In the Prisoner’s Dilemma, two players face a choice between cooperating (C) or defecting (D). Mutually cooperating results in a modest reward, while both defecting leads to a lower payoff. However, a defector always gains more than a cooperator, regardless of the other player’s choice. The grim trigger strategy, introduced by Robert Axelrod, involves cooperating initially but defecting thereafter if the opponent ever defects. This strategy promotes cooperation by punishing defection, balancing the rewards of cooperation and defection, and encouraging long-term cooperation.
