Monthly Archives: August 2006

Where Nash & Diamond can lead you to…

“To see why the pure Hobbesian state is not stable, consider the IPD. Let i, the native, be nasty-never the first to cooperate-so that it alway defects with its clones and its neutral mutants. The invaders are STFT and some nonnasty strategy j. We know that in nontrivial games one can always design a j such that V(STFT,j) > V(ij). So to be uniformly stable, i must punish STFT for doing better with j than it does. But since i is already defecting in every period against STFT, it has exhausted all possible punishments. So no version of i can work. Hence any nasty native can be beaten, and so the corresponding population state of complete defection is unstable.”,
p. 1524, in: Bendor, Jonathan, and Piotr Swistak. 2001. The Evolution of Norms. American Journal of Sociology 106 (6):1493 – 1545.