This paper argues that concepts have a dual character in terms of their members since the latter have a set of concrete features and abstract values. It is investigated whether a single object is a category member or not. In order to explore this hypothesis seven concepts are experimentally tested: SCIENTIST, ART, CRIMINAL, TEACHER, ROCK MUSIC, MOTHER AND LOVE. Moreover, it is argued that category membership is subject to normative evaluations according to which typicality judgments are affected by the degree to which an object falls into certain taxonomies. Specifically, the human conceptual system supports two types of normative evaluations: i) object concreteness and ii) the degree to which object’s concreteness embodies abstract values. Finally, the experimental part of the study has shown that there are two degrees for category membership: a) humans check whether a given object actually has concrete features and b) they identify the abstract values of these concrete features and then they check whether the object displays these abstract values.