We may think about merging this with the "Are humans Inherently Evil?" thread.
http://www.ultimatemetal.com/forum/philosopher/415039-humans-inherently-evil.html
But to discuss the topic a bit...
Evil constitutes a certain moral depravity. Since morals are constructions of the human mind and don't actually exist without human cultivation and conception, it follows that there is no such thing as evil. Evil actions are things that human beings judge objectively "wrong." But there is no objectively "wrong" situation. There is only what affects you, and what doesn't affect you. Now, life isn't this simple, because we also have to take into account the fact that we are living in a world with other human beings, and it often serves our best interests to live peacefully and compatibly with our kind. So, even though "right" and "wrong" may not exist, there is still what a man should and shouldn't do from a logical, rational perspective.
I've written this as though it is the cold, hard truth. It isn't. It's just what I believe. And I know lots of people here will probably disagree.