Tit for tat is only one possible self-confirming equilibrium among many

Evidence

Thus tit for tat can be an equilibrium only if both players believe the other will abide by it, otherwise other equilibria are just as possible and selfconfirming. To show that trust is really not at stake, Axelrod should have shown that whatever the initial move and the succession of further moves, the game tends to converge on tit for tat. — Diego Gambetta, Trust - Making and Breaking Cooperative…, 2814

Categorization

• XREF: Undercuts the naive Hart-folk theorem optimism: equilibria are multiple and belief-dependent, so observability alone doesn’t pin down cooperation — it needs shared beliefs, connecting to Luhmann’s familiarity as belief infrastructure.