http://en.wikipedia.org/wiki/Intentional_fallacy

Har har.

I think you basically need to choose the type of world you want to write about–in my mind, this question of magic brings about two distinct possibilities. Either the world is sacred or it’s secular. If you want to have some sort of moral element to yr magic, you gotta go the route of Lewis, Tolkien, Dickens, Rowling, Kipling–they create universes where actions beget moral repercussions, even if they don’t seem to at first. This is not to say that everyone always gets what they deserve, but in general there are demarcations between good and evil, and actions fall into one of those categories.

Conversely, your universe could be based on the idea that morality is irrelevant to actions and their subsequent consequences. This doesn’t necessarily mean that characters can’t act in moral ways, just that the framework of the universe isn’t based on good / evil distinctions. Examples of this can be seen in all those goddamn D & D novels, or Conan, or Vonnegut, or Dick, or Alan Moore’s stuff. Again, that doesn’t necessarily mean that they aren’t redemptive or morally whatever, just that the world they exist in is ambiguous toward good and evil.

There are probably shades of gray in there that I haven’t bothered to find. Maybe this is useful?