Tit For Tat
Farnam Street (Shane Parrish), after Anatol Rapoport · 2022
"In repeated (iterated) games, the most effective strategy is tit for tat: cooperate first, then simply mirror whatever your counterpart did last time — ideally with occasional forgiveness built in to escape cycles of mutual retaliation."
Under tit for tat, a player starts by cooperating, then in every later round simply repeats whatever their counterpart did in the previous round — reciprocating cooperation with cooperation and defection with defection. In a single, one-shot interaction (not repeated), game theory suggests defection is actually the better strategy, since there's no future round in which reciprocity could be rewarded or punished.
'Tit for tat with forgiveness' — occasionally cooperating even after the other side defected — improves on strict tit for tat because two strict tit-for-tat players can otherwise get permanently locked into a cycle of mutual retaliation with no way out; a single forgiving cooperative move can break that cycle and restart mutual cooperation, which matters because most real-world relationships (unlike a single prisoner's dilemma round) are iterative and compounding over a long horizon.
Who is credited with codifying 'tit for tat' as a formal game-theory strategy?
Read more about the topic
The explanation above is written with AI assistance. These are the originals — go to them to check it.
- Reciprocity (the related mental model)Farnam Street
- A Multidisciplinary Approach to Thinking (Peter Kaufman)Farnam Street
Prisoner's Dilemma: What Game Are You Playing?
"The Prisoner's Dilemma shows that individually rational self-interest can produce a jointly worse outcome for everyone — but when the same game repeats indefinitely with an unknown end point, cooperation becomes far more likely to emerge and persist."