Tit for tat

For other uses, see Tit for Tat (disambiguation).
In Western business cultures, a handshake when meeting someone is a signal of initial cooperation.

Tit for tat is an English saying meaning "equivalent retaliation". It is an alteration of tip for tap "blow for blow",[1] first recorded in 1558.[2]

It is also a highly effective strategy in game theory. An agent using this strategy will first cooperate, then subsequently replicate an opponent's previous action. If the opponent previously was cooperative, the agent is cooperative. If not, the agent is not. This is similar to reciprocal altruism in biology.

  1. ^ "tit for tat". Etymology Online. Archived from the original on 2023-07-26.
  2. ^ Heap, Shaun Hargreaves; Varoufakis, Yanis (2004). Game theory: a critical text. Routledge. p. 191. ISBN 978-0-415-25094-8.