The issues surrounding the Caesar problem are assumed to be inert as far as ongoing mathematics is concerned. This paper aims to correct this impression by spelling out the ways that, in their historical context, Frege's remarks would have had considerable resonance with work that other mathematicians such as Riemann and Dedekind were doing. The search for presentation‐independent characterizations of objects and global definitions was seen as bound up with fundamental methodological questions in complex analysis and number theory.

The issues surrounding the Caesar problem are assumed to be inert as far as ongoing mathematics is concerned. This paper aims to correct this impression by spelling out the ways that, in their historical context, Frege's remarks would have had considerable resonance with work that other mathematicians such as Riemann and Dedekind were doing. The search for presentation‐independent characterizations of objects and global definitions was seen as bound up with fundamental methodological questions in complex analysis and number theory.

This paper sets out to adduce visual evidence for Kroneckerian finitism by making perspicuous some of the insights that buttress Kronecker’s conception of arithmetization as a process aiming at disclosing the arithmetical essence enshrined in analytical formulas, by spotting discrete patterns through algorithmic fine-tuning. In the light of a fairly tractable case study, it is argued that Kronecker’s main tenet in philosophy of mathematics is not so much an ontological as a methodological one, inasmuch as highly demanding requirements regarding mathematical (...) understanding prevail over mere preemptive reductionism to whole numbers. (shrink)

When the traditional distinction between a mathematical concept and a mathematical intuition is tested against examples taken from the real history of mathematics one can observe the following interesting phenomena. First, there are multiple examples where concepts and intuitions do not well fit together; some of these examples can be described as “poorly conceptualised intuitions” while some others can be described as “poorly intuited concepts”. Second, the historical development of mathematics involves two kinds of corresponding processes: poorly conceptualised intuitions are (...) further conceptualised while poorly intuited concepts are further intuited. In this paper I study this latter process in mathematics during the twentieth century and, more specifically, show the role of set theory and category theory in this process. I use this material for defending the following claims: (1) mathematical intuitions are subject to historical development just like mathematical concepts; (2) mathematical intuitions continue to play their traditional role in today's mathematics and will plausibly do so in the foreseeable future. This second claim implies that the popular view, according to which modern mathematical concepts, unlike their more traditional predecessors, cannot be directly intuited, is not justified. (shrink)

This article examines the research of Louis J. Mordell on the Diophantine equation y2-k=x3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$y^2-k=x^3$$\end{document} as it appeared in one of his first papers, published in 1914. After presenting a number of elements relating to Mordell’s mathematical youth and his (problematic) writing, we analyze the 1914 paper by following the three approaches he developed therein, respectively, based on the quadratic reciprocity law, on ideal numbers, and on binary cubic forms. This analysis allows (...) us to describe many of the difficulties in reading and understanding Mordell’s proofs, difficulties which we make explicit and comment on in depth. (shrink)

Dans cet article, je considère la pratique et la conception de la ri­gueur chez Richard Dedekind qui se dégagent de l’étude d’une sélection de ses travaux les plus importants. Une analyse des mentions multiples de réquisits de rigueur dans les textes de Dedekind amène à constater qu’il lie très étroi­tement la rigueur à la généralité. La première partie de l’article donne à voir les liens serrés tissés par Dedekind entre généralité et rigueur, dans sa théorie des fonctions algébriques co-écrite avec (...) H. Weber, ainsi que dans ses travaux fondationnels et dans ses travaux de théorie des nombres. Dans la seconde partie, j’examine les critères de rigueur qui apparaissent dans la pratique ma­thématique de Dedekind. Je discute l’idéal logique de rigueur dans l’essai de Dedekind sur les entiers naturels, étudié par M. Detlefsen sous l’appellation « Dedekind’s principle » ; puis je m’intéresse à la stratégie de Dedekind pour arithmétiser les mathématiques afin de mettre en évidence qu’il ne s’agit pas d’une approche guidée par un principe purement logique. Ainsi, l’idéal logique de rigueur apparaît comme intimement lié à la pratique d’une autre norme épistémique : la généralité, en lien avec la quête, par Dedekind, de définitions et preuves générales. Dans la dernière partie, j’analyse la demande de généra­lité et la pluralité de conceptions de la généralité que recouvre cette demande, et termine en mettant en avant la relation des définitions aux preuves et de quelle manière une définition générale se pose en condition de rigueur dans les mathématiques dedekindiennes. (shrink)

Dans cet article, je considère la pratique et la conception de la ri­gueur chez Richard Dedekind qui se dégagent de l’étude d’une sélection de ses travaux les plus importants. Une analyse des mentions multiples de réquisits de rigueur dans les textes de Dedekind amène à constater qu’il lie très étroi­tement la rigueur à la généralité. La première partie de l’article donne à voir les liens serrés tissés par Dedekind entre généralité et rigueur, dans sa théorie des fonctions algébriques co-écrite avec (...) H. Weber, ainsi que dans ses travaux fondationnels et dans ses travaux de théorie des nombres. Dans la seconde partie, j’examine les critères de rigueur qui apparaissent dans la pratique ma­thématique de Dedekind. Je discute l’idéal logique de rigueur dans l’essai de Dedekind sur les entiers naturels, étudié par M. Detlefsen sous l’appellation « Dedekind’s principle » ; puis je m’intéresse à la stratégie de Dedekind pour arithmétiser les mathématiques afin de mettre en évidence qu’il ne s’agit pas d’une approche guidée par un principe purement logique. Ainsi, l’idéal logique de rigueur apparaît comme intimement lié à la pratique d’une autre norme épistémique : la généralité, en lien avec la quête, par Dedekind, de définitions et preuves générales. Dans la dernière partie, j’analyse la demande de généra­lité et la pluralité de conceptions de la généralité que recouvre cette demande, et termine en mettant en avant la relation des définitions aux preuves et de quelle manière une définition générale se pose en condition de rigueur dans les mathématiques dedekindiennes. (shrink)

Dans cet article, je considère la pratique et la conception de la ri­gueur chez Richard Dedekind qui se dégagent de l’étude d’une sélection de ses travaux les plus importants. Une analyse des mentions multiples de réquisits de rigueur dans les textes de Dedekind amène à constater qu’il lie très étroi­tement la rigueur à la généralité. La première partie de l’article donne à voir les liens serrés tissés par Dedekind entre généralité et rigueur, dans sa théorie des fonctions algébriques co-écrite avec (...) H. Weber, ainsi que dans ses travaux fondationnels et dans ses travaux de théorie des nombres. Dans la seconde partie, j’examine les critères de rigueur qui apparaissent dans la pratique ma­thématique de Dedekind. Je discute l’idéal logique de rigueur dans l’essai de Dedekind sur les entiers naturels, étudié par M. Detlefsen sous l’appellation « Dedekind’s principle » ; puis je m’intéresse à la stratégie de Dedekind pour arithmétiser les mathématiques afin de mettre en évidence qu’il ne s’agit pas d’une approche guidée par un principe purement logique. Ainsi, l’idéal logique de rigueur apparaît comme intimement lié à la pratique d’une autre norme épistémique : la généralité, en lien avec la quête, par Dedekind, de définitions et preuves générales. Dans la dernière partie, j’analyse la demande de généra­lité et la pluralité de conceptions de la généralité que recouvre cette demande, et termine en mettant en avant la relation des définitions aux preuves et de quelle manière une définition générale se pose en condition de rigueur dans les mathématiques dedekindiennes. (shrink)

The general framework of this paper is a reformulation of Hilbert’s program using the theory of locales, also known as formal or point-free topology [P.T. Johnstone, Stone Spaces, in: Cambridge Studies in Advanced Mathematics, vol. 3, 1982; Th. Coquand, G. Sambin, J. Smith, S. Valentini, Inductively generated formal topologies, Ann. Pure Appl. Logic 124 71–106; G. Sambin, Intuitionistic formal spaces–a first communication, in: D. Skordev , Mathematical Logic and its Applications, Plenum, New York, 1987, pp. 187–204]. Formal topology presents a (...) topological space, not as a set of points, but as a logical theory which describes the lattice of open sets. The application to Hilbert’s program is then the following. Hilbert’s ideal objects are represented by points of such a formal space. There are general methods to “eliminate” the use of points, close to the notion of forcing and to the “elimination of choice sequences” in intuitionist mathematics, which correspond to Hilbert’s required elimination of ideal objects. This paper illustrates further this general program on the notion of valuations. They were introduced by Dedekind and Weber [R. Dedekind, H. Weber, Theorie des algebraischen Funktionen einer Veränderlichen, J. de Crelle t. XCII 181–290] to give a rigorous presentation of Riemann surfaces. It can be argued that it is one of the first example in mathematics of point-free representation of spaces [N. Bourbaki, Eléments de Mathématique. Algèbre commutative, Hermann, Paris, 1965, Chapitre 7]. It is thus of historical and conceptual interest to be able to represent this notion in formal topology. (shrink)

C.F Gauss’s computational work in number theory attracted renewed interest in the twentieth century due to, on the one hand, the edition of Gauss’s Werke, and, on the other hand, the birth of the digital electronic computer. The involvement of the U.S. American mathematicians Derrick Henry Lehmer and Daniel Shanks with Gauss’s work is analysed, especially their continuation of work on topics as arccotangents, factors of n2 + a2, composition of binary quadratic forms. In general, this strand in Gauss’s reception (...) is part of a more general phenomenon, i.e. the influence of the computer on mathematics and one of its effects, the reappraisal of mathematical exploration. (shrink)

In 1837, Dirichlet proved that there are infinitely many primes in any arithmetic progression in which the terms do not all share a common factor. We survey implicit and explicit uses ofDirichlet characters in presentations of Dirichlet’s proof in the nineteenth and early twentieth centuries, with an eye toward understanding some of the pragmatic pressures that shaped the evolution of modern mathematical method.

On a traditional view, the primary role of a mathematical proof is to warrant the truth of the resulting theorem. This view fails to explain why it is very often the case that a new proof of a theorem is deemed important. Three case studies from elementary arithmetic show, informally, that there are many criteria by which ordinary proofs are valued. I argue that at least some of these criteria depend on the methods of inference the proofs employ, and that (...) standard models of formal deduction are not well-equipped to support such evaluations. I discuss a model of proof that is used in the automated deduction community, and show that this model does better in that respect. (shrink)

Philosophical concerns rarely force their way into the average mathematician’s workday. But, in extreme circumstances, fundamental questions can arise as to the legitimacy of a certain manner of proceeding, say, as to whether a particular object should be granted ontological status, or whether a certain conclusion is epistemologically warranted. There are then two distinct views as to the role that philosophy should play in such a situation. On the first view, the mathematician is called upon to turn to the counsel (...) of philosophers, in much the same way as a nation considering an action of dubious international legality is called upon to turn to the United Nations for guidance. After due consideration of appropriate regulations and guidelines (and, possibly, debate between representatives of different philosophical factions), the philosophers render a decision, by which the dutiful mathematician abides. Quine was famously critical of such dreams of a ‘first philosophy.’ At the opposite extreme, our hypothetical mathematician answers only to the subject’s internal concerns, blithely or brashly indifferent to philosophical approval. What is at stake to our mathematician friend is whether the questionable practice provides a proper mathematical solution to the problem at hand, or an appropriate mathematical understanding; or, in pragmatic terms, whether it will make it past a journal referee. In short, mathematics is as mathematics does, and the philosopher’s task is simply to make sense of the subject as it evolves and certify practices that are already in place. In his textbook on the philosophy of mathematics (Shapiro, 2000), Stewart Shapiro characterizes this attitude as ‘philosophy last, if at all.’. (shrink)

By the middle of the nineteenth century, it had become clear to mathematicians that the study of finite field extensions of the rational numbers is indispensable to number theory, even if one’s ultimate goal is to understand properties of diophantine expressions and equations in the ordinary integers. It can happen, however, that the “integers” in such extensions fail to satisfy unique factorization, a property that is central to reasoning about the ordinary integers. In 1844, Ernst Kummer observed that unique factorization (...) fails for the cyclotomic integers with exponent 23, i.e. the ring Z[ζ] of integers of the field Q(ζ), where ζ is a primitive twenty-third root of unity. In 1847, he published his theory of “ideal divisors” for cyclotomic integers with prime exponent. This was to remedy the situation by introducing, for each such ring of integers, an enlarged domain of divisors, and showing that each integer factors uniquely as a product of these. He did not actually construct these integers, but, rather, showed how one could characterize their behavior qua divisibility in terms of ordinary operations on the associated ring of integers. (shrink)

This survey article describes Frege's celebrated foundational work against the context of other late nineteenth century approaches to introducing mathematically novel "extension elements" within both algebra and geometry.