The most fundamental solution concepts in Game Theory Nash equilibrium, backward induction, and iterated elimination of dominated strategies are based on the assumption that people are capable of predicting others' actions. These concepts require people to be able to view the game from the other...

There is continuing debate about what explains cooperation and self-sacrifice in nature and in particular in humans. This paper suggests a new way to think about this famous problem. I argue that, for an evolutionary biologist as well as a quantitative social scientist, the triangle of two...