Prisoner's dilemma

The prisoner's dilemma is a type of non-zero-sum game (game in the sense of Game Theory). In this game, as in many others, it is assumed that each individual player ("prisoner") is trying to maximise his own advantage, without concern for the well-being of the other players.

Related Topics:
Non-zero-sum - Game Theory

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The Nash equilibrium for this type of game does not lead to Pareto optimums (jointly optimum solutions). In equilibrium, each prisoner chooses to defect even though the joint payoff would be higher by cooperating. Unfortunately for the prisoners, each has an individual incentive to cheat even after promising to cooperate. This is the heart of the dilemma.

Related Topics:
Nash equilibrium - Pareto optimum

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In the iterated prisoner's dilemma the game is played repeatedly. Thus each player has an opportunity to "punish" the other player for previous non-cooperative play. Cooperation may then arise as an equilibrium outcome. The incentive to cheat may then be overcome by the threat of punishment, leading to the possibility of a superior, cooperative outcome.

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