I had some thoughts of my own about the movie, especially as it relates to fate and free will. It won't make much sense without seeing the movie, and there are some spoilers... so see it!
Each of the movie's 3 main characters (let alone the others, like Rachel, the mayor & Gordon, who offer their own views on the situation) have a different worldtview, which plays into how they respond to terror, coming from being dealt a “bad hand” (Batman’s parents gunned down, the Joker’s abusive father, Dent’s love loss).
Dent sees the world completely through the lens of chance, of fate and causality. By chance he lives another day and doesn’t get shot in the courtroom, and by chance he lives through the Joker’s attack on the armored van. He’ll take his chances. But what irks him is when those chances are coerced by people behind the scenes - as the Joker explains to him in the hospital bed - and then he feels cheated. He goes on a killing spree, but still leaves it to chance (a flip of a coin) whether they live or die; more of a way to absolve him responsibility of their deaths, and instead blame it on fate/the coin.
The other two characters respond different to the theme of free will and fate. Batman continually exercises his free will, fighting on behalf of the innocent/good versus the forces of evil. He believes there is always a choice to fight, yet all the while realizes that he could very well lose everything, and all his efforts might be in vain.
The Joker has the most interesting and terrifying response- he seems to see the world as a terrible place, having lost faith in people (like Dent) in being good. Yet he refuses to believe in fate either, choosing instead to control the situation before him (as Gordon says, the Joker wanted to be caught, wanted to be held in central command so he could blow it up). Ironically, the Joker’s amazing and careful planning ends up creating the most anarchy of all, and everyone else is left in the dust trying to catch up to him.
So as the US responds to terror, do we become controllers and believe that it’s better we’re in control rather than someone else (the Joker), do we become fatalists and believe it’s all just a matter of chance (Two-Face), or do we become believers in the good and choose to fight evil wherever we come across it, promoting good even in the face of staggering odds (Batman)?
Update: For another excellent piece on what the Dark Knight means for us, please see this NYTimes Op-Ed Piece by Johnathan Lethem: "our good faith with ourselves is broken, too, a cost of silencing or at best mumbling the most crucial truths."
