In traditional cultures, with the partial exception of some larger city neighbourhoods in agrarian states, there was a quite clear divide between insiders and outsiders or strangers. The wide arenas of nonhostile interaction with anonymous others characteristic of modern social activity did not exist. … The opposite of “friend” is no longer “enemy,” nor even “stranger”; rather, it is “acquaintance,” “colleague,” or “someone I don’t know.” In accompaniment with this transition, honour is replaced by loyalty which has no other support save personal affection, and sincerity is replaced by what we can call authenticity: the requirement that the other be open and well-meaning.

QUESTION: What exactly distinguishes authenticity (openness and good intentions toward strangers) from sincerity? Worth understanding the genealogy of this shift.

Anthony Giddens, The Consequences of Moderni…, loc. 280