 Many philosophical traditions investigate how individuals mentally construct, organize, categorize, or represent social objects—and objects more generally. Some views regard social categories to be concepts that individual minds assemble in order to organize subjective impressions. An example is a Lockean “nominal essence” theory of social categories (see  section A.2.4 of the supplement).  In this theory, a given person’s social category cha-cha is an idea in that person’s mind, formed out of combinations of impressions or other ideas internal to that person’s mind.