Anatol Rapoport

Anatol Rapoport appears in The Selfish Gene as the author of Tit for Tat, a computer strategy that won both of Robert Axelrod’s tournaments and made reciprocity tangible: it cooperates first, then answers each subsequent move by copying the opponent’s previous one.

Identity and Contribution

Rapoport is identified as a well-known psychologist and games theorist from Toronto. His place in the book is tied to a specific contribution rather than a personal biography: he submitted the winning strategy in the first tournament and submitted Tit for Tat again for the second. The strategy’s success gives his example unusual force in a work examining how apparently cooperative behavior can persist in competitive settings.

The First Tournament

The tournament’s contestants were computer programs—preprogrammed strategies, not human players. Rapoport’s entry was called Tit for Tat and was, in the author’s description, the simplest and superficially least ingenious strategy submitted. It opened by cooperating; after that, it copied the opponent’s previous move.

Against another copy of itself, Tit for Tat produced an uninterrupted sequence of cooperation. Both programs began cooperatively, each then met the other’s cooperation with cooperation, and both received the full benchmark score of 600 points. The result made the strategy’s defining feature visible: its cooperative opening could sustain mutual benefit when met by the same rule.

Repeat Victory and Its Limits

For Axelrod’s second tournament, contestants had the first tournament’s results and analysis available. Some responded by submitting nice and forgiving strategies; others expected many competitors to be forgiving and tried to exploit them. Rapoport again submitted Tit for Tat, which won with 96 percent of the benchmark score. Nice strategies generally did well: all but one of the top 15 were nice, while all but one of the bottom 15 were nasty.

The second result also set a limit on what could be inferred from Tit for Tat’s success. The exceptionally forgiving Tit for Two Tats would have won the first tournament had it been entered, but it ranked well down the second tournament’s list, where subtler nasty strategies could prey on its softness. A strategy’s standing therefore depended on the other strategies in the field, not on an unchanging quality that made one rule best in every setting.

Significance in the Argument

Rapoport’s repeated victory supplies an empirical example for the book’s discussion of cooperation among self-interested strategies. Tit for Tat does not begin by exploiting its opponent; it offers cooperation and then responds to what the opponent has done. Its tournament record thus supports the argument that reciprocal cooperation can prosper without requiring universal altruism, while its vulnerability to more calculated exploitation shows why generosity and forgiveness are not sufficient in every strategic environment.

The author uses the tournament results to turn from rankings among submitted programs toward the broader question of how strategies fare in relation to one another. That question leads into the idea of an evolutionarily stable strategy: success depends on the surrounding population of strategies, and a rule’s outcome cannot be assessed in isolation. Rapoport’s entry is therefore both a memorable tournament winner and a bridge between computer competition and the book’s evolutionary analysis of cooperation.