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TitForTat

Game theory is interpersonal interaction set to numbers --- the mathematics of conflict. Simple games are zero-sum: what you win, I lose. More realistic and interesting are situations where cooperation is possible, games in which:

(Does that sound like life?) Scenarios like this are sometimes called "prisoner's dilemmas"; see, for example, Axelrod's The Evolution of Cooperation.

In simulations it turns out that a modest strategy called "Tit for Tat" is extraordinarily effective. Tit for Tat begins by acting cooperatively and thereafter just echoes back whatever the opposition did in the previous round. Tit for Tat is kind in that if the other player acts politely, so does it. Tit for Tat is responsive in that any attempt to take unfair advantage provokes an immediate retaliation. Tit for Tat is forgiving in that it doesn't hold grudges or remember past slights (beyond a single turn). And Tit for Tat is simple in that it is easily recognized and understood, in contrast to more sophisticated tactics which may confuse the other side.

Tit for Tat is not a bad strategy for real-world situations. Better in many contexts, however, is the more gracious "Tit for Two Tats": turn the other cheek to the first blow, reply only once to the next betrayal, and then try to be friends again. Tit for Two Tats thus adds pacifism to the list of qualities. An accidental misunderstanding (or a little noise in the system) won't trigger a never-ending feud.

So game theory comes down in favor of some quite elementary virtues: kindness, responsiveness, forgiveness, simplicity, and pacifism. They make sense!

(see TwoFaces)

Sunday, October 31, 1999 at 18:00:50 (EST) = Datetag19991031


There was once a contest, in which Tit for Tat won, which was this Prisoner's Dilemma. Each 'player' (program) would choose
either to help the program it was paired with, or to oppose it.
If both players chose to help, they both won small;if one helped
and the other opposed, then the betraying player won big and the
other lost big, and if both opposed, then they both lost some.

What was especially interesting was that, after the contest finished, there was another, which many people entered with either Tit for Tat killers or modifications. The original 'TFT'
writer entered it again, and it won again!

 - Robin Zimmermann - September 24th

TopicScience - TopicJustice


(correlates: TwoFaces, ThirdPlace, BigLessons, ...)