This essay attempts to provide a preliminary outline of a theory of identity. The first section addresses what the sociologist Niklas Luhmann has called ‘the problem of identity’, or, in other words, the mind–society (rather than the mind–body) problem: In how far can the internal (psychological) self and the external (social) persona be integrated into a unit? The second section of the essay briefly defines a basic vocabulary of a theory of identity. ‘Identity’ is understood as the existentially necessary formation of a coherence between the ‘self’ (the ‘I’ as it is experienced in thoughts and feelings), its body and its social ‘persona’ (the individual person with its social attributes). Three different major paradigms of identity formation are distinguished from one another: a sincere identity is constructed through a firm commitment of the self to its social roles; an authentic identity is constructed through the creation of a social persona on the basis of one’s unique and original self; a ‘profilic’ identity, as we call it, is shaped by successfully presenting a personal profile under conditions of second-order observation as they prevail, for instance, in the social media, but also in other contemporary social systems. In the third section of the essay, we present a sketch of the historical sequence of these three paradigms of identity. Although these paradigms are not mutually exclusive and can coexist, it seems that sincerity flourished in pre-modern society, while authenticity came to prominence along with the functional differentiation of modern society and is now, along with the increased significance of second-order observation, gradually overshadowed by the influence of profilicity.