Although we’re not usually aware of it, the world runs on social agreements. Red lights don’t stop cars. They stop because our society agrees that (a.) intersections are dangerous places and traffic needs to be regulated, and (b.) when we see a red light facing us, we need to stop in order to avoid possible death or serious injury.
I use that as an example because, in order for social agreements to work out, there also needs to be a degree of enlightened self-interest involved.