In the early 1920s, the German mathematician David Hilbert (1862–1943) put forward a new proposal for the foundation of classical mathematics which has come to be known as Hilbert's Program. It calls for a formalization of all of mathematics in axiomatic form, together with a proof that this axiomatization of mathematics is consistent. The consistency proof itself was to be carried out using only what Hilbert called “finitary” methods. The special epistemological character of finitary reasoning then yields the required justification (...) of classical mathematics. Although Hilbert proposed his program in this form only in 1921, various facets of it are rooted in foundational work of his going back until around 1900, when he first pointed out the necessity of giving a direct consistency proof of analysis. Work on the program progressed significantly in the 1920s with contributions from logicians such as Paul Bernays, Wilhelm Ackermann, John von Neumann, and Jacques Herbrand. It was also a great influence on Kurt Gödel, whose work on the incompleteness theorems were motivated by Hilbert's Program. Gödel's work is generally taken to show that Hilbert's Program cannot be carried out. It has nevertheless continued to be an influential position in the philosophy of mathematics, and, starting with the work of Gerhard Gentzen in the 1930s, work on so-called Relativized Hilbert Programs have been central to the development of proof theory. (shrink)

Unsere These lautet, dass die Geschichte des logischen Empirismus bisher nicht in ihrer ganzen Komplexität dargestellt wurde. Es herrscht das Bild vor, dass vor allem der Wiener Kreis die wissenschaftliche Philosophie seiner Zeit dominiert habe. In Wirklichkeit waren Hans Reichenbach und die Philosophen und Wissenschaftler in seiner Gruppe mehr als nur geistige Verwandte der Wiener logischen Empiristen. Die Berliner Gruppe war ein gleichberechtigter Partner bei der Verbreitung wissenschaftlicher Philosophie im deutschsprachigen Raum um 1930 und schlug dabei durchaus einen individuellen Weg (...) ein. Reichenbach hat daher auch ausdrücklich die Eigenständigkeit der Berliner Gruppe innerhalb des logischen Empirismus verteidigt (Hoffmann 1994, 26). Dabei kämpfte er nicht einfach für Gleichberechtigung mit dem Wiener Kreis. Reichenbach beanspruchte sogar die Priorität der Initiative. (shrink)

In the early 1920s, Hans Reichenbach and Kurt Lewin presented two topological accounts of time that appear to be interrelated in more than one respect. Despite their different approaches, their underlying idea is that time order is derived from specific structural properties of the world. In both works, moreover, the notion of genidentity--i.e., identity through or over time--plays a crucial role. Although it is well known that Reichenbach borrowed this notion from Kurt Lewin, not much has been written about their (...) relationship, nor about the way Lewin implemented this notion in his own work in order to ground his topology. This paper examines these two early versions of the topology of time, and follows the extent of Lewin’s influence on Reichenbach’s proposal. (shrink)

This paper gives a survey of David Hilbert's (1862–1943) changing attitudes towards logic. The logical theory of the Göttingen mathematician is presented as intimately linked to his studies on the foundation of mathematics. Hilbert developed his logical theory in three stages: (1) in his early axiomatic programme until 1903 Hilbert proposed to use the traditional theory of logical inferences to prove the consistency of his set of axioms for arithmetic. (2) After the publication of the logical and set-theoretical paradoxes by (...) Gottlob Frege and Bertrand Russell it was due to Hilbert and his closest collaborator Ernst Zermelo that mathematical logic became one of the topics taught in courses for Göttingen mathematics students. The axiomatization of logic and set-theory became part of the axiomatic programme, and they tried to create their own consistent logical calculi as tools for proving consistency of axiomatic systems. (3) In his struggle with intuitionism, represented by L. E. J. Brouwer and his advocate Hermann Weyl, Hilbert, assisted by Paul Bemays, created the distinction between proper mathematics and meta-mathematics, the latter using only finite means. He considerably revised the logical calculus of thePrincipia Mathematica of Alfred North Whitehead and Bertrand Russell by introducing the ε-axiom which should serve for avoiding infinite operations in logic. (shrink)

Recently, Michael Friedman has claimed that virtually all the seeds of Hempel’s philosophical development trace back to his early encounter with the Vienna Circle (Friedman 2003, 94). As opposed, however, to Friedman’s view of the principal early influences on Hempel, we shall see that those formative influences originated rather with the Berlin Group. Hempel, it is true, spent the fall term of 1929 as a student at the University of Vienna, and, thanks to a letter of recommendation from Hans Reichenbach, (...) he even attended some sessions of the Vienna Circle. But he spent much less time in Vienna than in Berlin, where he studied under Reichenbach from 1926 till 1933 and wrote a dissertation on probability, Reichenbach’s specialty. Hempel also attended seminars conducted by Walter Dubislav, another member of the Berlin Group. (shrink)

Au terme des Prolégomènes, Husserl formule son idée de la logique pure en la structurant sur deux niveaux: l'un, supérieur, de la logique formelle fondé transcendantalement et d'un point de vue épistémologique par l'autre, inférieur, d'une morphologie des catégories. Seul le second de ces deux niveaux est traité dans les Recherches logiques, tandis que les travaux théoriques en logique formelle menés par Husserl à la même époque en paraissent plutôt indépendants. Cet article est consacré à ces travaux tels que recueillis (...) dans les appendices VI-X du volume 12 des Husserliana. Mettant en évidence la théorie de la signification qui les sous-tend par le biais d'une analyse de la question dite de l'extension des systèmes d'axiomes et de sa résolution au moyen d'une notion de complétude, son objectif est d'expliciter les modalités de l'intégration de la logique formelle dans l'idée husserlienne de la logique pure au tournant du xx siècle.When formulating his idea of pure logic in the Prole.. (shrink)

The article introduces and discusses an unpublished manuscript by Edmund Husserl, conserved at the Husserl-Archives Leuven with signature K I 26, pp. 73a–73b. The article is followed by the text of the manuscript in German and in an English translation. The manuscript, titled “The Transition through the Impossible” ( Der Durchgang durch das Unmögliche ), was part of the material Husserl used for his 1901 Doppelvortrag in Göttingen. In the manuscript, the impossible is characterized as the “sphere of objectlessness” ( (...) Sphäre der Gegenstandslosigkeit ) and Husserl addresses the question whether and when it is warranted to perform a transition through the impossible to obtain valid results for the sphere of objectivity. (shrink)

ArgumentThis article gives the background to a public lecture delivered in Hebrew by Edmund Landau at the opening ceremony of the Hebrew University in Jerusalem in 1925. On the surface, the lecture appears to be a slightly awkward attempt by a distinguished German-Jewish mathematician to popularize a few number-theoretical tidbits. However, quite unexpectedly, what emerges here is Landau's personal blend of Zionism, German nationalism, and the proud ethos of pure, rigorous mathematics – against the backdrop of the situation of Germany (...) after World War I. Landau's Jerusalem lecture thus shows how the Zionist cause was inextricably linked to, and determined by political agendas that were taking place in Europe at that time. The lecture stands in various historical contexts - Landau's biography, the history of Jewish scientists in the German Zionist movement, the founding of the Hebrew University in Jerusalem, and the creation of a modern Hebrew mathematical language. This article provides a broad historical introduction to the English translation, with commentary, of the original Hebrew text. (shrink)

In his ontological works Kurt Grelling tries to give a rigorous analysis of the foundations of the so-called Gestalt-psychology. Gestalten are peculiar emergent qualities, ontologically dependent on their foundations, but nonetheless non reducible to them. Grelling shows that this concept, as used in psychology and ontology, is often ambiguous. He distinguishes two important meanings in which the word “Gestalt” is used: Gestalten as structural aspects available to transposition and Gestalten as causally self-regulating wholes. Gestalten in the first meaning are, according (...) to Grelling, “equivalence classes of correspondences”, while Gestalten as self-regulating wholes have more to do with relations of ontological dependence. Grelling’s clarification of the concept of Gestalt is doubtless an excellent piece of philosophical analysis, but at the end of the day it turns out that his analysis captures at best only a part of intuitions traditionally connected with the notion of Gestalt. (shrink)

Jakob Friedrich Fries (1773–1843) was the most prolific German philosopher of science in the nineteenth century who strived to synthesize Kant’s philosophical foundation of science and mathematics and the needs or practised science and mathematics in order to gain more comprehensive conceptual frameworks and greater methodological flexibility for those two disciplines. His original contributions anticipated later developments, to some extent, though they received comparatively little notice in the later course of the nineteenth century—a fate which partly can be explained by (...) the unfortunate development of the so-called ‘First Friesian School,’ founded by E. F. Apelt, M. J. Schleiden and O. X. Schlömilch. This situation changed temporarily when Leonard Nelson (1882–1927) arrived on the philosophical stage and founded a second, so-called, ‘New Friesian School’ in 1903. In the following two decades, Fries’ specific transformation of Kantian philosophy gained influence within the vigorous discussions about ‘new’ foundations of mathematics and, thus, also played a role within the Berlin Group surrounding Hans Reichenbach, though his work had no direct impact on the philosophy of physics being expounded therein. -/- This essay will first outline some characteristics of Fries’ development of the Kantian approach. Then it will point out the limited impact of the ‘New Friesian School’ on the Berlin Group, while highlighting some missed chances for fruitful exchange. As the originality of this school and its importance for the development of logic and philosophy of mathematics—by and large merits of its early members Walter Dubislav and Kurt Grelling —is dealt with in separate chapters of this volume, and elsewhere, this article will focus on what Fries called the ‘mathematical philosophy of nature’ (i. e. the philosophical foundations of physics). More specifically, it will show how the New Friesian School reacted to Einstein’s theories of relativity, in a way that contrasts with the approach of the Berlin Group. This discussion about relativity will also be used to reveal different understandings of the nature of ‘scientific philosophy’ in general, as well as different models of how philosophy and the empirical sciences should interact. (shrink)