The paper contains a short story which is inconsistent, essentially so, but perfectly intelligible. The existence of such a story is used to establish various views about truth in fiction and impossible worlds.

In Contradiction advocates and defends the view that there are true contradictions, a view that flies in the face of orthodoxy in Western philosophy since Aristotle. The book has been at the center of the controversies surrounding dialetheism ever since its first publication in 1987. This second edition of the book substantially expands upon the original in various ways, and also contains the author’s reflections on developments over the last two decades. Further aspects of dialetheism are discussed in the companion (...) volume, Doubt Truth to be a Liar, also published by Oxford University Press in 2006. (shrink)

The paper is a discussion of a result of Hilbert and Bernays in their Grundlagen der Mathemnatik. Their interpretation of the result is similar to the standard intepretation of Tarski's Theorem. This and other interpretations are discussed and shown to be inadequate. Instead, it is argued, the result refutes certain versions of Meinongianism. In addition, it poses new problems for classical logic that are solved by dialetheism.

Dialetheism is the view that some contradictions are true. This is a view which runs against orthodoxy in logic and metaphysics since Aristotle, and has implications for many of the core notions of philosophy. Doubt Truth to Be a Liar explores these implications for truth, rationality, negation, and the nature of logic, and develops further the defense of dialetheism first mounted in Priest's In Contradiction, a second edition of which is also available.

The paper concerns time, change and contradiction, and is in three parts. The first is an analysis of the problem of the instant of change. It is argued that some changes are such that at the instant of change the system is in both the prior and the posterior state. In particular there are some changes from p being true to p being true where a contradiction is realized. The second part of the paper specifies a formal logic which accommodates (...) this possibility. It is a tense logic based on an underlying paraconsistent prepositional logic, the logic of paradox. (See the author's article of the same name Journal of Philosophical Logic 8 (1979).) Soundness and completeness are established, the latter by the canonical model construction, and extensions of the basic system briefly considered. The final part of the paper discusses Leibniz's principle of continuity: Whatever holds up to the limit holds at the limit. It argues that in the context of physical changes this is a very plausible principle. When it is built into the logic of the previous part, it allows a rigorous proof that change entails contradictions. Finally the relation of this to remarks on dialectics by Hegel and Engels is briefly discussed. (shrink)

The paper discusses the similarity between geometry, arithmetic, and logic, specifically with respect to the question of whether applied theories of each may be revised. It argues that they can - even when the revised logic is a paraconsistent one, or the revised arithmetic is an inconsistent one. Indeed, in the case of logic, it argues that logic is not only revisable, but, during its history, it has been revised. The paper also discusses Quine's well known argument against the possibility (...) of logical deviancy. (shrink)

This is a philosophical investigation of the nature of the limits of thought. Drawing on recent developments in the field of logic, Graham Priest shows that the description of such limits leads to contradiction, and argues that these contradictions are in fact veridical. Beginning with an analysis of the way in which these limits arise in pre-Kantian philosophy, Priest goes on to illustrate how the nature of these limits was theorised by Kant and Hegel. He offers new interpretations (...) of Berkeley's master argument for idealism and Kant on the antimonies. He explores the paradoxes of self reference, and provides a unified account of the structure of such paradoxes. The book concludes by tracing the theme of the limits of thought in modern philosophy of language, including discussions of the ideas of Wittgenstein and Derrida. (shrink)

The paper discusses the similarity between geometry, arithmetic, and logic, specifically with respect to the question of whether applied theories of each may be revised. It argues that they can - even when the revised logic is a paraconsistent one, or the revised arithmetic is an inconsistent one. Indeed, in the case of logic, it argues that logic is not only revisable, but, during its history, it has been revised. The paper also discusses Quine's well known argument against the possibility (...) of “logical deviancy”. (shrink)

Published in the American Journal of Bioethics.

A counterpossible conditional is a counterfactual with an impossible antecedent. Common sense delivers the view that some such conditionals are true, and some are false. In recent publications, Timothy Williamson has defended the view that all are true. In this paper we defend the common sense view against Williamson’s objections.

This paper is about the ?Imaginary Logic? developed by the Russian logician Nicholas Vasil'év between about 1910 and 1913, a logic that is often claimed to be a forerunner of different sorts of modern nonclassical logics. The paper describes the content of that logic (not by trying to interpret it in modern logic, as some commentators have done, but by describing it in its own terms). It then looks at the philosophical underpinnings of the logic. Finally, in the light of (...) the preceding, it discusses Vasil?év's place in the history of logic. (shrink)

The Law of Non-Contradiction - that no contradiction can be true - has been a seemingly unassailable dogma since the work of Aristotle, in Book G of the Metaphysics. It is an assumption challenged from a variety of angles in this collection of original papers. Twenty-three of the world's leading experts investigate the 'law', considering arguments for and against it and discussing methodological issues that arise whenever we question the legitimacy of logical principles. The result is a balanced inquiry into (...) a venerable principle of logic, one that raises questions at the very centre of logic itself. The aim of this volume is to present a comprehensive debate about the Law of Non-Contradiction, from discussions as to how the law is to be understood, to reasons for accepting or re-thinking the law, and to issues that raise challenges to the law, such as the Liar Paradox, and a 'dialetheic' resolution of that paradox. The editors contribute an introduction which surveys the issues and serves to frame the debate, and a useful bibliography offering a guide to further reading. This volume will be of interest to anyone working on philosophical logic, and to anyone who has ever wondered about the status of logical laws and about how one might proceed to mount arguments for or against them. (shrink)

Honderich claims that for a person to be perceptually conscious is for a world to exist. I decide what this means, and whether it could be true, in the opening section Consciousness and Existence. In Honderich's Phenomenology, I show that Honderich's theory is essentially anticipated in the ideas and Ideas of Husserl. In the third section, Radical Interiority, I argue that although phenomenology putatively eschews ontology of mind, and Honderich construes his position as near- physicalism, Honderich's insights are only truths (...) because we are spiritual substances. (shrink)

When a wrongdoing occurs, victims, barring special circumstance, can aptly forgive their wrongdoers, receive apologies, and be paid reparations. It is also uncontroversial, in the usual circumstances, that wronged parties can aptly blame their wrongdoer. But controversy arises when we consider blame from third-parties after the victim has forgiven. At times it seems that wronged parties can make blame inapt through forgiveness. If third parties blame anyway, it often appears the victim is justified in protesting. “But I forgave him!” In (...) other cases, however, forgiveness seems irrelevant: B can forgive A, but it can still seem that third parties can aptly blame A for the wrong against B. This perplexity adds a dimension to ongoing discussion regarding criteria for apt blame and the related issues of standing and fittingness. This paper explores the status of third party blame after forgiveness. I argue that while post forgiveness blame is often inapt, in many other cases forgiveness is irrelevant. This difference is explained by appeal to the various relationships third parties might have to wronged parties, and how these differences affect the ways we blame and thereby blame’s aptness. (shrink)

IntroductionCurry’s paradox is well known.See, e.g., Priest , ch. 6. It comes in both set theoretic and semantic versions. Here we will concentrate on the semantic versions. Historically, these have deployed the notion of truth. Those who wish to endorse an unrestricted T-schema have mainly endorsed a logic which rejects the principle of Absorption, \\models A\rightarrow B\). High profile logics of this kind are certain relevant logics; these have semantics which show how and why this principle is not valid. (...) Of more recent times, paradoxes which are clearly in the same family have been appearing; but these concern the notion of validity itself. The standard semantics of relevant logics seem powerless to address these. But they can. This note shows how. The upshot can be seen as a return to the roots of relevant logic, in a sense to become clear.BackgroundThe Usual Curry ParadoxesLet us start with a couple of standard forms of the paradox. I .. (shrink)

Despite the rapid growth of interest in Hegel among English-speaking philosophers, surprisingly little has been directed at Hegel's relationship toward Kant. This collection of essays by eleven eminent philosophers meets this deficiency by critically examining Hegel's attitude to Kant over a wide range of issues: the nature of space and time; the possibility of metaphysics, categories, and things-in-themselves; dialectic and the self; moral and political philosophy; aesthetics; the philosophy of history, and teleology. All the essays provide channels to a fuller (...) understanding of the forks of theoretical deviation between Hegel and Kant. (shrink)

Niels Bohr’s model of the hydrogen atom is widely cited as an example of an inconsistent scientific theory because of its reliance on classical electrodynamics together with assumptions about interactions between matter and electromagnetic radiation that could not be reconciled with CED. This view of Bohr’s model is controversial, but we believe a recently proposed approach to reasoning with inconsistent commitments offers a promising formal reading of how Bohr’s model worked. In this paper we present this new way of reasoning (...) with inconsistent commitments and compare it with other approaches before applying it to Bohr’s model and offering some suggestions for how it might be extended to account for subsequent developments in old quantum theory. (shrink)

It is a premise of a widely endorsed putative refutation of Anselm's ontological argument that ‘exists’ is not a predicate. This Note argues that although ‘exists’ has the superficial grammatical appearance of a predicate in the Proslogion, Anselm does not in fact rely on the premise that ‘exists’ is a logical predicate in his putative proof. It follows that even if some argument for the conclusion that ‘exists’ is not a predicate is sound, that argument is not a refutation of (...) Anselm's argument. (shrink)

It is a premise of a widely endorsed putative refutation of Anselm's ontological argument that ‘exists’ is not a predicate. This Note argues that although ‘exists’ has the superficial grammatical appearance of a predicate in the Proslogion, Anselm does not in fact rely on the premise that ‘exists’ is a logical predicate (or that existing is a property) in his putative proof. It follows that even if some argument for the conclusion that ‘exists’ is not a predicate is sound, that (...) argument is not a refutation of Anselm's argument. (shrink)

The paper argues for two theses: a) there are certain truths which are analytic; b) these are true by convention. Much of the paper deals with quine's arguments against these claims. The paper starts by accepting quine's network theory of belief and arguing that this presupposes a certain concept of rule following. This may be used to define analyticity. The paper then discusses the conventional nature of rule following and argues that this implies the conventional truth of analytic truths. Quine's (...) arguments against truth by convention are then disarmed. Finally, The paper shows that the account of analyticity given gives rise to a modal logic in the order of s4, Disarming another argument against conventionalism. (shrink)

: Nagarjuna seems willing to embrace contradictions while at the same time making use of classic reductio arguments. He asserts that he rejects all philosophical views including his own-that he asserts nothing-and appears to mean it. It is argued here that he, like many philosophers in the West and, indeed, like many of his Buddhist colleagues, discovers and explores true contradictions arising at the limits of thought. For those who share a dialetheist's comfort with the possibility of true contradictions commanding (...) rational assent, for Nagarjuna to endorse such contradictions would not undermine but instead confirm the impression that he is indeed a highly rational thinker. It is argued that the contradictions he discovers are structurally analogous to many discovered by Western philosophers and mathematicians. (shrink)

In this article, we discuss the notion of merely confused supposition as it arose in the medieval theory of suppositio personalis. The context of our analysis is our formalization of William of Ockham's theory of supposition sketched in Mind 86 (1977), 109-13. The present paper is, however, self-contained, although we assume a basic acquaintance with supposition theory. The detailed aims of the paper are: to look at the tasks that supposition theory took on itself and to use our formalization to (...) relate them to more modern ideas; to explain the notion of merely confused supposition and to defend it against certain criticisms; and to discuss two issues closely related to the idea of merely confused supposition which we could not broach in a shorter article: the mode of supposition of terms in intensional contexts, and the possible existence of a fourth mode, often called suppositio copulatim. (shrink)

The first half of this article is critical: it develops an interpretation of Kant as trying, and failing, to limit our judgments to phenomena and abstain from making claims about noumena, and an interpretation of Wittgenstein as trying, and failing, to develop a theory of meaning that abstains from attempting to say the unsayable. On the reading offered, both Kant and Wittgenstein find themselves saying things that by their own lights cannot be said: in Kant’s case, claims about noumena, and (...) in Wittgenstein’s case, structural claims. While Kant attempts a solution of the problem which also fails, Wittgenstein bites the bullet and leaves his Tractatus, for the most part, void and meaningless. The suggested response is a dialetheic approach—either as an alternative or, potentially, as an amendment to a Kantian or Wittgensteinian theory. According to this approach, certain problems in philosophy arise from true contradictions and thus require a theory that makes sense of contradiction. A subgroup of these problems (among them the noumenal and structural issues in Kant and Wittgenstein) are about things that both are and are not ineffable. The second half of the paper develops a dialetheic account of ineffability and a concise formal theory to ensure that contradiction at the limits of language does not spread to other areas. (shrink)

This paper articulates Sylvan's theory of mathematical objects as non-existent, by improving (arguably) his treatment of the Characterisation Postulate. It then defends the theory against a number of natural objections, including one according to which the account is just platonism in disguise.

Merleau-Ponty's Existential Phenomenology is used to address problems of consciousness, perception, the body, space-time, being, and the limits of science. Arguments are deployed for and against Merleau-Ponty's claims.

When we read On the Origin of Species, we cannot help but hear echoes of the Wealth of Nations. Darwin’s “economy of nature” features a “division of labour” that leads to complexity and productivity. We should not, however, analyze Darwin’s ethics through this lens. Darwin did not draw his economic ideas from Smith, nor did he base his ethics on an economic foundation. Darwin’s ethics rest on Smith’s notion—from the Theory of Moral Sentiments—of an innate human faculty of sympathy. Darwin (...) gave this notion an evolutionary interpretation, concluding that any species of social animals that develops a high enough level of intelligence will evolve moral principles. But the specific moral principles evolved by any particular species will vary, depending on that species’ particular evolutionary history. Darwin’s theory of moral sentiments thus diverged profoundly from Smith’s, while remaining in the same intellectual lineage. Although my reading of Darwin’s ethics departs from the dominant trend, it is not without precedent. A century ago, William James propounded a similar interpretation of Darwin. James’s interpretation has been largely forgotten, but he had Darwin right. It seems that James then developed his own moral philosophy on what he saw as a Darwinian foundation. It may be that James read Darwin’s evolutionary ethics through a pragmatic lens and so refashioned it, in his turn, into something again profoundly different from what Darwin had conceived, but again remaining in the same intellectual lineage. (shrink)

Maurice Merleau-Ponty is known and celebrated as a renowned phenomenologist and is considered a key figure in the existentialist movement. In this wide-ranging and penetrative study, Stephen Priest engages Merleau-Ponty across the full range of his philosophical thought. He considers Merleau-Ponty's writings on the problems of the body, perception, space, time, subjectivity, freedom, language, other minds, physical objects, art and being. Priest addresses Merleau-Ponty's thought in connection with Hegel, Husserl, Heidegger and Sartre. He uses clear and direct language (...) to explain the thoughts of and the ensuing importance of one of the greatest contemporary thinkers. Philosophy students and scholars alike will find great pleasure in this fascinating exploration of the writings and ideas of Maurice Merleau-Ponty. (shrink)

_The Subject in Question_ provides a fascinating insight into a debate between two of the twentieth century's most famous philosophers - Jean-Paul Sartre and Edmund Husserl - over the key notions of conscious experience and the self. Sartre's _The Transcendence of the Ego_, published in 1937, is a major text in the phenomenological tradition and sets the course for much of his later work. _The Subject in Question_ is the first full-length study of this famous work and its influence on (...) twentieth-century philosophy. It also investigates the relationship between Sartre's ideas and the earlier work of Descartes and Kant. (shrink)

One of Da Costa’s motives when he constructed the paraconsistent logic C! was to dualise the negation of intuitionistic logic. In this paper I explore a different way of going about this task. A logic is defined by taking the Kripke semantics for intuitionistic logic, and dualising the truth conditions for negation. Various properties of the logic are established, including its relation to C!. Tableau and natural deduction systems for the logic are produced, as are appropriate algebraic structures. The paper (...) then investigates dualising the intuitionistic conditional in the same way. This establishes various connections between the logic, and a logic called in the literature ‘Brouwerian logic’ or ‘closed-set logic’. (shrink)

This paper concerns two paradoxes involving propositions. The first is Russell's paradox from Appendix B of The Principles of Mathematics, a version of which was later given by Myhill. The second is a paradox in the framework of possible worlds, given by Kaplan. This paper shows a number of things about these paradoxes. First, we will see that, though the Russell/myhill paradox and the Kaplan paradox might appear somewhat different, they are really just variants of the same phenomenon. Though they (...) do this in different ways, the core of each paradox is to use the notion of a proposition to construct a function, f, from the power set of some set into the set itself. Next we will see how this paradox fits into the Inclosure Schema. Finally, I will provide a model of the paradox in question, showing its results to be non‐trivial, though inconsistent. (shrink)

The paper is a discussion of whether Berry's Pardox presupposes the Principle of Excluded Middle, with particular reference to the work of Ross Brady.

David Lewis's untimely death on 14 October 2001 deprived the philosophical community of one of the outstanding philosophers of the 20th century. As many obituaries remarked, Lewis has an undeniable place in the history of analytical philosophy. His work defines much of the current agenda in metaphysics, philosophical logic, and the philosophy of mind and language. This volume, an expanded edition of a special issue of the Australasian Journal of Philosophy, covers many of the topics for which Lewis was well (...) known, including possible worlds, counterpart theory, vagueness, knowledge, probability, essence, fiction, laws, conditionals, desire and belief, and truth. Many of the papers are by very established philosophers; others are by younger scholars including many he taught. The volume also includes Lewis's Jack Smart Lecture at the Australian National University, 'How Many Lives has Schrödinger's Cat?', published here for the first time. Lewisian Themes will be an invaluable resource for anyone studying Lewis's work and a major contribution to the many topics that he mastered. (shrink)