and evaluation of truth and lies.     

IS METAPHYSICAL NIHILISM INTERESTING?

Suppose nothing exists. Then it is true that nothing exists. What makes that true? Nothing! So it seems that if nothing existed, then the principle that every truth is made true by something (the truthmaker principle) would be false. So if it is possible that nothing exists, a claim often called ‘metaphysical nihilism’, then the truthmaker principle is not necessary. This paper explores various ways to resolve this conflict without restricting metaphysical nihilism in such a way that it would become trivial and uninteresting.     

The Paradox of Belief Instability and a Revision Theory of Belief

The epistemic paradox of 'belief instability' has recently received notable attention from many philosophers. In this paper I offer a new proposal, which I call a 'revision theory of belief'. This theory is in many respects an application of Gupta's and Belnap's revision theory of truth. They argue that the Liar paradox arises because our notion of truth is circular. I offer a similar proposal for handling the paradox of belief instability. In particular, I argue that our notion involved in the paradox of belief instability is circular, and this circularity of belief is the source of the paradox.     

Minimalism and Paradoxes

This paper argues against minimalism about truth. It does so by way of acomparison of the theory of truth with the theory of sets, and considerationof where paradoxes may arise in each. The paper proceeds by asking twoseemingly unrelated questions. First, what is the theory of truth about?Answering this question shows that minimalism bears important similaritiesto naive set theory. Second, why is there no strengthened version ofRussell's paradox, as there is a strengthened Liar paradox? Answering thisquestion shows that like naive set theory, minimalism is unable to makeadequate progress in resolving the paradoxes, and must be replaced by adrastically different sort of theory. Such a theory, it is shown, must befundamentally non-minimalist.     

Truth,Predication and a Family of Contingent Paradoxes

In truth theory one aims at general formal laws governing the attribution of truth to statements. Gupta’s and Belnap’s revision-theoretic approach provides various well-motivated theories of truth, in particular T* and T#, which tame the Liar and related paradoxes without a Tarskian hierarchy of languages. In property theory, one similarly aims at general formal laws governing the predication of properties. To avoid Russell’s paradox in this area a recourse to type theory is still popular, as testified by recent work in formal metaphysics by Williamson and Hale. There is a contingent Liar that has been taken to be a problem for type theory. But this is because this Liar has been presented without an explicit recourse to a truth predicate. Thus, type theory could avoid this paradox by incorporating such a predicate and accepting an appropriate theory of truth. There is however a contingent paradox of predication that more clearly undermines the viability of type theory. It is then suggested that a type-free property theory is a better option. One can pursue it, by generalizing the revision-theoretic approach to predication, as it has been done by Orilia with his system P*, based on T*. Although Gupta and Belnap do not explicitly declare a preference for T# over T*, they show that the latter has some advantages, such as the recovery of intuitively acceptable principles concerning truth and a better reconstruction of informal arguments involving this notion. A type-free system based on T# rather than T* extends these advantages to predication and thus fares better than P* in the intended applications of property theory.

     

说谎者悖论及其相关悖论的一种解决

依本文之见,说谎者悖论以及某些与之相关的悖论之被导出源于对某些不合理的前提的接受;而这些前提之被接受又源于对＂是真的＂与＂是假的＂这两个词的关键语义特性缺乏认识。本文为决定这些语义特性的基础提供了说明;这一基础包含两个论点,第一,每一语句均有其含义;第二,每一语句陈说的字面内容是一个命题态度的内容,因而具有某种一般形式。借助于这一基础,本文为这两个词构造了一个不同于传统意义上的塔尔斯基式真理理论的意义理论以说明这些特性,并借助于该理论论证说谎者悖论及其某些相关悖论的导出没有根据。     

The reality of absences

In this paper, I make a contribution to a naturalistically-minded theory of truthmakers by proposing a solution to the nasty problem of truthmakers for negative truths. After formulating the difficulty, I consider and reject a number of solutions to the problem, including Armstrong's states of affairs of totality, incompatibility accounts, and JC Beall's polarity view. I then defend the position that absences of truthmakers are real and are responsible for making negative truths true (and positive falsehoods false). According to the positive account of absences I offer, absences of contingent states of affairs are causally relevant mind-independent features of the physical world, located within space and time, and capable of being discovered by scientific inquiry. Recognition of the reality of absences strengthens truthmaker theory as a naturalistic metaphysics, as truth and falsity of each and every contingent proposition finds an ontological grounding in some region of the physical universe.     

The Byzantine Liar

An eleventh-century Greek text, in which a fourth-century patristic text is discussed, gives an outline of a solution to the Liar Paradox. The eleventh-century text is probably the first medieval treatment of the Liar. Long passages from both texts are translated in this article. The solution to the Liar Paradox, which they entail, is analysed and compared with the results of modern scholarship on several Latin solutions to this paradox. It is found to be a solution, which bears some analogies to contemporary game semantics. Further, an overview of other Byzantine scholia on the Liar Paradox is provided. The findings and the originality of the discussed solution to the Liar Paradox suggest a change in the way in which Byzantine Logic is traditionally regarded in contemporary scholarship.     

On a medieval solution to the liar paradox

In this paper, I examine a solution to the Liar paradox found in the work of Ockham, Burley, and Pseudo-Sherwood. I reject the accounts of this solution offered by modern commentators. I argue that this medieval line suggests a non-hierarchical solution to the Liar, according to which ‘true’ is analysed as an indexical term, and paradox is avoided by minimal restrictions on tokens of ‘true’. In certain respects, this solution resembles the recent approaches of Charles Parsons and Tyler Burge; in other respects, it is related to a suggestion of Gödel. But, as a whole, it suggests an original solution to the Liar paradox, quite unlike any current proposals.     

Moore's Paradox and Akratic Belief

G.E. Moore noticed the oddity of statements like: “It's raining, but I don't believe it.” This oddity is often seen as analogous to the oddity of believing akratically, or believing what one believes one should not believe, and has been appealed to in denying the possibility of akratic belief. I describe a Belief Akratic's Paradox, analogous to Moore's paradox and centered on sentences such as: “I believe it's raining, but I shouldn't believe it.” I then defend the possibility of akratic belief against appeals to this analogy, arguing both that akratic belief does not require belief‐akratic‐paradoxical belief, and that the latter is importantly different from Moorean belief. I conclude by considering the implications of these arguments for an understanding of both Moorean and akratic belief.     

A Contextual-Hierarchical Approach to Truth and the Liar Paradox

This paper presents an approach to truth and the Liar paradox which combines elements of context dependence and hierarchy. This approach is developed formally, using the techniques of model theory in admissible sets. Special attention is paid to showing how starting with some ideas about context drawn from linguistics and philosophy of language, we can see the Liar sentence to be context dependent. Once this context dependence is properly understood, it is argued, a hierarchical structure emerges which is neither ad hoc nor unnatural.     

Number words and reference to numbers

A realist view of numbers often rests on the following thesis: statements like ‘The number of moons of Jupiter is four’ are identity statements in which the copula is flanked by singular terms whose semantic function consists in referring to a number (henceforth: Identity). On the basis of Identity the realists argue that the assertive use of such statements commits us to numbers. Recently, some anti-realists have disputed this argument. According to them, Identity is false, and, thus, we may deny that the relevant statements commit us to numbers. The present paper argues that the correct linguistic analysis of the relevant number statements supports the anti-realist view that Identity is false. However, as will further be shown, pace the anti-realist, this analysis does not establish that such statements do not commit us to numbers after all.     

Negative truths and truthmaker principles

This paper argues that a consideration of the problem of providing truthmakers for negative truths undermines truthmaker theory. Truthmaker theorists are presented with an uncomfortable dilemma. Either they must take up the challenge of providing truthmakers for negative truths, or else they must explain why negative truths are exceptions to the principle that every truth must have a truthmaker. The first horn is unattractive since the prospects of providing truthmakers for negative truths do not look good neither absences, nor totality states of affairs, nor Graham Priest and J.C. Beall’s ‘polarities’ (Beall, 2000; Priest, 2000) are up to the job. The second horn, meanwhile, is problematic because restricting the truthmaker principle to atomic truths, or weakening it to the thesis that truth supervenes on being, undercuts truthmaker theory’s original motivation. The paper ends by arguing that truthmaker theory is, in any case, an under-motivated doctrine because the groundedness of truth can be explained without appeal to the truthmaker principle. This leaves us free to give the ommonsensical and deflationary explanation of negative truths that common-sense suggests.