Philosophy of Mathematics

Centered around our knowledge of mathematical, modal, and a priori truths, this is a collection that celebrates the work of Keith Hossack, who, throughout his career, has made outstanding contributions to the theory of knowledge, metaphysics, and the philosophy of mathematics. Starting with a focus on our knowledge of abstract entities such as mathematical objects and the source of the necessity of mathematical truths, attention moves to the notion of necessity and its interaction with a priori knowledge: Is it the (...) case that a proposition is necessarily true precisely when it is known a priori? Coverage concludes by zooming out to offer new perspectives on the theory of knowledge: What is knowledge? Is knowing a relation between an agent and a fact? How can we explain rational ignorance by a theory of content? How can we know the content of our own minds, and what does it tell us about the role of a priori knowledge? Featuring chapters by colleagues and students of Hossack's, a team of contributors that includes established philosophers and up and coming academics, Knowledge, Number and Reality represents some of the most vibrant discussions taking place in analytic philosophy today. (shrink)

Kripke observes that the decimal numerals have the buck-stopping property: when a number is given in decimal notation, there is no further question of what number it is. What makes them special in this way? According to Kripke, it is because of structural revelation: each decimal numeral represents the structure of the corresponding number. Though insightful, I argue, this account has some counterintuitive consequences. Then I sketch an alternative account of the buck-stopping property in terms of how we specify the (...) positions of numbers in the progression. (shrink)

ABSTRACT How do non-experts single out numbers for reference? Linnebo has argued that they do so using a criterion of identity based on the ordinal properties of numerals. Neo-logicists, on the other hand, claim that cardinal properties are the basis of individuation, when they invoke Hume’s Principle. I discuss empirical data from cognitive science and linguistics to answer how non-experts individuate numbers better in practice. I use those findings to develop an alternative account that mixes ordinal and cardinal properties to (...) provide a detailed answer to the question: how do we in fact semantically individuate numbers? (shrink)

This book seeks to offer original answers to all the major open questions in epistemology—as indicated by the book’s title. These questions and answers arise organically in the course of a validation of the entire corpus of human knowledge. The book explains how we know what we know, and how well we know it. The author presents a positive theory, motivated and directed at every step not by a need to reply to skeptics or subjectivists, but by the need of (...) a rational individual to know the world. -/- The author draws heavily from Ayn Rand’s theory of concepts as presented in her book, Introduction to Objectivist Epistemology, but departs from her epistemology—especially as explicated by leading exponents of her philosophy—in important ways. Areas of departure include the perception of entities and the role of probability theory in epistemology. -/- A main idea in the book is to begin the validation of the law of causality by identifying that existence causes our consciousness of it. Another key idea is this: The very fact that we perceive entities is the most basic and most extensive evidence that causal forces and causal interactions are regular. -/- Applying Ayn Rand’s principle that characteristics are ranges of measurement, the book offers a philosophical validation of “nonparametric predictive inference,” in turn providing an objective basis for prior probabilities in Bayesian analysis. -/- This book is primarily for a specialized readership—familiar with epistemological ideas and with Ayn Rand’s theory of concepts in particular. The last third of the book uses probability theory and mathematics somewhat beyond basic calculus, but less mathematical explanations are also included to make the general ideas accessible to lay readers. (shrink)

ABSTRACT The aim of the paper is to answer some arguments raised against mathematical structuralism developed by Michael Resnik. These arguments stress the abstractness of mathematical objects, especially their causal inertness, and conclude that mathematical objects, the structures posited by Resnik included, are inaccessible to human cognition. In the paper I introduce a distinction between abstract and ideal objects and argue that mathematical objects are primarily ideal. I reconstruct some aspects of the instrumental practice of mathematics, such as symbolic manipulations (...) or ruler-and-compass constructions, and argue that instrumental practice can secure epistemic access to ideal objects of mathematics. (shrink)

This book intends to show that, in philosophy of mathematics, radical naturalism (or physicalism), nominalism and strict finitism (which does not assume the reality of infinity in any format, not even potential infinity) can account for the applications of classical mathematics in current scientific theories about the finite physical world above the Planck scale. For that purpose, the book develops some significant applied mathematics in strict finitism, which is essentially quantifier-free elementary recursive arithmetic (with real numbers encoded as elementary recursive (...) Cauchy sequences of rational numbers). Applied mathematical theories developed in the book include the basics of calculus, metric space theory, complex analysis, Lebesgue integration, Hilbert spaces, and semi-Riemann geometry (sufficient for the basic applications in classical quantum mechanics and general relativity). The fact that so much applied mathematics can be developed within such a weak, strictly finitisitc system is perhaps surprising in itself. It also shows that the applications of those classical theories to the finite physical world can be translated into the applications of strict finitism, which demonstrates the applicability of those classical theories without assuming the literal truth of those theories or the reality of infinity. The first chapter of the book contains an informal introduction to its philosophical motivation and technical strategy. The book is intended for students and researchers in philosophy of mathematics. -/- Contents -/- Preface 1 Introduction 2 Strict Finitism 3 Calculus 4 Metric Space 5 Complex Analysis 6 Integration 7 Hilbert Space 8 Semi-Riemann Geometry References Index. (shrink)

This book develops and defends a version of physicalism in contemporary philosophy of mind, called ‘No-Self Physicalism’. No-Self Physicalism emphasizes that a subject of cognition is itself a physical entity, a human brain (and body). -/- The book first argues (in Chapters 1 and 2) that many contemporary philosophers who openly accept physicalism in fact (though perhaps unconsciously and/or implicitly) take the stance of a non-physical Subject in understanding and using core philosophical notions, such as conceptual representation, truth, analyticity, modality, (...) apriority, abstract object, knowledge and intuition. That is, they appear to be unaware that our traditional understandings of these philosophical notions presuppose a non-physical Subject. They appear to be unaware that these notions need a radical overhaul to become meaningful if, according to physicalism, the subject of cognition is itself a plain physical object, not any obscure, amorphous, non-physical, soul-like Subject. This problem threatens the coherence of many contemporary philosophers’ philosophical positions. -/- Then, the bulk of this book (Chapters 3 to 7) consists of laborious efforts to develop truly physicalistic theories on some core philosophical notions and issues, including (in the order of presentation in this book) concepts and conceptual representation, thoughts and truth, belief ascription, analyticity, modality, the nature of mathematics, epistemic justification, knowledge, apriority, intuition, and a physicalistic ontology. These physicalistic theories explicitly assume that a subject of cognition is a human brain (and body), or a neural network-based robot programmed by evolution. They are new and are more clearly physicalistic if compared with their alternatives in the current literature. Finally, the last chapter (Chapter 8) of this book uses the physicalistic notions of conceptual representation, truth, analyticity, modality, knowledge, apriority, intuition, and the physicalistic ontology developed in previous chapters to formulate physicalism as a general philosophical worldview. This is then an internally coherent formulation of physicalism, using only naturalized philosophical notions. It helps to settle the current debates between different versions of physicalism. -/- Therefore, on the one side, this book tries to push physicalism to its extreme, in its most radical format, by emphasizing that the cognitive subject is itself a completely physical thing, a neural network-based robot programmed by evolution, but on the other side, by some hard work, some honest toil, it tries to demonstrate that this minimal physicalistic framework can already offer accounts for many core philosophical notions and issues that traditionally interest philosophers, namely, conceptual representation, truth, analyticity, belief ascription, modality, the nature of mathematics, epistemic justification, knowledge, apriority, intuition and some ontological issues. It is meant to be a self-contained presentation of a very radical and strict version of physicalism while at the same time showing how surprisingly comprehensive this version could be. (shrink)

The contributions to this volume are from participants of the international conference "Kreisel's Interests - On the Foundations of Logic and Mathematics", which took place from 13 to 14 2018 at the University of Salzburg in Salzburg, Austria. The contributions have been revised and partially extended. Among the contributors are Akihiro Kanamori, Göran Sundholm, Ulrich Kohlenbach, Charles Parsons, Daniel Isaacson, and Kenneth Derus. The contributions cover the discussions between Kreisel and Wittgenstein on philosophy of mathematics, Kreisel's Dictum, proof theory, the (...) discussions between Kreisel and Gödel on philosophy of mathematics, some bibliographical facts, and a collection of extracts from Kreisel's letters. (shrink)

In this article Russell’s paradox and Cantor’s paradox resolved successfully using intuitionistic logic with restricted modus ponens rule.

This article has been written about the explanation of the scientific affair. There are the philosophical circles that a philosopher must consider their approaches. Postmodern thinkers generally refuse the universality of the rational affair. They believe that the experience cannot reach general knowledge. They emphasize on the partial and plural knowledge. Any human being has his knowledge and interpretation. The world is always becoming. Diversity is an inclusive epistemological principle. Naturally, in such a state, the scientific activity is a non-sense (...) process. The postmodern world is a post-scientific world. Another collection of approaches to science belongs to the analytical philosophy. The main part of analytical philosophy context centers around language. Language is the center of the world. We can study the world through language. Language is the possibility of knowledge. If we overcome the language games, we can study the world accurately. Generally, at present, it seems that the rational thoughts are marginal points in the sea of irrationality. We can probably talk about an anarchistic epistemological situation. Another issue is the role of observation to form a scientific activity. In this situation, the question is whether the observation is the technique of gathering information or the final reference of original scientific analysis. In relation to this issue, the confrontation of science with the families and the categories of the objects is the main problem. For more than two thousand years, the totalitarian heritage of the Aristotelian logic has been the guideline of categorizations for the human being. In order to reach an inclusive and applicable result, we should categorize everything; but it is not really known that if the method of the world categorization is the same or not. The accordance of the conceptual categories with their extensions in the world is one of the main problems which has malfunctioned the scientific system. It is better to say that it has deactivated science. Moreover, there are many interpretations for each event based on its occurrence conditions. For example, consider a fever; In order to diagnose its cause, the most significant factor is the role of a physician. There is no sense in saying that the observation has diagnosed the cause of the fever. This is the observer that plays a determinative role. Another problem is the disputes between realism and instrumentalism. Instrumentalists believe that to form a theory, the concepts are just the tools of scientific researches. Based on realism, but we confront the concepts in the original way. This chaos causes the scientific system to collapse. Now the question is what the solution is. I would like to propose my scheme that is constructed based on a main principle: there is no occurrence in the world unless we can trace the effect of consciousness back in that occurrence. In other words, there is no accident in the world. One can argue that it is the main problem that the effects of consciousness ---if there is such a concept--- is not traceable in the world. An immediate response to this problem is an inefficient technique . The observation is a technique . It is not the method of interpretation. Some people argue that the empirical approach cannot lead us to an authentic criterion to know the world. Because there is no criterion for truth, and if there is probably such a criterion, we can obtain it via several ways. The solution to the first problem is simple. Any occurrence is a truth; even we suppose it as a partial truth. Therefore we can say we face a multi-facial world. It can be the solution of the second problem: if consciousness is essentially the origin of the world and all occurrences, we face consciousness as a unique truth; even its creations contradict each other. If there is no consciousness as a creator of the world and we cannot trace it back in all existents, then what should we do? If there is consciousness, why its creations contradict each other. Since consciousness is a will, it is able to decide in any situation it intends. The issue of contradictory consciousness intentions has a teleological aspect. We cannot judge its teleological substance at present. If we are able to believe that there is no consciousness at all, it will contradict the main practical principle in our lives. Every action that we take in our lives is conjoined with consciousness. We learn many things from many sources. The substance of our instincts and emotions can be questioned. It is true that we cannot actually analyze our instincts and emotions, but we can discuss explicitly about the rational elements of the instincts. What are these elements? These elements are the quality of their appearance. The quality of instinct appearance is different among beings. The strength and the depth and length of these irrational qualities are different in all beings. What factors or factor cause the differences among these aspects? There is certainly a determinative factor. The same factor which determines the occurrence of any event. Even if we believe in partial knowledge, we must accept the confrontation of the occurrences. Thus it is not possible to refuse the occurrences as the reference unit of knowledge. In spite of the difference, every occurrence, even as a single occurrence, happens and we can regard it as the reference unit of knowledge. Then we can consider every occurrence as an occurred object. When an occurrence happens, then it is a determined object. Everywhere there is a determination, there is certainly a determiner. Why do not we encounter a multi-determinative consciousness? Because there are a few aspects of the unique super-consciousness. These aspects are motion and growth and the amount of constituent material in every being. In all over the world, the difference in these factors creates all differences. Thus we do not encounter the plural consciousness. Is the world birth accidental? Actually, there is no accident. The accident has no meaning in the world. As explained above, the constructing element of the world is the occurrence. An occurrence can be analyzed. Therefore, we should not talk about the accident until we are not able to analyze all phenomena. We can look at every subject from different points of view at present. Thus there is theoretically no possibility to say that a certain matter is the consequence of the accident. The accident is a popular and inexact concept that has no philosophical content. Moreover, the definition of consciousness versus its contradiction causes the collapse of all epistemological axioms. We can ask why we must not define other logical principles against their contradictions. Thinkers who deny the role of logic usually ignore the role of logic. They have not been able to deny the logical function to form an epistemological system because it is not an easy task. In this article some other issues were discussed, such as the consideration of restriction as a stable and firm foundation of knowledge instead of the Descartes cogito. In addition to these philosophical points some other issues were propounded such as the role of instrumental mechanism to form the new science and the great alterations in philosophy and history of Europe. Many issues threaten human civilization. The only way to deal with such threats is certainly to use scientific facilities. The scientific possibilities undoubtedly come from a complete and inclusive scientific theory. The present article is an attempt to explain the scientific affair in order to develop human achievement, however small. (shrink)

What the Josephson Junction proves. The Josephson-Yardley 'connection.'.

Norbert Wiener’s idea of “cybernetics” is linked to temporality as in a physical as in a philosophical sense. “Time orders” can be the slogan of that natural cybernetics of time: time orders by itself in its “screen” in virtue of being a well-ordering valid until the present moment and dividing any totality into two parts: the well-ordered of the past and the yet unordered of the future therefore sharing the common boundary of the present between them when the ordering is (...) taking place by choices. Thus, the quantity of information defined by units of choices, whether bits or qubits, describes that process of ordering happening in the present moment. The totality (which can be considered also as a particular or “regional” totality) turns out to be divided into two parts: the internality of the past and the externality of the future by the course of time, but identifiable to each other in virtue of scientific transcendentalism (e.g. mathematical, physical, and historical transcendentalism). A properly mathematical approach to the “totality and time” is introduced by the abstract concept of “evolutionary tree” (i.e. regardless of the specific nature of that to which refers: such as biological evolution, Feynman trajectories, social and historical development, etc.), Then, the other half of the future can be represented as a deformed mirror image of the evolutionary tree taken place already in the past: therefore the past and future part are seen to be unifiable as a mirrorly doubled evolutionary tree and thus representable as generalized Feynman trajectories. The formalism of the separable complex Hilbert space (respectively, the qubit Hilbert space) applied and further elaborated in quantum mechanics in order to uniform temporal and reversible, discrete and continuous processes is relevant. Then, the past and future parts of evolutionary tree would constitute a wave function (or even only a single qubit once the concept of actual infinity be involved to real processes). Each of both parts of it, i.e. either the future evolutionary tree or its deformed mirror image, would represented a “half of the whole”. The two halves can be considered as the two disjunctive states of any bit as two fundamentally inseparable (in virtue of quantum correlation) “halves” of any qubit. A few important corollaries exemplify that natural cybernetics of time. (shrink)

ABSTRACT In this paper, I evaluate the claim that the equivalence of multiple intensionally distinct definitions of random sequence provides evidence for the claim that these definitions capture the intuitive conception of randomness, concluding that the former claim is false. I then develop an alternative account of the significance of randomness-theoretic equivalence results, arguing that they are instances of a phenomenon I refer to as schematic equivalence. On my account, this alternative approach has the virtue of providing the plurality of (...) definitions of randomness with conceptual unity and a rationale for certain investigations that are carried out in the field. (shrink)

We argue that, under the usual assumptions for sufficiently strong arithmetical theories that are subject to Gödel’s First Incompleteness Theorem, one cannot, without impropriety, talk about *the* Gödel sentence of the theory. The reason is that, without violating the requirements of Gödel’s theorem, there could be a true sentence and a false one each of which is provably equivalent to its own unprovability in the theory if the theory is unsound.

Summary This article presents three hitherto unpublished letters by Frank Plumpton Ramsey on the foundations of mathematics with commentary. One of the letters was sent to Abraham Fraenkel and the other two letters to Heinrich Behmann. The transcription of the letters is preceded by an account that details the extent of Ramsey's known contacts with mathematical logicians on the Continent.

It is an established part of mathematical practice that mathematicians demand -/- deductive proof before accepting a new result as a theorem. However, a wide -/- variety of probabilistic methods of justification are also available. Though such -/- procedures may endorse a false conclusion even if carried out perfectly, their -/- robust structure may mean they are actually more reliable in practice once implementation -/- errors are taken into account. Can mathematicians be rational -/- in continuing to reject these probabilistic (...) methods as a means of establishing a -/- mathematical claim? In this paper, I give reasons in favour of their doing so. -/- Rather than appealing directly to individual epistemological considerations, the -/- discussion offers a normative constraint on what constitutes a good mathematical -/- argument. This I call ‘Univocality’, the requirement that the underlying -/- concepts all have clear defining conditions. (shrink)

A computational methodology called Grossone Infinity Computing introduced with the intention to allow one to work with infinities and infinitesimals numerically has been applied recently to a number of problems in numerical mathematics (optimization, numerical differentiation, numerical algorithms for solving ODEs, etc.). The possibility to use a specially developed computational device called the Infinity Computer (patented in USA and EU) for working with infinite and infinitesimal numbers numerically gives an additional advantage to this approach in comparison with traditional methodologies studying (...) infinities and infinitesimals only symbolically. The grossone methodology uses the Euclid’s Common Notion no. 5 ‘The whole is greater than the part’ and applies it to finite, infinite, and infinitesimal quantities and to finite and infinite sets and processes. It does not contradict Cantor’s and non-standard analysis views on infinity and can be considered as an applied development of their ideas. In this paper we consider infinite series and a particular attention is dedicated to divergent series with alternate signs. The Riemann series theorem states that conditionally convergent series can be rearranged in such a way that they either diverge or converge to an arbitrary real number. It is shown here that Riemann’s result is a consequence of the fact that symbol ∞ used traditionally does not allow us to express quantitatively the number of addends in the series, in other words, it just shows that the number of summands is infinite and does not allows us to count them. The usage of the grossone methodology allows us to see that (as it happens in the case where the number of addends is finite) rearrangements do not change the result for any sum with a fixed infinite number of summands. There are considered some traditional summation techniques such as Ramanujan summation producing results where to divergent series containing infinitely many positive integers negative results are assigned. It is shown that the careful counting of the number of addends in infinite series allows us to avoid this kind of results if grossone-based numerals are used. (shrink)

ABSTRACT This paper examines consequences of the computer revolution in mathematics. By comparing its repercussions with those of conceptual developments that unfolded in the nineteenth century, I argue that the key epistemological lesson to draw from the two transformative periods is that effective and successful mathematical practices in science result from integrating the computational and conceptual styles of mathematics, and not that one of the two styles of mathematical reasoning is superior. Finally, I show that the methodology deployed by applied (...) mathematicians in modern scientific computing is a paradigmatic instance of this key lesson. (shrink)

In his recent book, Quine, New Foundations, and the Philosophy of Set Theory, Sean Morris attempts to rehabilitate Quine’s NF as a possible foundation for mathematics. I explain why he does not succeed.

It is well known that Felix Klein took a decisive step in investigating the invariants of transformation groups. However, less attention has been given to Klein’s considerations on the epistemological implications of his work on geometry. This paper proposes an interpretation of Klein’s view as a form of mathematical structuralism, according to which the study of mathematical structures provides the basis for a better understanding of how mathematical research and practice develop.

_Erich Reck* * and Georg Schiemer.** ** The Prehistory of Mathematical Structuralism. _Oxford University Press, 2020. Pp. 454. ISBN: 978-0-19-064122-1 ; 978-0-19-064123-8. doi: 10.1093/oso/9780190641221.001.0001.

Structuralism, the view that mathematics is the science of structures, can be characterized as a philosophical response to a general structural turn in modern mathematics. Structuralists aim to understand the ontological, epistemological, and semantical implications of this structural approach in mathematics. Theories of structuralism began to develop following the publication of Paul Benacerraf’s paper ‘What numbers could not be’ in 1965. These theories include non-eliminative approaches, formulated in a background ontology of sui generis structures, such as Stewart Shapiro’s ante rem (...) structuralism and Michael Resnik’s pattern structuralism. In contrast, there are also eliminativist accounts of structuralism, such as Geoffrey Hellman’s modal structuralism, which avoids sui generis structures. These research projects have guided a more systematic focus on philosophical topics related to mathematical structuralism, including the identity criteria for objects in structures, dependence relations between objects and structures, and also, more recently, structural abstraction principles. Parallel to these developments are approaches that describe mathematical structure in category-theoretic terms. Category-theoretic approaches have been further developed using tools from homotopy type theory. Here we find a strong relationship between mathematical structuralism and the univalent foundations project, an approach to the foundations of mathematics based on higher category theory. (shrink)

_Justin Clarke-Doane* * Morality and Mathematics. _ Oxford University Press, 2020. Pp. xx + 208. ISBN: 978-0-19-882366-7 ; 978-0-19-2556806.† †.