Tit for Tat

02What People Think

“Tit for tat means hitting back harder whenever somebody disappoints you.”

03What’s Underneath

In repeated-game research, tit for tat follows a narrow rule. A player cooperates in the first round. In every later round, that player chooses the action the other player took in the immediately preceding round. If the other cooperated, cooperate; if the other defected, defect.

Imagine a repeated choice about whether to help a neighbor. A person using this rule begins by helping, then bases the next decision on what the neighbor did last time. The rule responds to an uncooperative move but also resumes cooperation after a cooperative one. It does not permanently tally every offense or escalate the response.

Tit for tat became well known through Robert Axelrod’s computer tournaments, but it is not a universal best strategy. Outcomes depend on the game, other strategies and how accurately actions are observed. Mistakes and misunderstandings can provoke repeated retaliation. Everyday reciprocity is a broader idea and does not require this exact first move or one-round memory.

04The Game

Is the response copying the previous action, escalating it or remembering a much longer history? Those differences separate a precise repeated-game strategy from the everyday phrase “getting even.”