Originally published as REALITY IN HEISENBERG'S PHILOSOPHY, Chapter Eight of Patrick A. Heelan, Quantum Mechanics and Objectivity (The Hague: Nijhoff, 1965), pp. 137-155.


Continental Philosophy | History of Philosophy | Logic and foundations of mathematics | Philosophy of Science


This chapter contains a study of Heisenberg's views of the ontological content of quantum mechanics from I925 until the present day. During the quantum revolution of I925, he began by accepting a Berkeley-type empiricism in which the reality of a quantum mechanical system was reduced to that of a set of observation events, which were, however, acausally connected and in consequence did not constitute a stable phenomenal object of experimental knowledge. After 1955, he professed a modified form of Kantian philosophy whose starting point was the existence of universal and necessary scientific laws. Those universal and necessary scientific laws from which Kant started have been shown to belong only to restricted domains of intuitive experience (the domain of everyday life and classical physics). Heisenberg defines noumenal reality as the object of an intellectual intuition (episteme) which, however, is a kind of knowledge we do not possess. We know noumenal reality only through symbols in an intellectually patterned experience. There are two kinds of noumenal reality: there is the thing-in-itself which is the correlate of the phenomenal object, and there is the dunamis (or Aristotelian potentia or objective tendency) which is the correlate of the quantum mechanical system (e.g., elementary particle, atom, etc.). The latter is the noumenal correlate of the phenomenal or experienced union of subject and object taking place in the act of observation. The importance of universal symmetries in the expression of general laws of nature is stressed by Heisenberg, and these constitute for him the true basis for transcendental philosophy.