Strict finitism is a minority view in the philosophy of mathematics. In this paper, we develop a strict finite axiomatic system for geometric constructions in which only constructions that are executable by simple tools in a small number of steps are permitted. We aim to demonstrate that as far as the applications of synthetic geometry to real-world constructions are concerned, there are viable strict finite alternatives to classical geometry where by one can prove analogs to fundamental results in classical geometry. (...) We consider this as one of many early steps investigating the extent to which strict finite foundations can be developed for the application of mathematics to the real-world. (shrink)

This paper is an amalgam of physics and mathematical logic. It contains an elementary axiomatization of spacetime in terms of the primitive concepts of particle, signal, and transmission and reception. In the elementary language formed with these predicates we state AxiomsE, C, andU, which are naturally interpretable as basic physical properties of particles and signals. We then determine all mathematical models of this axiom system; these represent certain generalizations of the standard model. Also, the automorphism groups of the models are (...) determined. Finally we give another physical model and discuss the philosophical implications. (shrink)

Je propose d’analyser une pratique de la recherche en mathématiques constructives, celle qui consiste à reformuler constructivement les théories physiques. Je discute plus précisément trois aspects de cette pratique. Je montre d’abord que celle-ci a la particularité d’être motivée par des considérations philosophiques et comment la physique est utilisée pour arbitrer un débat de philosophie des mathématiques entre constructivisme et classicisme. Ensuite, j’identifie la méthodologie de la recherche en mathématiques que cette pratique implique et montre qu’il s’agit, selon une terminologie (...) empruntée à Poincaré, d’une méthodologie de « logiciens ». Enfin, je montre que dans cette pratique, les théories physiques ont un rôle heuristique sur le développement des mathématiques constructives. Elles permettent avec succès de stimuler la recherche d’énoncés constructifs et d’orienter la recherche en mathématiques constructives vers de nouveaux domaines. (shrink)

Infinity is not what it seems. Infinity is commonly assumed to be a logical concept, reliable for conducting mathematics, describing the Universe, and understanding the divine. Most of us are educated to take for granted that there exist infinite sets of numbers, that lines contain an infinite number of points, that space is infinite in expanse, that time has an infinite succession of events, that possibilities are infinite in quantity, and over half of the world’s population believes in a divine (...) Creator infinite in knowledge, power, and benevolence. -/- According to this treatise, such assumptions are mistaken. In reality, to be is to be finite. The implications of this assessment are profound: the Universe and even God must necessarily be finite. -/- The author makes a compelling case against infinity, refuting its most prominent advocates. Any defense of the infinite will find it challenging to answer the arguments laid out in this book. But regardless of the reader’s position, Forever Finite offers plenty of thought-provoking material for anyone interested in the subject of infinity from the perspectives of philosophy, mathematics, science, and theology. (shrink)

There are good reasons to think there is a universal, fundamental length, specifically, at the order of the Planck length. If this holds, we then have an empirical answer for Zeno’s paradox of Achilles and the tortoise, a potential impasse in the second premise of the kalam cosmological argument, and creation ex nihilo. In this paper, I establish metaphysical, empirical, and epistemic reasons suggesting there is a universal, fundamental length. Along the way, I propose a “contingent necessity” for such a (...) notion. I then detail how a universal, fundamental length is a preferred solution for issues –. (shrink)

Richard Sorabji here takes time as his central theme, exploring fundamental questions about its nature: Is it real or an aspect of consciousness? Did it begin along with the universe? Can anything escape from it? Does it come in atomic chunks? In addressing these and myriad other issues, Sorabji engages in an illuminating discussion of early thought about time, ranging from Plato and Aristotle to Islamic, Christian, and Jewish medieval thinkers. Sorabji argues that the thought of these often negelected philosophers (...) about the subject is, in many cases, more complete than that of their more recent counterparts. “Splendid. . . . The canvas is vast, the picture animated, the painter nonpareil. . . . Sorabji’s work will encourage more adventurers to follow him to this fascinating new-found land.”—Jonathan Barnes, Times Literary Supplement “One of the most important works in the history of metaphysics to appear in English for a considerable time. No one concerned with the problems with which it deals either as a historian of ideas or as a philosopher can afford to neglect it.”—Donald MacKinnon, Scottish Journal of Theology “Unusually readable for such scholarly content, the book provides in rich and cogent terms a lively and well-balanced discussion of matters of concern to a wide academic audience.”— Choice. (shrink)

Numerous approaches to a quantum theory of gravity posit fundamental ontologies that exclude spacetime, either partially or wholly. This situation raises deep questions about how such theories could relate to the empirical realm, since arguably only entities localized in spacetime can ever be observed. Are such entities even possible in a theory without fundamental spacetime? How might they be derived, formally speaking? Moreover, since by assumption the fundamental entities cannot be smaller than the derived and so cannot ‘compose’ them in (...) any ordinary sense, would a formal derivation actually show the physical reality of localized entities? We address these questions via a survey of a range of theories of quantum gravity, and generally sketch how they may be answered positively. (shrink)

In this paper I present the Discrete Space-Time Thesis, in a way which enables me to defend it against various well-known objections, and which extends to the discrete versions of Special and General Relativity with only minor difficulties. The point of this presentation is not to convince readers that space-time really is discrete but rather to convince them that we do not yet know whether or not it is. Having argued that it is an open question whether or not space-time (...) is discrete, I then turn to some possible empirical evidence, which we do not yet have. This evidence is based on some slight differences between commonly occurring differential equations and their discrete analogs. (shrink)

Während Cantor die Mathematik auf den Begriff des Aktual-Unendlichen abgestützt hat, legten Brouwer und die Konstruktivisten das Potentiell-Unendliche zugrunde. Noch radikaler ist die Philosophie des Strikten Finitismus, welche vom Natürlich-Unendlichen ausgeht, d.h. der Vorstellung des Unüberblickbaren, Unausführbaren, Unerreichbaren. Darauf aufbauend liegen bereits strikt finitistische Rekonstruktionen von Arithmetik, Geometrie, Analysis und Mengenlehre vor. Untersuchungen zur ontogenetischen und historischen Entwicklung der Unendlichkeitsbegriffe untermauern zusätzlich die Philosophie des Strikten Finitismus.

The authors aim to reinstate a spirit of philosophical enquiry in physics. They abandon the intuitive continuum concepts and build up constructively a combinatorial mathematics of process. This radical change alone makes it possible to calculate the coupling constants of the fundamental fields which? via high energy scattering? are the bridge from the combinatorial world into dynamics. The untenable distinction between what is?observed?, or measured, and what is not, upon which current quantum theory is based, is not needed. If we (...) are to speak of mind, this has to be present? albeit in primitive form? at the most basic level, and not to be dragged in at one arbitrary point to avoid the difficulties about quantum observation. There is a growing literature on information-theoretic models for physics, but hitherto the two disciplines have gone in parallel. In this book they interact vitally. (shrink)

This is an introduction to, and survey of, the constructive approaches to pure mathematics. The authors emphasise the viewpoint of Errett Bishop's school, but intuitionism. Russian constructivism and recursive analysis are also treated, with comparisons between the various approaches included where appropriate. Constructive mathematics is now enjoying a revival, with interest from not only logicans but also category theorists, recursive function theorists and theoretical computer scientists. This account for non-specialists in these and other disciplines.

A spatial logic is a formal language interpreted over any class of structures featuring geometrical entities and relations, broadly construed. In the past decade, spatial logics have attracted much attention in response to developments in such diverse fields as Artificial Intelligence, Database Theory, Physics, and Philosophy. The aim of this handbook is to create, for the first time, a systematic account of the field of spatial logic. The book comprises a general introduction, followed by fourteen chapters by invited authors. Each (...) chapter provides a self-contained overview of its topic, describing the principal results obtained to date, explaining the methods used to obtain them, and listing the most important open problems. Jointly, these contributions constitute a comprehensive survey of this rapidly expanding subject. (shrink)

A book on the notion of fundamental length, covering issues in the philosophy of math, metaphysics, and the history and the philosophy of modern physics, from classical electrodynamics to current theories of quantum gravity. Published (2014) in Cambridge University Press.

This book presents a detailed analysis of three ancient models of spatial magnitude, time, and local motion. The Aristotelian model is presented as an application of the ancient, geometrically orthodox conception of extension to the physical world. The other two models, which represent departures from mathematical orthodoxy, are a "quantum" model of spatial magnitude, and a Stoic model, according to which limit entities such as points, edges, and surfaces do not exist in (physical) reality. The book is unique in its (...) discussion of these ancient models within the context of later philosophical, scientific, and mathematical developments. (shrink)

In this paper several arguments are discussed and evaluated concerning the possibility of discrete space and time.

The distinction between the discrete and the continuous lies at the heart of mathematics. Discrete mathematics (arithmetic, algebra, combinatorics, graph theory, cryptography, logic) has a set of concepts, techniques, and application areas largely distinct from continuous mathematics (traditional geometry, calculus, most of functional analysis, differential equations, topology). The interaction between the two – for example in computer models of continuous systems such as fluid flow – is a central issue in the applicable mathematics of the last hundred years. This article (...) explains the distinction and why it has proved to be one of the great organizing themes of mathematics. (shrink)