What Ethical dilemma does Harvey Dent face in the Dark Knight ?

Harvey Dent wanted to make the wrongs right. He was just going after the people that wronged him. He was in essence a vigilante, like Batman. The only difference is that Harvey didn't mind killing those that did bad things to him. But what made him into the villain was the way he saw the world after his accident. He saw the world as being unfair and that luck was the only thing that was the determinant of good or bad. And he uses luck to justify his actions. After all, heads or tails, whatever the outcome, it's only fair. Harvey's not the one that's deciding if a person lives or dies. It's the coin, or luck/chance itself that is deciding.