Mathematical Conversations

The game of Prisoner's Dilemma is the simplest non-trivial game for two players. It has been studied by game-theory experts for fifty years. So it came as a big surprise this year when Bill Press discovered a new set of strategies which allow one player to dominate the other. The game is taken seriously by evolutionary biologists as a model for the evolution of cooperation in a society of selfish individuals. Press's new strategies give us new ways of being nasty, making the evolution of cooperation more difficult. I will end with reasons for being skeptical of the relevance of this model to the evolution of cooperation in the real world.