Abstract

Stöltzner coined the expression ‘Vienna indeterminism’ to describe a philosophical tradition centered on the Viennese physicist Exner, serving as the ‘historical link’ between Mach and Boltzmann, on the one hand, and von Mises and Frank, on the other. During the early 1930s debate on quantum mechanics, there was a ‘rapprochement’ between Vienna indeterminism and Schlick’s work on causality. However, it was Cassirer’s 1936 monograph _Determinismus und Indeterminismus_ that showed a full ‘convergence’ with major tenets of Vienna indeterminism: the fundamentality of statistical laws, the frequency interpretation of probability, and the statistical interpretation of the uncertainty relations. Yet, Cassirer used these conceptual tools to pursue ‘in parallel’ different philosophical goals. While for the Viennese quantum mechanics represented a fatal blow to the already discredited notion of ‘causality,’ for Cassirer it challenged the classical notion of ‘substantiality,’ the ideas of ‘particles’ as individual substances endowed with properties. The paper concludes that this ‘parallel convergence’ is the most striking and overlooked aspect of _Determinismus und Indeterminismus_, serving as the keystone of its argumentative structure.