Abstract
This paper focuses on the theory of plurality of realities introduced by Leon Chwistek. A critical analysis of this theory and an extensional interpretation of Chwistek’s axiomatic descriptions of four realities lead to an epistemological interpretation of this theory. The word “plurality” in the title is a result of different waysof understanding the same original set of sense-data. This interpretation is contrasted with Kazimierz Pasenkiewicz’s ontological version of this theory. In the final parts of the paper the most important consequences of this theory are discussed. First, the ethical relativism postulated by Chwistek is criticized. Second, an attempt to illustrate the plurality of realities with an example of different styles of painting is discussed. Third, a critical rationalism in the form of a kind of practical attitude toward social reality, which results from the theory of plurality of realities, is outlined.