Abstract: In this paper, we present a study that can be seen as a partial bridge between didactic researches centered around epistemological concerns like epistemological obstacles and sociological approaches that can be used in educational sciences. To do so we use an anthropological approach to the didactic of mathematics, the anthropological theory of the didactic (ATD) and in particular its “scale of levels of didactic codetermination”. This enables us to bring into the fore a set of constraints emanating from institutions located at a high level of this scale. The two institutions we are considering are the modern mathematics reform and the counter-reform that followed. The constraints generated by these institutions form a dense network that compels the possible shapes mathematical knowledge can take on. Such stringency leads to some hybridization of the deductive and argumentative architecture of courses subdued to these constraints. The concepts become two sided. They bear at the same time a mathematical side, the most visible one, which has a mathematical legitimacy and another less visible one whose role is to allow these concepts’ ecological viability. The implicit and unconscious shifts between these two polarities tend to reinforce cultural mimetic encounters of knowledge based on ostensive practices.