The social scientist is able to grasp them because the everyday world is intersubjective, or “socialized”, and he or she can employ variations on the same devices that ordinary members of society use to understand each other, of which typifications are the most obvious. Given the two-way traffic between lay and social scientific concepts and the part played by both in the constitution of society, conceptual relativism of a kind is inescapable. Parsons failed in his self-appointed mission to establish an exclusive categorical system for all social science. Gallie gave as examples of essentially contested concepts, religion, art, science, democracy, and social justice. Schutz argued that social scientists must respect the postulate of adequacy but are otherwise free to introduce factors relevant only to science in their constructs. Social reality, by contrast, frequently minds very much; both primary and secondary conventions are involved; and the teaching and learning of similarity relations often acquires a contested, even political, character.