Normal type
Normal type (in German: Normaltyp) is a typological term in sociology coined by the German sociologist Ferdinand Tönnies (1855–1936). It can be considered both as a forerunner of, and a challenge to, the rather better known concept of Max Weber’s: the ideal type (in German Idealtyp).
Tönnies’ distinctions
Tönnies drew a sharp line between the realm of conceptualization (of sociological terms, including ‘normal types’) and the realm of reality (of social action). The first must be treated axiomatically and in a deductive way (pure sociology); the second, empirically and in an inductive way (applied sociology). Following Tönnies, reality (the second realm) cannot be explained without concepts, which belong to the first realm, or else you will fail because you try to define x by something derived from x.
Tönnies’ Normaltyp was thus a conceptual tool created on a logical basis, an almost mathematical concept always open to subsequent refinement from a confrontation with the empirical evidence.