15 years ago
Society is held together by identification of self in others. We are good to each other partly because we see ourselves in other people. There's also an element of "You scratch my back, and I'll scratch yours" at work here.
Humans are inherently selfish creatures and so what really keeps us behaving is the fact that the status quo serves us better than an unknown quantity.
I hope I'm not going too in depth here, I've just observed people for so much of my life that I think I see it.