Immanuel Kant, Adam Smith, Charles Darwin, George Williams, and Stephen J. Gould, among others, have pointed out that observing that a certain behavior causes a certain effect does not itself license the inference that the effect was the result of intent or design to bring about that effect....

The one-state machine that always defects is the only evolutionarily stable strategy in the machine game that is derived from the prisoners' dilemma, when preferences are lexicographic in the complexity. This machine is the only stochastically stable strategy of the machine game when players are...

This paper explores the quantitative relation between non random, assortative matching and the maintenance of cooperative behavior under evolutionary dynamics. We consider a population of individuals who are \hardwired" to play either cooperate or defect. They meet other individuals according to...

This paper introduces a model of social preferences featuring a single parameter representing an individual's disposition to share resources with others. The parameter reacts to observed behavior of others in a clearly defined manner. Therefore, the model allows the numerical analysis of...