To make use of a philosophical concept in practical thinking is one thing, to render a pure and meaningful formulation of the concept quite another. Everyone faces the necessity of judging the truth of various assertions, and in daily life, as in science, methods have been developed in accordance with which we more or less consciously make such judgments. But the meaning of truth is not given along with the use of the concepts; it can only be grasped by philosophical reflection upon the sense and meaning of the processes of knowledge. To give you a glimpse into such epistemological research is my purpose today.