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...

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....