Many scholars turn to emotions to understand irrational behavior. We do the opposite: we turn to rationality and game theory to understand people’s emotions. We discuss a striking theory of emotions that began with the game theory of credible threats and promises, then was enriched by...

We investigate in an economic experiment how people choose sides in disputes. In an eight-player side-taking game, two disputants at a time fight over an indivisible resource and other group members choose sides. The player with more supporters wins the resource, which is worth real money....

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....

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....

Experiments show that people give money away to other people, even when contributions are anonymous. These findings contradict the common economic assumption that people maximize their own payoffs. Here we take the approach that human altruism is shaped by a set of cognitive models for distinct...