Are we selfish?
Economists like to say that, to a first approximation, we are. In other words, that we tend to seek to maximize our own rewards, in a more or less rational manner.
The trouble is that this theory (at least, a straightforward interpretation of it) doesn’t describe how people behave in many situations. For example, given a sum of money and asked to decide how to split it between themselves and an anonymous stranger, most people choose to give some of it away. This scenari