Abstract, Norman Sieroka (ETH), 1/2 An Exemplary Case for an Integrated Historiography of Philosophy and Science: Weyl, Medicus, and the Concepts of Surrounding The aim of this paper is to sketch an approach for integrating the historiography of science and of philosophy in a systematic way. Although the details of this approach are tailor-made for a certain historical period and specific context, it might be viewed as an exemplary case for integrated approaches on science and philosophy also in other historical contexts. The present approach makes central use of the concept of surrounding and has been elaborated for a systematical and historically detailed assessment of the interaction between the eminent mathematician Hermann Weyl and the philosopher and Fichte scholar Fritz Medicus in Zurich around 1920. As their published and unpublished work, correspondences, and further archived material shows, they both stood in close intellectual contact and scientific exchange: they quote each other in their publications, took extensive notes and commented on each others drafts and publications, attended each others lectures, met regularly to read the main works of Fichte, etc. In his writings on the philosophy of mathematics and physics Weyl often develops rather intriguing positions. It is especially the work of Fichte and Husserl which influenced and shaped his position. From a present day perspective these philosophers seem to be rather strange allies for a mathematician and philosopher of science. However, if considering the historical documents on Weyl's “constructive intellectual interference” with Medicus (and his undergraduate days in Göttingen, where he attended lectures by Husserl) these references appear rather straightforward and also make plausible the otherwise rather unconventional details of Weyl's Fichte reception. In turn, something similar is true of Medicus's philosophical work. Hence, I suggest that the close historical study of this academic constellation (surrounding, environment) between Weyl and Medicus allows for a systematic reconstruction of their positions. The particular historiographical method I suggest for investigating such a historically concrete intersubjective environment is (a slightly revised version of) Konstellationsforschung. This method has recently been introduced by Henrich, Mulsow and others and focuses on the close investigation of historical documents in order to reconstruct the “space of thought” (Denkraum) of a constellation (surrounding) of people. Besides, this method was originally developed to comprehend the beginnings of German idealism in Jena around 1800; i.e. in a context which, like the present one, involved many considerations and assumptions related to the philosophy of Fichte. Moreover, the concept of surroundings also played a crucial role in the various topics discussed by Weyl and Medicus and arguably led them to structurally analogous approaches in the philosophy of mathematics and physics and in the theory of subjectivity. Let me briefly hint at some of the issues involved here: In his philosophical writings of around 1920 Weyl aimed to show that the then prominent debate between intuitionism and formalism can be understood as a debate about whether truth is related to some sort of disclosure or creation; a debate which, at least for Weyl, was related to an innerphilosophical dispute between Husserl’s phenomenology and Fichte’s “doctrine of knowledge” (Wissenschaftslehre). In the same context, the treatment of the topological analysis of the continuum led Weyl to a discussion of the concept of surroundings. (In English the technical mathematical term here is “neighbourhood”. However, here as well as in the following cases the German term for surrounding/neighbourhood/environment is always “Umgebung”.) Abstract, Norman Sieroka (ETH), 2/2 Around the same time and in reaction to certain inconsistencies and tensions between field physics and atomic (later quantum) physics, Weyl developed an agency theory of matter. Here his considerations on continuity and discreteness transferred from the mathematical to the natural realm. Weyl now understood matter to be something which causes effects in space-time without being a part of space-time itself. The alleged “inside of matter” is, for him, not an object for science—the only things which exist in this realm are the spatiotemporal neighbourhoods (“surroundings”). And, like in the case of mathematical neighbourhoods, Weyl referred to Fichte to motivate his view. Next, in Medicus' writings on the theory of subjectivity the tension between continuity and discreteness (re-)appears as a tension between a community and an individual. According to Medicus the concept of a human individual is a limiting idea, constituted by means of overlapping communities (in the sense of personal environments or surroundings). His approach is strongly influenced by Fichte's early accounts on (inter-)subjectivity and developed during the time of his close intellectual interaction with Weyl. Accordingly, it is hardly a coincidence that Medicus's concept of a person is structurally analogous to Weyl's concept of a point in mathematics as being constituted by means of neighborhoods and as being a limiting idea. Moreover, Medicus's concept of (inter-)subjectivity and personal surroundings links back directly to the methodology of Konstellationsforschung. To sum up: Weyl's and Medicus's approaches within these very different philosophical and scientific areas show striking similarities. They all refer to certain concepts of (mathematical, spatiotemporal, intersubjective) surroundings to enable a satisfying treatment of a certain tension between continuity and discreteness. Points, matter, humans are all constituted by their surroundings. Furthermore, the concept of personal surroundings also forms a constitutive part of the historiographical assessment of the philosophical positions and debates involved. Thus, by focusing on the personal environment of Weyl and Medicus a particular unity of content and method is reached; an integration of historical and systematic thinking which is congenial to what Medicus and Weyl themselves demanded in their philosophical writings. Arguably, this specific kind of nearness between the historical material and the way in which it is approached is also crucial for making the issues and debates encountered in the historical surrounding contractible and relevant for our current expressions of similar concerns and debates. My claim is not that the look at surroundings is the universal remedy for the historiography of science and of philosophy. Other protagonists, times, disciplines, and debates might likely suggest focusing on other concepts and methods. However, what I suggest is that there might be combinations between content and method which produce a certain nearness to the historical material and which might make us see former philosophical problems as being variations of our current ones.