Phenomenology, Logic and the Philosophy of Mathematics Richard Tieszen Index More Information
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Arxiv:1204.2193V2 [Math.GM] 13 Jun 2012
Alternative Mathematics without Actual Infinity ∗ Toru Tsujishita 2012.6.12 Abstract An alternative mathematics based on qualitative plurality of finite- ness is developed to make non-standard mathematics independent of infinite set theory. The vague concept \accessibility" is used coherently within finite set theory whose separation axiom is restricted to defi- nite objective conditions. The weak equivalence relations are defined as binary relations with sorites phenomena. Continua are collection with weak equivalence relations called indistinguishability. The points of continua are the proper classes of mutually indistinguishable ele- ments and have identities with sorites paradox. Four continua formed by huge binary words are examined as a new type of continua. Ascoli- Arzela type theorem is given as an example indicating the feasibility of treating function spaces. The real numbers are defined to be points on linear continuum and have indefiniteness. Exponentiation is introduced by the Euler style and basic properties are established. Basic calculus is developed and the differentiability is captured by the behavior on a point. Main tools of Lebesgue measure theory is obtained in a similar way as Loeb measure. Differences from the current mathematics are examined, such as the indefiniteness of natural numbers, qualitative plurality of finiteness, mathematical usage of vague concepts, the continuum as a primary inexhaustible entity and the hitherto disregarded aspect of \internal measurement" in mathematics. arXiv:1204.2193v2 [math.GM] 13 Jun 2012 ∗Thanks to Ritsumeikan University for the sabbathical leave which allowed the author to concentrate on doing research on this theme. 1 2 Contents Abstract 1 Contents 2 0 Introdution 6 0.1 Nonstandard Approach as a Genuine Alternative . -
Arxiv:1809.08676V1 [Math.LO] 23 Sep 2018 Hc Ahmtca O S.I Un U Htti Eednei N Dep Language Is Precise May Dependence Game
NAMING THE LARGEST NUMBER EXPLORING THE BOUNDARY BETWEEN MATHEMATICS AND THE PHILOSOPHY OF MATHEMATICS DAVID SIMMONS Abstract. What is the largest number accessible to the human imagination? The ques- tion is neither entirely mathematical nor entirely philosophical. Mathematical formula- tions of the problem fall into two classes: those that fail to fully capture the spirit of the problem, and those that turn it back into a philosophical problem. 1. Introduction “You have fifteen seconds. Using standard math notation, English words, or both, name a single whole number–not an infinity–on a blank index card. Be precise enough for any reasonable modern mathematician to determine exactly what number you’ve named, by consulting only your card and, if necessary, the published literature. Are you ready? Get set. Go.” – Scott Aaronson, “Who can Name the Bigger Number?” 1 “The game of describing the largest integer, when played by experts, lapses into a hopeless argument over legitimacy.” – Joel Spencer, “Large numbers and unprovable theorems” [8] This paper addresses the question: what is the best strategy in a “name the largest number” contest such as the one described above? Of course, the answer depends on arXiv:1809.08676v1 [math.LO] 23 Sep 2018 what the rules of the contest are. Scott Aaronson’s idea of letting a “reasonable modern mathematician” judge the entries might sound fair at first, but the answer to the question of whether a given entry is a precise description of a number may depend on exactly which mathematician you ask. It turns out that this dependence is not incidental but fundamental, and slightly different standards for what counts as a valid entry give rise to radically different strategies for winning the game. -
Model Theory of Ultrafinitism I: Fuzzy Initial Segments of Arithmetic
Model Theory of Ultrafinitism I: Fuzzy Initial Segments of Arithmetic (Preliminary Draft) Mirco A. Mannucci Rose M. Cherubin February 1, 2008 Abstract This article is the first of an intended series of works on the model the- ory of Ultrafinitism. It is roughly divided into two parts. The first one addresses some of the issues related to ultrafinitistic programs, as well as some of the core ideas proposed thus far. The second part of the paper presents a model of ultrafinitistic arithmetics based on the notion of fuzzy initial segments of the standard natural numbers series. We also introduce a proof theory and a semantics for ultrafinitism through which feasibly consistent theories can be treated on the same footing as their classically consistent counterparts. We conclude with a brief sketch of a foundational program, that aims at reproducing the transfinite within the finite realm. 1 Preamble To the memory of our unforgettable friend Stanley ”Stan” Tennen- baum (1927 − 2005), Mathematician, Educator, Free Spirit As we have mentioned in the abstract, this article is the first one of a series dedicated to ultrafinitistic themes. arXiv:cs/0611100v1 [cs.LO] 21 Nov 2006 First papers often tend to take on the dress of manifestos, road maps, or both, and this one is no exception. It is the revised version of an invited conference talk, and was meant from the start for a quite large audience of philosophers, logicians, computer scientists, and mathematicians, who might have some in- terest in the ultrafinite. Therefore, neither the philosophico-historical, nor the mathematical side, are meant to be detailed investigations. -
A Finitist's Manifesto: Do We Need to Reformulate the Foundations Of
A Finitist’s Manifesto: Do we need to Reformulate the Foundations of Mathematics? Jonathan Lenchner 1 The Problem There is a problem with the foundations of classical mathematics, and potentially even with the foundations of computer science, that mathematicians have by-and-large ignored. This essay is a call for practicing mathematicians who have been sleep-walking in their infinitary mathematical paradise to take heed. Much of mathematics relies upon either (i) the “existence” of objects that contain an infinite number of elements, (ii) our ability, “in theory”, to compute with an arbitrary level of precision, or (iii) our ability, “in theory”, to compute for an arbitrarily large number of time steps. All of calculus relies on the notion of a limit. The monumental results of real and complex analysis rely on a seamless notion of the “continuum” of real numbers, which extends in the plane to the complex numbers and gives us, among other things, “rigorous” definitions of continuity, the derivative, various different integrals, as well as the fundamental theorems of calculus and of algebra – the former of which says that the derivative and integral can be viewed as inverse operations, and the latter of which says that every polynomial over C has a complex root. This essay is an inquiry into whether there is any way to assign meaning to the notions of “existence” and “in theory” in (i) to (iii) above. On the one hand, we know from quantum mechanics that making arbitrarily precise measure- ments of objects is impossible. By the Heisenberg Uncertainty Principle the moment we pin down an object, typically an elementary particle, in space, thereby bringing its velocity, and hence mo- mentum, down to near 0, there is a limit to how precisely we can measure its spatial coordinates. -
True History of Strict Finitism
A True(r) History of Strict Finitism Jean Paul Van Bendegem Vrije Universiteit Brussel Center for Logic and Philosophy of Science Universiteit Gent Confusion about what strict finitism is ° Both historical roots ° As what its meaning is Different names: ° Strict finitism ° Ultrafinitism ° Ultra-intuitionism Aim: to clarify matters (a bit) The “founding father” (usually mentioned as such) Alexander Yessenin-Volpin (sometimes Essenine-Volpin of Ésenine-Volpine) • ultra-intuitionism • articles quite cryptic • no direct interest in finitism • different aim (finitary consistency proof) YESSENIN-VOLPIN, A. S. : "Le programme ultra- intuitioniste des fondements des mathématiques". In: Infinitistic Methods, Proceedings Symposium on Foundations of Mathematics, Pergamon Press, Oxford, 1961, pp. 201-223. YESSENIN-VOLPIN, A. S. : "The ultra-intuitionistic criticism and the antitraditional program for foundations of mathematics". In: KINO, MYHILL & VESLEY (eds.), Intuitionism & proof theory. North-Holland, Amsterdam, 1970, pp. 3-45. YESSENIN-VOLPIN, A. S. : "About infinity, finiteness and finitization". In RICHMAN, F. (ed.), 1981, pp. 274-313. “Zenonian” sets Z: • if n belongs to Z, so does n+1 • Z is nevertheless finite in its entirety example : the collection of heartbeats in your youth But see: James R. Geiser: “A Formalization of Essenin-Volpin's Proof Theoretical Studies by Means of Nonstandard Analysis” (JSL, Vol. 39, No. 1, 1974, pp. 81-87) for an attempt at rigorous reconstruction “Take, for example, the unusual answer proposed by Alexander Yessenin-Volpin (Aleksandr Esenin-Volpin), a Russian logician of the ultra-finitist school who was imprisoned in a mental institution in Soviet Russia. Yessenin-Volpin was once asked how far one can take the geometric series of powers of 2, say (2 1, 2 2, 2 3, …, 2100 ). -
Abstract This Book Explores Arguments for and Against Moral
Abstract This book explores arguments for and against moral realism and mathematical realism, how they interact, and what they can tell us about areas of philosophical interest more generally. It argues that our mathematical beliefs have no better claim to being self-evident or provable than our moral beliefs. Nor do our mathematical beliefs have better claim to being empirically justified. It is also incorrect that reflection on the “genealogy” of our moral beliefs establishes a lack of parity between the cases. In general, if one is a moral anti-realist on the basis of epistemological considerations, then one ought to be a mathematical anti-realist too. And yet, the book argues that moral realism and mathematical realism do not stand or fall together – and for a surprising reason. Moral questions, insofar as they are practical, are objective in a sense in which mathematical questions are not, and the sense in which they are objective can only be explained by assuming practical anti-realism. It follows that the concepts of realism and objectivity, which have been widely identified, are actually in tension. The author concludes that the objective questions in the neighborhood of questions of logic, modality, grounding, nature, and more are practical questions as well. Practical philosophy should, therefore, take center stage. Keywords morality, mathematics, realism, anti-realism, objectivity, practical, self-evidence, proof, genealogy, Benacerraf, logic, Indispensability Argument, Open Question Argument, <p. i: half-title page, recto> Morality and Mathematics <p. ii: half-title page, verso: blank> <p. iii: title page, recto> Morality and Mathematics JUSTIN CLARKE-DOANE OXFORD UNIVERSITY PRESS <p. -
Potential Versus Actual Infinity: Insights from Reverse Mathematics
Potential versus actual infinity: insights from reverse mathematics Stephen G. Simpson Pennsylvania State University http://www.math.psu.edu/simpson/ [email protected] Annual Logic Lecture Group in Philosophical and Mathematical Logic University of Connecticut April 1–3, 2015 1 Potential infinity versus actual infinity. An important philosophical distinction: Definition. A potential infinity is a quantity which is finite but indefinitely large. For instance, when we enumerate the natural numbers as 0, 1, 2,...,n,n + 1,..., the enumeration is finite at any point in time, but it grows indefinitely and without bound. Another example is the enumeration of all finite sequences of 0’s and 1’s. Definition. An actual infinity is a completed infinite totality. Examples: N, R, C[0, 1], L2[0, 1], etc. Other examples: gods, devils, etc. Reference: Aristotle, Metaphysics, Books M and N. 2 Four philosophical positions. Ultrafinitism: Infinities, both potential and actual, do not exist and are not acceptable in mathematics. Finitism: Potential infinities exist and are acceptable in mathematics. Actual infinities do not exist and we must limit or eliminate their role in mathematics. Predicativism: We may accept the natural numbers, but not the real numbers, as a completed infinite totality. Quantification over N is acceptable, but quantification over R, or over the set of all subsets of N, is unacceptable. Infinitism: Actual infinities of all kinds are welcome in mathematics, so long as they are consistent and intuitively natural. Of these four positions, the finitist one seems to be the most objective. 3 Definition. By the real world we mean the real world around us and out there, as grasped by our minds. -
Philosophy of Mathematics
PHILOSOPHY OF MATHEMATICS Justin Clarke-Doane Meeting Details Friday 4:10pm-6pm in 716 Philosophy Hall 712B Philosophy Hall Phone: 212-854-3246 Requirements Office Hours: By Appointment Participation counts for 20% of your grade. [email protected] A paper of ≈ 20 pages counts for 80%. Summary Mathematics is often regarded as the most successful discipline. But like most -- maybe all -- disciplines, the picture is complicated on inspection. Disagreements persist over axioms and standards of proof. Independence results threaten the objectivity and determinacy of the subject. And the question of how human beings could acquire anything approximating the knowledge of mathematics we take ourselves to have acquired remains wide open. All of this might be thought to recommend some kind of “anti-realism” about mathematics. But, to add insult to injury, our best -- and only! -- comprehensive theories of the mind-independent world are up to their ears in abstract mathematics. In this seminar, we will try to figure out what to make of this situation. Useful References Computability and Logic (Boolos, Jeffrey, and Burgess) Set Theory: An Introduction to Independence Proofs (Kunen) Logical Foundations of Mathematics and Computational Complexity Theory (Pudlak) A Tour Through Mathematical Logic (Wolf) Note: All readings will be available electronically. Selections TBD. Week 1: Logicism, Intuitionism, and Formalism Carnap, “The Logicist Foundation of Mathematics” (in Benacerraf and Putnam) Heyting, “The Intuitionist Foundation of -
Draft. Please Do Not Quote) 2 Preface
1 Not Exactly in Praise of Vagueness by Kees van Deemter University of Aberdeen (Draft. Please do not quote) 2 Preface Vagueness is the topic of quite a few scholarly books for professional academics. This book targets a much broader audience. For this reason, the exposition has been kept as informal as possible, focussing on the essence of an idea rather than its technical incarnation in formulas or computer programs. Most chapters of the book (with the exception of chapters 8 and 9, which rely on the material explained in earlier chapters) are self-explanatory. In a few areas of substantial controversy, I have used fictional dialogues – a tried and tested method since Plato’s days of course – to give readers a sense of the issues. Although some things have been too complex to yield willingly to this treatment, it has been a delight to discover how much complex material can be reduced to simple ideas. On a good day, it even seems to me that there are themes that are best explored in this informal way, free from the constraints of an academic straightjacket. The fact that the book is informal may not always make it an easy read. For one thing, it requires a somewhat philosophical spirit, in which one asks why certain well-known facts hold. Moreover, we will not be content when we, sort of, dimly understand why something happens: we will ask how this understanding can be given a place in a known theory. Essentially this means that we will insist on trying to understand vagueness in a way that is compatible with everything else we know about the world. -
Philosophical Problems in Logic Lecture 1 9/25/02
1 Philosophy 532 and Philosophy 536 were the two seminars I presented while on leave at the Princeton University Philosophy Department, Fall, 2002. Harvey M. Friedman PHILOSOPHY 532 PHILOSOPHICAL PROBLEMS IN LOGIC LECTURE 1 9/25/02 "Mathematics is the only major subject which has been given a philosophically credible foundation." This is widely accepted, inside and outside philosophy, but one can spend an entire career clarifying, justifying, and amplifying on this statement. Certainly a graduate student career. This could entail clarifying what is meant by "mathematics". Or "major subject". Or for that matter, "subject". Also "given". And of course "philosophically credible foundation", or even just "foundation". We are almost down to the level of something manageable. In what sense do we have a "foundation" for mathematics? A "foundation" in the sense that we don't have for other subjects such as physics, statistics, biology, law, history, literary/music criticism or philosophy? Before I get to the principal features of foundations of mathematics, let us first touch on "what is mathematics?" Of course, we do not expect any kind of remotely definitive answer to such a question. But it is common to focus on just one aspect of this question. How does mathematics compare to the (other?) sciences in terms of its relationship to "reality"? Let me focus this a bit. Nobody(?) would compare physics with, say, the study of "the causes of the U.S. Civil War". In one case, we are endeavoring to uncover "fundamental" facts about "external reality", which can be "tested" by repeated "objective" experiments. In the other case, we are doing something radically(?) different. -
Unified Approach to Real Numbers in Various Mathematical Settings
Unified Approach to Real Numbers in Various Mathematical Settings Davorin Leˇsnik Department of Mathematics Darmstadt University of Technology, Germany [email protected] February 27, 2014 Abstract We provide a setting-independent definition of reals by introducing the notion of a streak. We show that various standard constructions of reals satisfy our definition. We study the structure of reals by noting that its pieces correspond to reflections on the category of streaks. 1 Introduction Real numbers form one of the most important sets in mathematics. There are different definitions of reals, the most common one probably being: R is a Dedekind complete ordered field. It turns out that in classical mathematics this definition determines R up to isomorphism (so we have uniqueness), and one can construct models, satisfying this definition (thus proving existence), such as Cauchy reals (equivalence classes of Cauchy sequences of rationals), Dedekind arXiv:1402.6645v1 [math.GM] 24 Feb 2014 reals (Dedekind cuts) etc. If there is little doubt, what reals are classically, the answer is not so clear-cut in various constructive settings. Constructively the definition “Dedekind com- plete ordered field” doesn’t work (for example, it does not imply the archimedean property) and different constructions of reals don’t necessarily yield isomorphic sets (for example, depending on the constructive setting, there can be more Dedekind reals than Cauchy ones). It is not apparent that one construction would be inherently better than the other, and one usually uses the one which behaves best in the current setting. This paper is an attempt to make a unifying definition for reals in a wide variety of settings, by making only some very basic assumptions on the background theory. -
What Do You Claim When You Say You Have a Proof?
What do you claim when you say you have a proof? Claus Diem and Christoph Schulze May 19, 2019 Prologue In the common room disciple: Your proof was quite beautiful. speaker: Thank you! disciple: Actually, sometimes, I had a bit a problem following. There was quite a jump from the Fundamental Lemma to Theorem A. speaker: Well, yes, because the time was short. But I can give the details. disciple: Rigorous? speaker: Yes, of course. disciple: And Theorem B? speaker: The Fundamental Lemma also implies Theorem B; you can adapt the proof for Theorem A. disciple: So, you have proven the theorems? speaker: Yes, I have a proof otherwise I wouldn't say I have theo- rems. disciple: Of course. skeptic: I've overheard your conversation. I would like to know what you mathematicians mean when you say that you have a proof. That does not seem so obvious to me. disciple: That we can demonstrate it rigorously. skeptic: This means in the basis of ZFC? speaker: Yes, you can say that by default option this means on the basis of ZFC. skeptic: So you say that you have proof of your theorems on the basis of ZFC? speaker: Yes ... 1 skeptic: There was nothing remotely similar to proofs on the basis of ZFC on the blackboard. speaker: I outlined it. It requires work but you can convince yourself: One can give formal proofs on the basis of ZFC. skeptic: I couldn't, that's for sure. But I am sure that you couldn't do it either. speaker: Well, literally speaking maybe, at least I wouldn't do it.