If "naturalistic epistemology' is broadly construed to mean the investigation of human cognition as a natural phenomenon, then Piaget's work should be recognized as the most massive contribution to the discipline made by any single person. One wishes to know, however, what the relevance of Piaget's work is to a more narrowly construed naturalistic epistemology — to a normative discipline which is devoted to judging epistemic claims, but which does so partly by means of scientific information about man's place in nature. Some of Čapek's remarks help to answer this question, even though he has not undertaken to do so systematically.