Abstract

Werner Heisenberg made an important – and as yet insufficiently researched – contribution to the transformation of the modern conception of science. This transformation involved a reassessment of the status of scientific knowledge from certain to merely hypothetical – an assessment that is widely recognized today. I examine Heisenberg’s contribution in particular by taking his conception of “closed theories” as an example according to which the established physical theories have no universal and exclusive, but only a restricted validity. Firstly, I characterize the historical process of hypothetization of claims to validity. Then, secondly, I reconstruct Heisenberg’s conception, as far as it can be derived from his popular writings, relating it to the process of hypothetization. Finally, I touch on the history of its reception and compare it with conceptions of science that emphasize the significance of the hypothetical for the modern theories of natural sciences. Compared to these conceptions, Heisenberg’s contribution turns out to be rather independent.