M×Φ

Annals of Mathematics and Philosophy

Volume II, number 2, 2024

Special issue : La philosophie mathématique, Mathematical and philosophical inspirations from Brunschvicg to Granger, Part 2

Editors: Gabriella Crocco, Frédéric Jaëck

Volume II, number 2, 2024

This special issue in two volumes is devoted to a certain French tradition in the philosophy of mathematics, a tradition characterized by the tutelary presence of two major figures, Jean Cavaillès (1903–1944) and Albert Lautman (1908–1944), both of whom were shot by the Nazi occupiers for their involvement in the French resistance, and both of whom produced original, albeit unfinished, works in the course of their short lives.

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M×Φ — Annals of Mathematics and Philosophy, 2(2), 2024.

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Introduction

Introduction to the Second Issue

Gabriella Crocco, Frédéric Jaëck pp. 1–2

Presentation of the second volume dedicated to ‘La philosophie mathématique’: Mathematical and Philosophical Inspirations from Brunschvicg to Granger, a special issue devoted to a certain French tradition in the philosophy of mathematics.

Crocco, G., & Jaëck, F. (2024). Introduction to the Second Issue. M×Φ — Annals of Mathematics and Philosophy, 2(2), 1–2.

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Articles

Ce que penser veut dire ? Cavaillès and the problem of the link between philosophy and mathematics

Pascal Bertin pp. 3–28

Our aim in this article is to take the full measure of the formula cited as an epigraph and, through it, to reflect on the problem of the relation between philosophy and mathematics in the work of Jean Cavaillès. In particular, the question will be how to interpret the phrase “by means of mathematics” that appears in this formula. Does this mean that mathematics properly constitutes, for Cavaillès, the framework of expression of thought, or, as we will argue here, that it provides a privileged expression of thought—more “speaking,” though not exclusive?

To approach this problem, we bring to light a double danger: either the philosophical is effaced within the mathematical, or, conversely, the mathematical is subjected to external philosophical norms. The difficulty then consists in situating a theory of science that belongs to the scientific movement while remaining distinct from it. Cavaillès proposes to understand such a theory as an “auto-illumination” of the scientific movement, through which it reveals its own necessity. Mathematics thus appears as an autonomous becoming, governed by necessary sequences, irreducible to any constitutive dependence on the real. It does not coincide with thought, but constitutes its most privileged expression.

Against Ludwig Wittgenstein, Cavaillès maintains the possibility of a theoretical discourse capable of revealing the structure of science. This structure manifests itself in processes of paradigm and thematization, which express the internal dynamics of these sequences. The reference to Baruch Spinoza allows one to conceive this autonomy as a necessary order of ideas. Philosophy thus follows the mathematical movement in order to bring out its necessity, without ever substituting itself for it.

Bertin, P. (2024). Ce que penser veut dire ? Cavaillès and the problem of the link between philosophy and mathematics. M×Φ — Annals of Mathematics and Philosophy, 2(2), 3–28.

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Ce que penser veut dire ?

Pascal Bertin online version, 28 p.

Our aim in this article is to take the full measure of the formula cited as an epigraph and, through it, to reflect on the problem of the relation between philosophy and mathematics in the work of Jean Cavaillès. In particular, the question will be how to interpret the phrase “by means of mathematics” that appears in this formula. Does this mean that mathematics properly constitutes, for Cavaillès, the framework of expression of thought, or, as we will argue here, that it provides a privileged expression of thought—more “speaking,” though not exclusive?

To approach this problem, we bring to light a double danger: either the philosophical is effaced within the mathematical, or, conversely, the mathematical is subjected to external philosophical norms. The difficulty then consists in situating a theory of science that belongs to the scientific movement while remaining distinct from it. Cavaillès proposes to understand such a theory as an “auto-illumination” of the scientific movement, through which it reveals its own necessity. Mathematics thus appears as an autonomous becoming, governed by necessary sequences, irreducible to any constitutive dependence on the real. It does not coincide with thought, but constitutes its most privileged expression.

Against Ludwig Wittgenstein, Cavaillès maintains the possibility of a theoretical discourse capable of revealing the structure of science. This structure manifests itself in processes of paradigm and thematization, which express the internal dynamics of these sequences. The reference to Baruch Spinoza allows one to conceive this autonomy as a necessary order of ideas. Philosophy thus follows the mathematical movement in order to bring out its necessity, without ever substituting itself for it.

Bertin, P. (2024). Ce que penser veut dire ?. M×Φ — Annals of Mathematics and Philosophy, 2(2), online version, 28 p.

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The epistemology of the mathematical “dedans” in Albert Lautman’s early writings

Mario Castellana pp. 29–56

The youthful writings of Albert Lautman are examined, in particular the Rapport Bouglé of 1935, where the major conceptual nucleus of his subsequent research path aimed at entering 'inside' the contents of the sciences are already identified; it is no coincidence that, from the beginning, the philosophical effort has been directed to understand on the one hand the singularity of mathematics and on the other, to clarify 'les enjeux' of the close connection between mathematics and physics, 'l'unité physico-mathématique'. And all this finds its reasons in Lautman's having been a faithful interpreter of Hermann Weyl and of a certain Hilbert; and developing some of their points has allowed him to give an autonomous contribution to the philosophie mathématique, a chapter of epistemological thought produced in the French-speaking area, unique in its kind and still little known.

Castellana, M. (2024). The epistemology of the mathematical “dedans” in Albert Lautman’s early writings. M×Φ — Annals of Mathematics and Philosophy, 2(2), 29–56.

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Gilles-Gaston Granger’s style and duality

Éric Audureau pp. 57–89

After a brief presentation of the original features of Granger's philosophical system, we propose to show that the notion of mathematical style should not be seen as a substitute for the traditional philosophy of mathematics. To this end, we first show how style depends on the principle of duality. We then try to show, by examining it through the sieve of progress in mathematical logic, that the principle of duality does not keep its promises.

Audureau, É. (2024). Gilles-Gaston Granger’s style and duality. M×Φ — Annals of Mathematics and Philosophy, 2(2), 57–89.

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Style et dualité chez Gilles-Gaston Granger

Éric Audureau online version, 34 p.

After a brief presentation of the original features of Granger's philosophical system, we propose to show that the notion of mathematical style cannot claim to be a substitute for the traditional philosophy of mathematics. To this end, we first indicate in what sense style depends on the principle of duality. We then attempt to show, by examining it through the lens of advances in mathematical logic, that the principle of duality does not keep its promises.

Audureau, É. (2024). Style et dualité chez Gilles-Gaston Granger. M×Φ — Annals of Mathematics and Philosophy, 2(2), online version, 34 p.

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Bachelard and Vuillemin, non-Cartesian philosophers? Two criticisms of simple natures

David Thomasette pp. 91–107

Both Bachelard and Vuillemin criticised the Cartesian method, with particular emphasis on the central concept of simple nature. However, despite their apparent convergence, these criticisms turn out to be quite distinct: Bachelard gives these natures an ontological dimension and endows them with absolute self-evidence, while Vuillemin proposes an intuitionist and critical interpretation. We show that the first of these analyses is debatable, and does not really reach Cartesianism, and we measure the philosophical implications of the second, which puts Vuillemin on the track of decisionism.

Thomasette, D. (2024). Bachelard and Vuillemin, non-Cartesian philosophers? Two criticisms of simple natures. M×Φ — Annals of Mathematics and Philosophy, 2(2), 91–107.

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Bachelard et Vuillemin, philosophes non-cartésiens ? Deux critiques des natures simples

David Thomasette online version, 18 p.

Bachelard and Vuillemin both criticised the Cartesian method, with particular emphasis on the central concept of simple nature. Yet, despite their apparent convergence, these criticisms turn out to be quite distinct: Bachelard gives these natures an ontological dimension and endows them with absolute self-evidence, while Vuillemin proposes an intuitionist and critical interpretation. We show that the first of these analyses is debatable and does not truly reach Cartesianism, and we assess the philosophical implications of the second, which sets Vuillemin on the path of decisionism.

Thomasette, D. (2024). Bachelard et Vuillemin, philosophes non-cartésiens ? Deux critiques des natures simples. M×Φ — Annals of Mathematics and Philosophy, 2(2), online version, 18 p.

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History of mathematics and profound mathematical results: the post-Cavaillès debate in French epistemology

Gabriella Crocco pp. 109–128

How can we define a profound mathematical result, and which epistemological criteria should we apply to evaluate the depth of mathematical analysis in the history of mathematics? This article provides a comparative analysis of the works of Gilles-Gaston Granger and Alain Michel on this subject. We argue that the differences in the authors’ perspectives highlight a more fundamental disagreement about how the history of mathematics should be understood. Like Cavaillès, Granger seeks to identify transcendental structures of a kind of creative necessity that are nevertheless incompatible with any form of predictability regarding the evolution of mathematics. In contrast, Michel, along with Brunschvicg and Canguilhem, views mathematical progress as the exploration of a broad range of possibilities. He believes that necessity is merely a retrospective illusion that pays no attention to the details of historical analysis.

Crocco, G. (2024). History of mathematics and profound mathematical results: the post-Cavaillès debate in French epistemology. M×Φ — Annals of Mathematics and Philosophy, 2(2), 109–128.

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L’histoire et la profondeur des résultats mathématiques : le débat post-Cavaillès de l’épistémologie française

Gabriella Crocco online version, 20 p.

How can we define a profound mathematical result, and which epistemological criteria should we apply to evaluate the depth of mathematical analysis in the history of mathematics? This article provides a comparative analysis of the works of Gilles-Gaston Granger and Alain Michel on this subject. We argue that the differences in the authors’ perspectives highlight a more fundamental disagreement about how the history of mathematics should be understood. Like Cavaillès, Granger seeks to identify transcendental structures of a kind of creative necessity that are nevertheless incompatible with any form of predictability regarding the evolution of mathematics. In contrast, Michel, along with Brunschvicg and Canguilhem, views mathematical progress as the exploration of a broad range of possibilities. He believes that necessity is merely a retrospective illusion that pays no attention to the details of historical analysis.

Crocco, G. (2024). L’histoire et la profondeur des résultats mathématiques : le débat post-Cavaillès de l’épistémologie française. M×Φ — Annals of Mathematics and Philosophy, 2(2), online version, 20 p.

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Jean Cavaillès in the legacy of Léon Brunschvicg: mathematical philosophy and the problems of history

Alain Michel pp. 129–156

The philosophy of the history of mathematics expounded by Cavaillès bears a close and contrasting relationship to that set out by Brunschvicg in La Modalité du Jugement. (1897). The activity of scientific judgement is said to be mixed, between (ideal) judgements of interiority and (realistic) judgements of exteriority. The mixed form of the historical activity of knowledge is the modality of the possible. Hence a historical epistemology that claims Kantian idealist filiation and rejects speculative idealism. Cavaillès, a thinker of the creative necessity of mathematical development, reduces the role of intellectual adventure and possibility in its history, and in so doing distances himself from a master to whom Canguilhem would have remained closer. The recent history of mathematics, while paving the way for Kronecker's revenge on the abstract set-theoretical conceptions that inspired Cavaillès's necessitarianism, leads us to reconsider the radicalism that opposed him to Brunschvicg's philosophy of the modality of judgement.

Michel, A. (2024). Jean Cavaillès in the legacy of Léon Brunschvicg: mathematical philosophy and the problems of history. M×Φ — Annals of Mathematics and Philosophy, 2(2), 129–156.

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Mathematics and ‘Depth’: the example of number theory

Alain Michel pp. 157–175

Using examples from number theory, this paper explores the philosophical notion of mathematical “depth” — what makes certain results more profound or significant than others. English translation of « Mathématiques et ‘profondeur’ : l’exemple de la théorie des nombres » (Jean-Toussaint Desanti, une pensée et son site, ed. G. Ravis-Giordani, Fontenay-aux-Roses: ENS Éditions, 2000, pp. 181–199).

Michel, A. (2024). Mathematics and ‘Depth’: the example of number theory. M×Φ — Annals of Mathematics and Philosophy, 2(2), 157–175.

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Letters and Communications

Pierre Cartier (1932–2024)

Frédéric Patras pp. 177–187

A tribute to Pierre Cartier, one of the last universal mathematicians, member of Bourbaki, and a lifelong advocate of the dialogue between mathematics and philosophy.

Patras, F. (2024). Pierre Cartier (1932–2024). M×Φ — Annals of Mathematics and Philosophy, 2(2), 177–187.

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Pierre Cartier (1932–2024)

Frédéric Patras online version, 12 p.

A tribute to Pierre Cartier, one of the last universal mathematicians, member of Bourbaki, and a lifelong advocate of the dialogue between mathematics and philosophy.

Patras, F. (2024). Pierre Cartier (1932–2024). M×Φ — Annals of Mathematics and Philosophy, 2(2), online version, 12 p.

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A few notes on Bill Lawvere’s Intellectual Biography

Alberto Peruzzi pp. 189–198

Some personal and intellectual notes on the life and work of F. William Lawvere, the founder of categorical logic and a deep philosophical thinker about mathematics.

Peruzzi, A. (2024). A few notes on Bill Lawvere’s Intellectual Biography. M×Φ — Annals of Mathematics and Philosophy, 2(2), 189–198.

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