Streszczenie
The article outlines the development and main principles of Kazimierz Twardowski’s epistemology which had the greatest relevance for the Polish contemporary theory of knowledge. The primary emphasis was placed firstly upon abandoning psychologism, which characterized his early philosophy, secondly upon the main principles of Twardowski’s late philosophy. In the last period, the Polish philosopher developed the autonomous, i.e. independent of psychology, concept of epistemology as the field of philosophy concerning the issue of truth and, in particular, the veracity of judgments.