The subject of the paper is an analysis of a programme of sociology of scientific knowledge, initiated by Florian Znaniecki in his book 'The Social Role of the Man of Knowledge' (1940) and his other works in science of science. Author points out to a series of significant affinities between Znaniecki's sociological theses and the claims of the philosophy of science put forward by Karl Popper. He argues that, despite the fact that Popper, an epistemologist, stressed that 'the course of human history is to a large extent dependent upon the growth of human knowledge', while Znaniecki's approach may be summarised by saying that 'the growth of human knowledge is to a large extent dependent upon the course of human history', both of these perspectives complement each other and provide a fuller understanding of human knowledge. Through a comparison of Znaniecki's view of science with Jacob Bronowski's conception of scientific knowledge, the author also points out some inconsistencies in Znaniecki's understanding of science, arguing that his sociology of knowledge did not free itself from a philosophical dimension, as Znaniecki thought it had done, and remains only a provisional construction. For, despite his efforts, his conception has stumbled upon significant limitations of the sociological method in explanation of the growth of knowledge, which Znaniecki attempted to overcome by encroaching upon the areas of epistemology, logics, and psychology of knowledge.