This book contains no such chapter. The reason for that is that the Ultimatum Game is stupid, and so is the Prisoner’s Dilemma: these games exist in a context-free, theoretical universe with no real-life parallels. They both posit the idea of the one-shot exchange, a transaction involving two strangers with no knowledge of the other’s identity. In the real world, such transactions never take largely place – we choose to buy things in shops, not from random strangers in the street.