Sublime

how cooperation can emerge among egoists without central authority.

All TFT did was cooperate on the first Prisoner’s Dilemma round, then in every subsequent round, it did whatever the opponent did previously—that is, if on the previous round the opponent cooperated, it cooperated on the next round; if the opponent betrayed, it betrayed on the next round. This simple program decimated the competition. So Axelrod ra

Tit for tat is a strategy which, according to game theory, is the most effective choice for iterated games based on mutual cooperation or defection. Both players benefit if they cooperate, but one benefits and the other loses out if only they defect, and both lose out to a lesser extent if they simultaneously defect. As abstract as such games sound

The take-home message from Schelling’s story—that incentives sometimes backfire—is familiar to psychologists.