There's a naive school of thought, popular (for reasons I don't fully understand) among moralists, that says we should be nice to each other because it's the "right" thing to do — because God is watching, for example.
A much more interesting school of thought says that you should be nice to other people because it's good for you. Even if you're entirely selfish, your best strategy is (often) to be nice to others. Help them. Add value to their lives. And this will come back to benefit you — not in some supernatural karmic way, but because all the people you help will help you, somehow, in turn. This is how prestige status works.
Here are some of the guises in which this idea hides:
- The Boy Scout rule: Always leave the camp site better than you found it.
- Service leadership.
- Competitive altruism.
- Noblesse oblige. Note that traditionally this is cast as an obligation, i.e., a moral obligation. But a more enlightened understanding is that you can't be on top (and stay on top) unless you're helping the people below you. Parasites are eventually extinguished.
- YC: "Make something people want."
- Paul Graham: The Ronco Principle. (HT: Patrick O'Shaughnessy.)
- Silicon Valley: "Make the world a better place."
- "What can I do for you?" "How can I add value here?"
- Generosity and helpfulness as virtues.
- Holding the door for others.
- Zahavi's Arabian babblers
- Wealth: The Toxic Byproduct
- The Economics of Social Status