Leon Chwistek, a Polish mathematical logician, philosopher, aesthetician, essayist, and painter, was a lecturer at the University of Kraków and from 1930 a professor of mathematical logic at the University of Lvov.

Theory of Realities

The central problem of Chwistek's philosophy was a criticism of the idea of a uniform reality. It had been shown by Bertrand Russell that in logic admission of the totality of all functions of x produces contradictions; Chwistek claimed that in philosophy, likewise, many obscure and misleading thoughts result from the assumption of a single all-inclusive reality.

The results of this criticism led Chwistek to the thesis of a plurality of realities. Out of many possible realities four are particularly important to philosophy. The first, the reality of natural objects, is assumed by common sense; natural objects are of a given form regardless of our perception. Chwistek's defense of...