Here are a number of reasons why altruism is often rational:

I. People can value altruism for its own sake:

1. Intrinsic values: as a psychological fact, most humans intrinsically value at least some things as ends (not merely as means to other ends) that are not about their own gain. For instance: people may value the reduction of suffering around the world or the flourishing of the people in their country. 

2. Warm glow: most humans find that it gives them happiness to do altruistic acts. I call this “the Lucky Fact” about human nature. It’s both important and very lucky (i.e., it didn’t necessarily have to be this way if our evolution had taken a different path). We feel good to see positive feelings in the people we like, and we feel good about ourselves when we cause good feelings.

II. Genuine altruism is also instrumentally useful:

3. Evolution: there are multiple reasons evolution programmed most of us with genuine altruism, even though it optimizes for gene spread.

Altruism is rewarded in settings of:

i) raising children

ii) iterated games

iii) tribal loyalty, with punishment of defectors

iv) deception detection

4. Relationships: altruistic people tend to have stronger, happier, more goal-aligned, and mutually beneficial relationships. Although, in theory, a purely selfish person can have highly beneficial relationships, it is much harder to make these expedient tit-for-tat relationships work.

5. Pre-commitment: suppose that there was a world of highly rational, purely selfish beings. If they were able, they might pre-commit (jointly, as a group) to become partially altruistic as a way to help solve difficult collective action problems. By uniting goals, they mutually gain.

This piece was first written on December 27, 2020, and was first released on this site on February 25, 2022.