Karma. I like to think that if you throw some out there, it will come back. So far, it seems to be true. Plus, helping other's, seems to be human instinct. dilligaf
One of two things. "inclination" or "duty" In the sense of Kants groundwork of the Metaphysic of morals. He lays it out quite nicely.
Merely due to having compassion and empathy for others who are suffering. I know I feel that way when I go out of my way to helping other people but this is just my thoughts alone.
Because the government makes us of course! If not for them people would eat each other children then watch porn....with no roads of course
Psychology, and the golden rule. Life isn't fair, but you can adjust the odds a bit, by being patient with discipline. If you are recompensed constantly by any type of action, whether good or bad toward any individual, good or bad. Then evidently, the best way around anything is to adjust the way you see yourself and to treat everyone as you yourself wills to be treated.