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Douglas Hofstadter – Metamagical Themas (1985)

TIT FOR TAT fared spectacularly well in the ecological tournament, increasing its lead ever more. After 1,000 generations, not only was TIT FOR TAT ahead, but its rate of growth was greater than that of any other program. This is an almost unbelievable success story, all the more so because of the absurd simplicity of the “hero”. One amusing aspect of it is that TIT FOR TAT did not defeat a single one of its rivals in their encounters. This is not a quirk; it is in the nature of TIT FOR TAT. TIT FOR TAT simply cannot defeat anyone; the best it can achieve is a tie, and often it loses (though not by much).

(About Axelrod’s iterated prisoner’s dilemma tournaments, where the contestants were programmed strategies. The ecological tournament was one that repeatedly eliminated the worst-performing strategies from the pool, so that the ‘environment’ of strategies evolved until a winner came out on top. TfT simply begins by cooperating and subsequently does whatever its opponent did on the previous turn.)

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