  The fourth group has to do with causes; they include questions about how categories are established or brought about. These issues have attracted considerable attention in recent years, particularly among post-modern philosophers, such as Michel Foucault (1926–84). In the Middle Ages the way this question is posed depends heavily on the ontological status accorded to categories, particularly on whether they are mental or extra-mental entities. The Foucauldian concern with “social construction,” however, seems to be absent from medieval discussions.