The movie plays on the tension between civilization and barbarism. It basically accepts a psychology in which human beings are inherently sinful. Society establishes structures and procedures which keep our sinful nature in check. Without the veneer of civilization, our lives, in the words of Thomas Hobbes, are “nasty, brutish, and short.” One of the ironies of civilized life is that controlled violence (in the form of police, the military, or a superhero) keeps the barbaric forces at bay.
The Joker sees the inherent contradiction and concludes that civilization is simply a sick joke. We wear a painted face with a smile that hides the dark truth about our nature. He spends the rest of the movie chipping away at the façade. He goads the District Attorney, the police, and Batman to show their true colors. Standing in front of a burning pile of money, the Joker states, “This town deserves a better class of criminals, and I’m going to give it to ‘em.” Even the criminal who is motivated by greed is inferior to the one who realizes that civil society is farce. After all, the money desired by the petty criminal is in fact a product of civilization. As Bruce Wayne’s butler, Alfred, observes, “Some men aren’t looking for anything logical. He can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.”
The Dark Knight explores the same issues that many war movies, police dramas, and even some westerns take up. How can the civilizing forces of violence fight the bad guys without becoming the bad guys themselves?