Understanding and communication cannot be conceived without referring to common sense. But, from another side, the coming out of significant new knowledge needs overrunning this common sense, which implies breaking out with it. Can these two exigencies, which appear at first sight contradictory, be conciliated? One must consider that when truly new knowledges are assimilated and have become fully intelligible, so as to be taught, and even popularized, and to serve as a basis to go further towards other, newer, knowledges, the first ones are henceforth part of a new "common sense", modified and different from the preceding one, but still having the same function for understanding and communication. We show, by taking various examples from contemporary physics (relativity theory and quantum physics), that this renewed common sense takes profit of the widenings of rationality which allow to conceive that a progress of knowledge is possible. These considerations entail ethical implications, from the point of view of communication, concerning the sharing of knowledge with non-specialists in intelligible terms, through a common sense submitted to the requirement of criticism. Consequently, it appears necessary to think about the elements of meaning of knowledge whose sharing has priority, and about the conditions of such a sharing.
Common sense; Popularization; Understanding; Comunication; Rationality; Intelligibility; Ethics; Quantum physics; Relativity theory