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994What is Mathematical Rigor?Aphex 25 1-17. 2022.Rigorous proof is supposed to guarantee that the premises invoked imply the conclusion reached, and the problem of rigor may be described as that of bringing together the perspectives of formal logic and mathematical practice on how this is to be achieved. This problem has recently raised a lot of discussion among philosophers of mathematics. We survey some possible solutions and argue that failure to understand its terms properly has led to misunderstandings in the literature.
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441Against EthicsEthical Theory and Moral Practice 10 (5): 427-439. 2007.This is the verbatim manuscript of a paper which has circulated underground for close to thirty years, reaching a metethical conclusion close to J. L. Mackie’s by a somewhat different route.
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392A subject with no object: strategies for nominalistic interpretation of mathematicsOxford University Press. 1997.Numbers and other mathematical objects are exceptional in having no locations in space or time or relations of cause and effect. This makes it difficult to account for the possibility of the knowledge of such objects, leading many philosophers to embrace nominalism, the doctrine that there are no such objects, and to embark on ambitious projects for interpreting mathematics so as to preserve the subject while eliminating its objects. This book cuts through a host of technicalities that have obsc…Read more
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292On a derivation of the necessity of identitySynthese 191 (7): 1-19. 2014.The source, status, and significance of the derivation of the necessity of identity at the beginning of Kripke’s lecture “Identity and Necessity” is discussed from a logical, philosophical, and historical point of view
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281Being Explained AwayThe Harvard Review of Philosophy 13 (2): 41-56. 2005.When I first began to take an interest in the debate over nominalism in philosophy of mathematics, some twenty-odd years ago, the issue had already been under discussion for about a half-century. The terms of the debate had been set: W. V. Quine and others had given “abstract,” “nominalism,” “ontology,” and “Platonism” their modern meanings. Nelson Goodman had launched the project of the nominalistic reconstruction of science, or of the mathematics used in science, in which Quine for a time had …Read more
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279Mathematics and bleak housePhilosophia Mathematica 12 (1): 18-36. 2004.The form of nominalism known as 'mathematical fictionalism' is examined and found wanting, mainly on grounds that go back to an early antinominalist work of Rudolf Carnap that has unfortunately not been paid sufficient attention by more recent writers
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225E pluribus unum: Plural logic and set theoryPhilosophia Mathematica 12 (3): 193-221. 2004.A new axiomatization of set theory, to be called Bernays-Boolos set theory, is introduced. Its background logic is the plural logic of Boolos, and its only positive set-theoretic existence axiom is a reflection principle of Bernays. It is a very simple system of axioms sufficient to obtain the usual axioms of ZFC, plus some large cardinals, and to reduce every question of plural logic to a question of set theory
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215Quine, analyticity and philosophy of mathematicsPhilosophical Quarterly 54 (214). 2004.Quine correctly argues that Carnap's distinction between internal and external questions rests on a distinction between analytic and synthetic, which Quine rejects. I argue that Quine needs something like Carnap's distinction to enable him to explain the obviousness of elementary mathematics, while at the same time continuing to maintain as he does that the ultimate ground for holding mathematics to be a body of truths lies in the contribution that mathematics makes to our overall scientific the…Read more
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211Which modal models are the right ones (for logical necessity)?Theoria 18 (2): 145-158. 2003.Recently it has become almost the received wisdom in certain quarters that Kripke models are appropriate only for something like metaphysical modalities, and not for logical modalities. Here the line of thought leading to Kripke models, and reasons why they are no less appropriate for logical than for other modalities, are explained. It is also indicated where the fallacy in the argument leading to the contrary conclusion lies. The lessons learned are then applied to the question of the status o…Read more
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206The sorites paradox and higher-order vaguenessSynthese 85 (3): 417-474. 1990.One thousand stones, suitably arranged, might form a heap. If we remove a single stone from a heap of stones we still have a heap; at no point will the removal of just one stone make sufficient difference to transform a heap into something which is not a heap. But, if this is so, we still have a heap, even when we have removed the last stone composing our original structure. So runs the Sorites paradox. Similar paradoxes can be constructed with any predicate which, like 'heap', displays borderli…Read more
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195Philosophical LogicPrinceton University Press. 2009.Philosophical Logic is a clear and concise critical survey of nonclassical logics of philosophical interest written by one of the world's leading authorities on the subject. After giving an overview of classical logic, John Burgess introduces five central branches of nonclassical logic, focusing on the sometimes problematic relationship between formal apparatus and intuitive motivation. Requiring minimal background and arranged to make the more technical material optional, the book offers a choi…Read more
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175Vague Identity: Evans MisrepresentedAnalysis 49 (3). 1989.In 'Vague Identity: Evans Misunderstood' David Lewis defends Gareth Evans against a widespread misunderstanding of an argument that appeared in his article 'Can There be Vague Objects?'. Lewis takes himself to be 'defending Evans' and not just correcting a mistake; witness his remark that, 'As misunderstood, Evans is a pitiful figure: a "technical philosopher" out of control of his technicalities, taken in by a fallacious proof of an absurd conclusion'. Let me say at the outset that I take Lewis…Read more
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168The truth is never simpleJournal of Symbolic Logic 51 (3): 663-681. 1986.The complexity of the set of truths of arithmetic is determined for various theories of truth deriving from Kripke and from Gupta and Herzberger.
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162Alan Weir. Truth through Proof: A Formalist Foundation for Mathematics. Oxford: Clarendon Press, 2010. ISBN 978-0-19-954149-2. Pp. xiv+281: Critical Studies/Book Reviews (review)Philosophia Mathematica 19 (2): 213-219. 2011.Alan Weir’s new book is, like Darwin’s Origin of Species, ‘one long argument’. The author has devised a new kind of have-it-both-ways philosophy of mathematics, supposed to allow him to say out of one side of his mouth that the integer 1,000,000 exists and even that the cardinal ℵω exists, while saying out of the other side of his mouth that no numbers exist at all, and the whole book is devoted to an exposition and defense of this new view. The view is presented in the book in a way that can ma…Read more
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153What is the simplest and most natural axiomatic replacement for the set-theoretic definition of the minimal fixed point on the Kleene scheme in Kripke’s theory of truth? What is the simplest and most natural set of axioms and rules for truth whose adoption by a subject who had never heard the word "true" before would give that subject an understanding of truth for which the minimal fixed point on the Kleene scheme would be a good model? Several axiomatic systems, old and new, are examined and ev…Read more
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139When is circularity in definitions benign?Philosophical Quarterly 58 (231). 2007.I aim to show how and why some definitions can be benignly circular. According to Lloyd Humberstone, a definition that is analytically circular need not be inferentially circular and so might serve to illuminate the application-conditions for a concept. I begin by tidying up some problems with Humberstone's account. I then show that circular definitions of a kind commonly thought to be benign have inferentially circular truth-conditions and so are malign by Humberstone's test. But his test is to…Read more
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135The unreal futureTheoria 44 (3): 157-179. 1978.Perhaps if the future existed, concretely and individually, as something that could be discerned by a better brain, the past would not be so seductive: its demands would he balanced by those of the future. Persons might then straddle the middle stretch of the seesaw when considering this or that object. It might be fun. But the future has no such reality (as the pictured past and the perceived present possess); the future is but a figure of speech, a specter of thought.
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133Charles Parsons. Mathematical thought and its objectsPhilosophia Mathematica 16 (3): 402-409. 2008.This long-awaited volume is a must-read for anyone with a serious interest in philosophy of mathematics. The book falls into two parts, with the primary focus of the first on ontology and structuralism, and the second on intuition and epistemology, though with many links between them. The style throughout involves unhurried examination from several points of view of each issue addressed, before reaching a guarded conclusion. A wealth of material is set before the reader along the way, but a revi…Read more
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125Which Modal Logic Is the Right One?Notre Dame Journal of Formal Logic 40 (1): 81-93. 1999.The question, "Which modal logic is the right one for logical necessity?," divides into two questions, one about model-theoretic validity, the other about proof-theoretic demonstrability. The arguments of Halldén and others that the right validity argument is S5, and the right demonstrability logic includes S4, are reviewed, and certain common objections are argued to be fallacious. A new argument, based on work of Supecki and Bryll, is presented for the claim that the right demonstrability logi…Read more
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122The Development of Modern LogicHistory and Philosophy of Logic 32 (2). 2011.History and Philosophy of Logic, Volume 32, Issue 2, Page 187-191, May 2011
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118Quinus ab omni naevo vindicatusIn Ali A. Kazmi (ed.), Meaning and Reference, University of Calgary Press. pp. 25--66. 1998.
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117Quinus ab Omni Nævo VindicatusCanadian Journal of Philosophy 27 (sup1): 25-65. 1997.Today there appears to be a widespread impression that W. V. Quine's notorious critique of modal logic, based on certain ideas about reference, has been successfully answered. As one writer put it some years ago: “His objections have been dead for a while, even though they have not yet been completely buried.” What is supposed to have killed off the critique? Some would cite the development of a new ‘possible-worlds’ model theory for modal logics in the 1960s; others, the development of new ‘dir…Read more
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111Mary Leng. Mathematics and Reality. Oxford: Oxford University Press, 2010. ISBN 978-0-19-928079-7. Pp. x + 278: Critical Studies/Book Reviews (review)Philosophia Mathematica 18 (3): 337-344. 2010.(No abstract is available for this citation)
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109TruthPrinceton University Press. 2011.This is a concise, advanced introduction to current philosophical debates about truth. A blend of philosophical and technical material, the book is organized around, but not limited to, the tendency known as deflationism, according to which there is not much to say about the nature of truth. In clear language, Burgess and Burgess cover a wide range of issues, including the nature of truth, the status of truth-value gaps, the relationship between truth and meaning, relativism and pluralism about …Read more
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