Carlo Ierna

The concept of a Mannigfaltigkeit in Husserl has been given various interpretations, due to its shifting role in his works. Many authors have been misled by this term, placing it in the context of Husserl’s early period in Halle, while writing the Philosophy of Arithmetic, as a friend and colleague of Georg Cantor.Yet at the time, Husserl distanced himself explicitly from Cantor’s definition and rather took Bernhard Riemann as example, having studied and lectured extensively on Riemann’s theories of space. Husserl’s Mannigfaltigkeitslehre would then not be a Cantorian set-theory, but come rather closer to topology. Then, in the Prolegomena, Husserl introduces the idea of a pure Mannigfaltigkeitslehre as a meta-theoretical enterprise which studies the relations among theories, e.g. how to derive or found one upon another. When Husserl announces that in fact the best example of such a pure theory of manifolds is what is actually practiced in mathematics, this sounds slightly misleading. The pure theory of theories cannot simply be the mathematics underlying topology, but should rather be considered as a mathesis universalis. Indeed, while this might not have been fully clear yet in 1900/1901, Husserl will explicitly tie together the notions of pure theory of manifolds and mathesis universalis. The mathesis universalis in this sense is formal, a priori and analytic, as theory of theory in general. It is an analysis of the highest categories of meaning and their correlative categories of objects. In my paper I try to understand the development of the notion of Mannigfaltigkeit in Husserl’s thought from its mathematical beginnings to its later central philosophical role, taking into account the mathematical background and context of Husserl’s own development.

In this article I will analyse Husserl’s conception of the infinite as ex- pressed in the paragraph Unendliche Mengen of his Philosophie der Arithmetik (PA). I will give a short exposition on his distinction be- tween proper and symbolic presentations and then proceed to the logi- cal distinctions that Husserl makes between finite and infinite symbolic collections. Subsequently (in section 2.3), I will discuss Husserl’s addition of surrogate presentations as a sub-type of symbolic presentations in his short treatise Zur Logik der Zeichen (Semiotik). In this later text (which was originally intended as an appendix to the never published second volume of the PA) Husserl gives a more detailed account of how we can conceive of the infinite, using surrogate presentations.

Franz Brentano is not usually associated with mathematics. Generally, only Brentano’s discussion of the continuum and his critique of the mathematical accounts of it is treated in the literature. It is this detailed critique which suggests that Brentano had more than a superficial familiarity with mathematics. Indeed, considering the authors and works quoted in his lectures, Brentano appears well-informed and quite interested in the mathematical research of his time. I specifically address his lectures here as there is much less to be found about mathematics in his published works. Besides Brentano’s own work, it is quite remarkable to see that practically all of his better-known students sooner or later produced a work on the philosophy of mathematics. This also encourages the supposition not just of a common interest in the matter, but of a common theoretical core. All this prompts the question: Can we speak of a Brentanist philosophy of mathematics?

Among the various lecture courses that Edmund Husserl held during his time as a Privatdozent at the University of Halle (1887-1901), there was one on "Ausgewählte Fragen aus der Philosophie der Mathematik" (Selected Questions from the Philosophy of Mathematics), which he gave twice, once in the WS 1889/90 and again in WS 1890/91. As Husserl reports in his letter to Carl Stumpf of February 1890, he lectured mainly on “spatial-logical questions” and gave an extensive critique of the Riemann-Helmholtz theories. Indeed, in K I 28 many lectures on this subject can be found, which are for the greater part published in Husserliana XXI. The lecture contained in K I 28/4-12 at the Husserl-Archives Leuven, however, was left out of the selection, because the lecture contained “an analysis of the concept of number” whose content is “already known” from the Philosophie der Arithmetik. Indeed, since the lecture is from the WS 1889/90, the manuscript allows a glimpse of Husserl’s ideas halfway between his Habilitationsschrift (1887) and the Philosophie der Arithmetik (1891). Among other things, in this lecture we find the first documented use of the terms "Gestalt" and "Gestaltmoment" in Husserl.

Among the various lecture courses that Edmund Husserl held during his time as a Privatdozent at the University of Halle (1887-1901), there was one on Ausgewählte Fragen aus der Philosophie der Mathematik (Selected Questions from the Philosophy of Mathematics), which he gave twice, once in the WS 1889/90 and again in WS 1890/91. As Husserl reports in his letter to Carl Stumpf of February 1890, he lectured mainly on “spatial-logical questions” and gave an extensive critique of the Riemann-Helmholtz theories. Indeed, in K I 28 many lectures on this subject can be found, which are for the greater part published in Husserliana XXI. The lecture contained in K I 28/4-12 at the Husserl-Archives Leuven, however, was left out of the selection, because the lecture contained “an analysis of the concept of number” whose content is “already known” from the Philosophie der Arithmetik. Indeed, since the lecture is from the WS 1889/90, the manuscript allows a glimpse of Husserl’s ideas halfway between his Habilitationsschrift (1887) and the Philosophie der Arithmetik (1891). From an exam- ple Husserl gives in the lecture: “Der wievielte Januar ist heute?” (The how-many-th of January is it today?), it can be estimated to be from January 1890, placing it in close relation to the letter to Stumpf and the views and doubts expressed therein. The bundle of papers K I 28 is wrapped in a blue cover, bearing only “Vor- lesungen” (Lectures) as a title. The lecture “On the concept of Number” in K I 28/4-12 is contained again in a separate cover, without any title. As in the case of most of his lectures, Husserl folded the paper in half, using the right half as a margin for annotations. Before the lecture there is a single page (K I 28/3) with some annotations on the treatment of imaginary numbers as assumptions in calculation. This text is published here as an Appendix to the lecture, because, while it is not part of the lecture itself, it is closely related to the subjects discussed therein.

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

The article examines the development of Husserl’s early philosophy from his Habilitationsschrift to the Philosophie der Arithmetik . An attempt will be made at reconstructing the lost Habilitationsschrift . The examined sources show that the original version of the Habilitationsschrift was by far broader than the printed version, and included most topics of the PA. The article contains an extensive and detailed comparison of these texts to illustrate the changes in Husserl’s position before and after February 1890. This date is taken as a turning point in his development, because of Husserl’s announcement in a letter to Carl Stumpf that he was mistaken in his basic assumption, i.e. that the analysis of the concept of Anzahl would yield a foundation for arithmetic. Some interesting conclusions in this respect can also be drawn from an unpublished lecture that Husserl held in the WS 1889/90, in which he anticipates aspects of his position hitherto deemed to belong to the last phases of the PA

In this paper I will discuss Edmund Husserl’s critique of Franz Brentano’s interpretation of categorical judgments as Double Judgments (Doppelurteile). This will be developed mostly as an internal critique, within the framework of the school of Brentano, and not through a direct contrast with Husserl’s own theory of judgment, as presented e.g. in the Fifth Investigation. Already during the 1890s Husserl overcame the psychologistic aspects of Brentano’s approach, advocating the importance of analysing the logical structure underlying language independently from psychology. Moreover, Husserl’s critique seems to be also applicable to Bertrand Russell’s analysis, which shares an important aspect of Brentano’s theory. I will try to avoid going too deep into the various theories of judgment and keep mostly to the issue of double judgments.

Franz Brentano’s 1874 Psychology from an Empirical Standpoint presents us with a framework and methodology for performing scientific research in psychology. Moreover, this project provides the foundation for the more ambitious ideal of the renewal of philosophy as a science, which had been Brentano’s aim ever since defending his habilitation thesis that “the true method of philosophy is none other than that of the natural sciences”. Brentano therefore needs to carefully articulate the precise position and role of his scientific psychology among the Geisteswissenschaften and the Naturwissenschaften. What does his ideal of philosophy as science consist in? What is the relation between his scientific psychology and philosophy? How is psychology related to the natural sciences, in particular psycho-physics and physiology?

In the second edition of the Logische Untersuchungen Husserl claims to have investigated higher order objects and Gestalt qualities before anyone else in the School of Brentano. Indeed, in the Philosophie der Arithmetik we find a discussion of figural moments and fusion that could lend some support to such a claim. By considering the concepts of Gestalt and Verschmelzung in their relevant historical context, the latter especially in connection to Stumpf, we find that Husserl indeed gave a quite original and interesting account of such higher order phenomena.

Franz Brentano is not usually associated with mathematics. Generally, only Brentano’s discussion of the continuum and his critique of the mathematical accounts of it is treated in the literature. It is this detailed critique which suggests that Brentano had more than a superficial familiarity with mathematics. Indeed, considering the authors and works quoted in his lectures, Brentano appears well-informed and quite interested in the mathematical research of his time. I specifically address his lectures here as there is much less to be found about mathematics in his published works. Besides Brentano’s own work, it is quite remarkable to see that practically all of his better-known students sooner or later produced a work on the philosophy of mathematics. This also encourages the supposition not just of a common interest in the matter, but of a common theoretical core. All this prompts the question: Can we speak of a Brentanist philosophy of mathematics?

Both Alexius Meinong and Edmund Husserl wrote about relations in their early works, in periods in which they were still influenced by Franz Brentano. However, besides the split between Brentano and Meinong, the latter also accused Husserl of plagiarism with respect to the theory of relations. Examining Meinong’s and Husserl’s early works and the Brentanist framework they were written in, we will try to assess their similarities and differences. As they shared other sources besides Brentano, we will consider very carefully whether we should speak at all of influence or plagiarism. Despite Meinong’s accusations it seems that both he and Husserl took over some elements from Brentano and, partially through him, from John Stuart Mill, who appears to be the most probable source on relations.

In this article we will address the issue whether and in how far Anton Marty had a significant influence on the development of the phenomenological movement. As “the phenomenological movement” is not a clearly defined and circumscribed notion, we need to provide an appropriate context for any comparison. The phenomenological movement grew out of the School of Brentano and we take this larger whole as our starting point. Since Marty did not found his own school or movement, but remained a Brentanist, it is quite difficult to identify a clear influence of Marty on the phenomenological movement that would not be intermingled with a general Brentanist background. A specifically Martian influence could perhaps mainly be found in the philosophy of language. We will look at Marty’s and Husserl’s shared background, mutual criticisms and common legacy in order to evaluate the significance of any influence there might have been.

Edmund Husserl’s engagement with Bertrand Russell’s paradox stands in a continuum of reciprocal reception and discussions about impossible objects in the School of Brentano. Against this broader context, we will focus on Husserl’s discussion of Russell’s paradox in his manuscript A I 35α from 1912. This highly interesting and revealing manuscript has unfortunately remained unpublished, which probably explains the scant attention it has received. I will examine Husserl’s approach in A I 35α by relating it to earlier discussions of relevant topics in his manuscripts and the broader historical context of the School of Brentano and early phenomenology.