0197 Prisoner's Dilemma
Q197. Explain and give an example of a dominant strategy in a prisoner's dilemma game.
- This question derives from the ideas presented by Robert Axelrod in articles on the evolution of cooperation and cooperation during combat in World War I.
- Axelrod is a contemporary political scientist.
- Prisoner's Dilemma is an example of a "game" studied in the field of game theory. Game theory is most often associated with economics though other fields make use of it too (including sociology, political science, computer science, robotics, and international relations).
- In a prisoner's dilemma game there are two player or "prisoners." We imagine they have been arrested on suspicion of having done a crime together.
- The police separate the two players and attempt to get them to "rat on" one another. The police suggest that if one rats on the other the rat will get off with a lighter sentence.
- There are three different outcomes: both prisoner's remain silent, one rats while the other stays silent, or both betray their partner.
- To be a prisoner's dilemma game, the "rewards" associated with the different outcome have to stand in a certain relation to one another. Namely:
- Ratting on a partner who stays silent (temptation) is better than both maintaining silence (mutual cooperation)
- Both maintaining silence (mutual cooperation) is better than both caving in (mutual defection)
- Both caving in (mutual defection) is better than being ratted on while you stay silent (sucker's payoff)
- For each individual, defection (ratting) is better than cooperation (silence) no matter what the other player does.
- If A is silent, B is better of ratting (temptation > mutual cooperation)
- If A talks, B is better off talking (mutual defection > sucker's payoff)
- We say that a strategy (a choice of "moves") is DOMINANT if it is the better strategy against any possible move by the opponent.
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