 As for Feigl’s own development, his doctoral dissertation under Schlick’s supervision should be mentioned first. Submitted in July1927, the purpose of this study was to examine the problem of the application of the probability calculus, hence its title “Chance and law: an epistemological analysis of the roles of probability and induction in the natural sciences.” Heavily inspired by Edgar Zilsel’s Das Anwendungsproblem (1916), Feigl argued along pragmatic (Humean) lines. His central thesis was that the problem of induction cannot be solved by making recourse to the probability concept. Feigl, thereby criticizing especially the point of view defended by Hans Reichenbach, proposed instead a ‘vindication’ rather than a ‘validation’ of inductive reasoning. Relying on a frequency interpretation of probability, he argued that the limiting value of an infinite sequence can only be inferred inductively, which in turn implied that probability is dependent on induction and not vice versa. Concerning the principle of induction itself, Feigl (like his teacher Schlick) saw no other possibility than to interpret it as a pragmatic (or operational) maxim. On the whole, however, the approach laid down in Feigl’s dissertation was, as Feigl himself later conceded (see Feigl 1981, p. 6), severely limited by its neglect of the simultaneous rise and development of quantum mechanics.