Concept drifting detection is one of hot topics in data stream mining, and analysis of uncertainty is dominant in rough set theory. Combined with the ideas of data stream, concept drifting, rough sets and F-rough sets, a lot of concepts such as concept drifting of upper approximation, concept drifting of lower approximation, concept coupling of upper approximation and concept coupling of lower approximation etc are defined. The change of concepts in an information system is analyzed with these definitions. With the positive region, integral concept drifting, integral concept coupling are defined. The analysis and measurement for the change of concept uncertainty are conducted. From the view of epistemology, the concept of cognition convergence is defined from the ways of idealism and realism. It provides heuristic information for realizing the world of human beings from the viewpoints of granular computing and rough sets.