## The Golden Rule as a Prisoner’s Dillema

An old post, but interesting nonetheless. This article describes the Prisoner’s Dilemma, as well as a couple of other classic game theory problems, in layman’s terms. Then, it explains how a very simplistic computer program, when pitted against other programs intended to handle an iterated Prisoner’s Dilemma, performed the best by far. The simplistic program was called ‘Tit-For-Tat,’ and its strategy was to do whatever the opposing program did last. If during the last iteration of the Prisoner’s Dilemma game the opposing program chose to defect, Tit-For-Tat would, in the next iteration, defect. Likewise, if during the last iteration of the game the opposing program chose to cooperate, Tit-For-Tat would cooperate in the next iteration. The interesting part of this, the article states, is that Tit-For-Tat’s behavior enforces the Golden Rule (‘One should do to others as you would have them do unto you’) quite literally.

The interesting part of this article for me is that after Tit-For-Tat won the first round of Prisoner’s Dilemma programs, a second round of Prisoner’s Dilemma programs were created, these all with knowledge of Tit-For-Tat and its strategy, and Tit-For-TatÂ still won. Its creator, a mathematical psychologist, used the results of these contests to develop theories about cooperation and conflict resolution which had applications to, among other things, Cold War relations.

We did talk somewhat extensively about game theory in this class, though we did not discuss iterated games in-depth. I found this article an interesting semi-technical take on game theory, and reminiscent of the discussions we had about mixed equilibria and the ‘football play problem.’ The math would be fun to work out as well (though a blog is not the place to do a bunch of algebra) as Tit-For-Tat’s plays are entirely determined by its opponent’s. In any case, it is interesting to see how even in computer science and game theory, two fields that are relatively far from psychology and other analysis of how humans work, being nice can pay off.

-blox