Heisenberg and the Problem of Causality

The discovery of quantum physics opened a broad debate on the epistemological status of the principle of causality. In this article, I analyze the problem of causality in Heisenberg by distinguishing two levels of philosophical explanation in his thought. As a philosopher of science, his understanding of causality is closely linked to Moritz Schlick, although he will later adopt a neo-Kantian view of the a priori. As a philosopher of nature, Heisenberg recovers the notion of potency to understand the wave function. My thesis is that this notion of potency could have allowed him to elaborate a realistic and nondeterministic theory of causality, but the identification of causality and determinism (in Schlick’s line) did not lead him to such a conclusion.