Abstract
The present discussion arose from the desire to explain, to an audience of non-physicists, the epistemology to which one is forced if one pursues the quantum mechanical theory of observation to its ultimate consequences. However, the conclusions will not be derived from the aforementioned theory but obtained on the basis of a rather general analysis of what we mean by real. Quantum theory will form the background but not the basis for the analysis. The concept of the real to be arrived at shows considerable similarity to that of the idealist. As the title indicates, it is formulated as a dualism. It is quite possible that it will soon be rejected not only by the community of the philosophers but also by that of the scientists. If this should be the case, the attempt to derive an epistemology from physics will prove to have been premature. Naturally, the author hopes that this will not be the case because, quite apart from the quantum theoretical background, the concepts to be presented appear natural also as an outgrowth of common sense considerations. They have been arrived at by many who did not accept the epistemology of quantum mechanics.