In this introductory chapter, we provide a roadmap to the discipline “history of philosophy of science” (HOPOS) first by briefly considering its starting point and mission, and then by examining, separately, each of its components and the various perspectives associated with them. We conclude the second section by showing how the synergy obtained by merging these various components can offer effective resources that are valuable beyond this field. In the subsequent sections, we present an overview of the volume, its scope, and, finally, the rationale behind our editorial choices.

The correspondence presented in this Appedix, which comprises four letters that Hans Reichenbach and Gustav Wyneken exchanged in the spring of 1915, originated following Wyneken’s controversial public lecture Der Krieg und die Jugend, which he delivered to the Munich Free Students (Freie Studentenschaft) on 25 November 1914. In the lecture, Wyneken defended a contentious position in support of war that many interpreted as contradicting views expressed in previous writings. Wyneken’s position was based on the idea that a war, however cruel, still represented an opportunity for a positive societal transformation through the “emancipation” of youth that would necessarily result from it; this was an idea that several Freistudenten, who admired his earlier notion that the essence of youth was meaningful in and of itself, would never subscribe to. The extensive debate that arose from his provocative stance involved several Free Students. How meaningful it must have been for so many of them is clearly exemplified by the Reichenbach-Wyneken exchange, which captures the contrast between the reality of war as embraced by Wyneken and Reichenbach’s own “ethical ideal”.

Like many of his contemporary students, Hans Reichenbach was a member of the Freistudentenschaft. This movement strongly defended the idea of moral self-determination and intellectual autonomy of the individual, and aimed at reforming the German university system that the Free Students regarded as no longer adequate to reflect their needs. As a Free Student, Reichenbach stood against any form of dogmatism, be it scholastic, religious, philosophical, political, or institutional. It is against this background that he developed the ideals that would ultimately provide the basis for his philosophical thought, and to which he would remain faithful until the end of his life.

The aim of this paper is to provide a brief overview of Reichenbach’s experience as a Free Student and its impact on his later work. I will consider archival materials that significantly epitomise his early involvement within the German Youth Movement, specifically in relation to: his political partaking in the university reform, which extends until 1919; a psychological research project he carried out around 1912–1913; and his position on the war, which emerges in his 1915 correspondence with the education reformer Gustav Wyneken.

Few philosophical problems occupied Reichenbach as much as the problem of the justification of induction. How can we avoid the potential circularity of attempts that end up involving inductive reasoning—the difficulty that lay at the core of Hume’s skeptical reasoning? From his doctoral dissertation to the publication of his Theory of Probability twenty years later, Reichenbach aimed to provide mathematical and methodological foundations for his interpretation of probability and thereby furnish a solution to Hume’s problem of induction. It is argued that this proposal is unavailing, but that the discussions it triggered have inspired a rich amount of literature until the present day. This chapter analyzes how Reichenbach’s theory of probability and his conception of induction was received and looks closely at the criticism it received by Popper.

In the philosophy of science, Reichenbach’s position is often regarded as aligned with some form of conventionalism, especially in connection with space-time theories. The notion of conventionalism is referred to in various ways, indicating different aspects of a more general problem, the relation between theory and reality. One version of the conventionalist thesis can be expressed through the thesis of underdetermination of theory by evidence. On the other hand, the notion of conventionalism comes into play when explaining how we can apply abstract conceptual systems to reality. While Reichenbach’s writings lend themselves to both these readings, in this chapter, I will mainly be discussing the second one, especially focusing on his early writings as well as on his approach to the way we define some fundamental terms of a theory in relation to the application of theory to experience, which is where the notion of “coordination” plays an essential role.

Reichenbach’s doctoral thesis aimed at an account of the principles of probability and causality in Kantian terms. Yet, the position he assigned to probability appeared from the outset to be at odds with a Kantian deterministic framework. His defence of the frequency (objective) interpretation of probability, moreover, made him oppose the other quite popular view on probability, the logical (epistemic) interpretation of von Kries. Soon after, despite his early criticism of the neo-Kantians’ analysis of general relativity, Schlick published a paper on the meaning of the causal principle that seemed to Reichenbach like a return to Kant. Schlick’s interpretation was moreover inspired by Kries’s Spielraumtheorie. In their works on these topics, both Schlick and Reichenbach provided a different reading of Planck’s 1914 famous distinction between statistical and dynamical lawfulness. This paper intends to reconstruct their different positions until their 1931 public disagreement in the pages of Die Naturwissenschaften, following its origin in the different way they reacted to some of Kries’s insights, on the one hand, and according to the different emphasis they put on Planck’s distinction, on the other.

One of the most interesting aspects of Heil (2003) consists in the rejection of the traditional opposition between dispositional and categorical properties, parallel to a no-level view of reality. I argue that, from an epistemological perspective, this demands a definite stance on the real meaning and role that laws of nature play in this account. Unfortunately, this issue is not treated by the author in due detail. I will show that an adherence to a “mixed” categorical-dispositional interpretation of properties is incapable of adequately reflecting the business of science, unless some additional explanation is provided of how scientific law statements tell us something about the real world.