Current epistemological problems and the use of a three-valued logic in quantum mechanics

pp. 226-236

in: Hans Reichenbach, Selected writings 1909–1953, Berlin, Springer, 1978

Abstract

Today, physics plays a more important role in philosophical discussion than ever before, for physical research has led to a revision of certain very general principles of our knowledge of nature. The philosophical results first became apparent in Einstein's theory of relativity, which taught us to regard the spatial and temporal dimensions of the physical world in a new light. It turned out that the excessively simple concepts of space and time that have been developed in connection with our physical surroundings in everyday life can no longer be reconciled with the results of precise optical and electromagnetic measurements. Yet the transformation of basic concepts that was consequently demanded of us now appears trivial compared to the changes in our vision of the physical world brought by quantum mechanics. For the physics of quanta demands that we give up the idea of universal causality — the idea that was regarded, all the way up through the theory of relativity, as the most fundamental principle of classical physics, without which natural science appeared to be impossible.