People are inherently self interested, and to most benefit ones self, it has been come to by consensus by the majority that you need to do benefit for the wider community in which you rely upon for your own interest. This is always contests to the details but the extreme Libertarianism of Ayn Rand is viewed with laughable skepticism by many who hold the view that an institution, such as Government needs to exist if people are to be looked after within a society.
However clear anomalies exist, which are normally surrounding the idea of Nations, where your sense of responsibility in order to maintain your overall better standard of living, are stretched and throughout history all that can be seen is a strange looking, maybe even slightly different colour, or different style of hat, individual who may take your land, women and resources... therefore violence is the course of action.
I don't believe in Good or Evil, they are just terms that we allot to people who preform certain actions, those which we would want done to ourselves are good actions, whereas those we would not want done to ourselves are evil... or somewhere nearer either side of the spectrum. Due to the construct of enemies, actions we would normally consider evil, done to an enemy is seen as a good, due to the fact you are protecting your group... up to a point. Violence and pain for the sake of it, has often been seen as unnecessary and therefore becomes evil once more.
The truth is we do what is necessary to survive, and enjoy doing so to the best of our ability. We aren't fundamentally good, but self interested... but to have your own interests in mind, we need to be mindful of everyone else around us in the long run.
This is realism, as opposed to cynicism. Cynicism would say that people are dicks because they are.
Realism would say humans are dicks when it suits them and they can get away with it as that's what best suits their interests. Equally they do good because its in their interests in the sense, do unto other what you would want done to you. Not a radical teaching of a genius or a God... simple logic that mankind agreed with at heart at many different locations around the world without cross cultural pollination to aid it.
For obvious reasons I would disagree with Immanuel Kant as I don't think there is a single action done without self interest in mind because encoded into our DNA is our sense of morality, and we merely expand it into our more complex social world... no Moral Imperative exists external to the human body, and even what seem like the most selfless actions make humans feel good, the physical positive feedback which encourages such actions.