See also Analysis.The Dark Knight Trilogy.
The Joker has a pointThe Joker is, in his own mad way, trying to wake people up. His insanity is an understandable response to the corruption of Gotham City. The Joker has seen what happens when people go along, when police take bribes, when conformity and greed take over, and has responded with anarchy. He has a message that isn't "I want more money now," and that's why he's "a better class of criminal." He's happy to burn the money because he's crusading for what he sees as the truth—that the world is insane, life is pointless and you may as well laugh. He sees humans as people scrabbling for nickels while their houses burn down, and he's gluing quarters to the sidewalk to watch what happens. Perhaps he's right.
It truly is a comic book movie
No matter about the new focus on realism or reviewers declaring The Dark Knight to be a crime movie rather than a comic book movie, these films share several important features with the graphic form from which Batman originates.
The importance of shots and dialogue over shots.
Comics have individual frames with dialogue laced over them. The films mimic this in their execution. There are panoramic shots of Batman standing still on balconies looking over the city, there are Speeches and Monologues placed over shots. The dialogue lends towards too much psychological introspection to be natural (particularly for Bruce) but hey Reality Is Unrealistic and we get the feeling of what would normally be within thought bubbles.
Case in point, the final speech from Gordon with the title drop. It's Talking Is a Free Action in live action.
One should also note, there are a number of uses of the Ironic Echo whether in speech or in shots. It's not unique to comic books but when added to everything else...
- Lots of characters were keeping lots of plans "close to the chest."
Batman is Crazy-Prepared and so are they
There were a lot of Foreshadowing and ChekhovsGuns in Batman Begins and The Dark Knight, all played in rather nicely. They range from the highly important (the sonar phones in the Dark Knight) to the small plays (Alfred's golf clubs). There are even Chekhovs Guns within Chekhovs Guns - if you foresaw the recurrence of the sonar phones, you still might not have noticed Wayne mentioning the government communication intelligence project and if you did you may not have immendiately realised it was the the grand sonar system that shows up at the end. Batman not only knew about the nifty phone gadgets, he came up with a backup plan that incorporated it.
Comic-book science.It's unclear if this was intentional on Nolan and Goyer's part or not, but the much-lamented lapses in accuracy ("Microwave emitters don't work that way! Neither do cell phones! Or sonars! Or third-degree burns!") are completely consistent with the Weird Science that has been a staple of superhero comics since the genre's beginning.
About the "agent of chaos" speech
All too many people have taken this speech as the word of God, even though we know very well Joker is a lying and manipulative sonofabitch. The sole purpose of the speech was to Mind Screw Dent over the edge, and if anyone, Harvey Dent is the true agent of chaos of the movie, because what's more chaotic than deciding one's moral actions by a flip of a coin (because, you know, "chaos" doesn't mean explosions, destruction and violence. It's about indeterminism and literally unpredictability). Joker DID indeed have a plan, though, as his final speech (ace in the hole) confirms. He likely had plans within plans within plans. And if you still don't buy that he could pull it off, there's a simply named superpower for it: probability control.
The Dark Knight is a battle between good and evil, but the good guys are fighting for more than just the lives of innocent bystanders; they are fighting for their very souls. This movie doesn't just show a battle between good and evil, but explores the root of morality as well as why the heroes fight for what's right. It makes the audience ponder the consequences of our morals, or whether they were even real at all to begin with.
The Dark Knight explores the morality of human beings through its characters, with each character invoking different moral perspectives. Harvey Dent was Joker's "ace in the hole," representing The Joker's ideology where morals are just an illusion in a world without meaning; through him, Joker could prove that humans are just savage beasts, and when shit gets tough, they just cut and run rather than stand up for their morals. So, when the purest and most noble of characters fell, Joker could prove how shallow and meaningless morals are. However, the prisoner in the boat acts as a direct contrast to Joker's ideology, and proved that good can come from even the ugliest of places.
These two ideologies of good and evil in this movie can come across as mixed and confused, and it could feel as though Christopher Nolan was confused about what Aesop he is trying to drive home to the audience. However, these mixed messages really just serve as an open debate so that the audience can make up their own goddamn minds; was The Joker right? Are morals just an illusion? Or can good be found in people as seemingly monstrous as the prisoner?
The Dark Knight is a story about duality.
Harvey Dent/Two-Face was the good and evil inside him separated in two. The tragedy that claimed Rachel and burnt half of his face was symbolic of him being torn into good and evil. He became the living embodiment of The Joker's ideology about a cruel world being ruled by chance and chaos. And his coin was symbolic of Harvey's apathy towards morality, with Harvey just leaving fate to make his decisions because he didn't care about what was right anymore, best shown when he said "it's not about what I want; it's about what's fair!" The two sides of the coin represent his good and evil split in two, just like his face.
The Dark Knight is at its core not a battle between Batman and The Joker; it's a story about Harvey Dent the Tragic Hero, and his fall from grace. It's a tale about the duality of good and evil, as you cannot have good without evil, or evil without good. The two of them exist side-by-side in our world, just like Harvey's face after the tragc incident that took Rachel from him and burnt his face.
Bruce Wayne/Batman also invokes this duality, as he lives two lives. He is torn between Bruce Wayne; his desire to lead a normal life, and Batman; his devotion to justice and righteousness.