Aristotle once said that man is a "political animal." He did not mean that we instinctively form voting blocks. What he meant is that human beings are fundamentally communal: they come together and form families, and many families come together to form communities, and many communities come together to form the city, the "πολις". Nations and empires also emerge from this ascension, but what also emerges is what we call "civilization," an ordering of human conduct and affairs around our communal instincts. Whether in the home or in the city, there is (or ought to be) a general sense of deference to those who share the space with you. We all belong to the city; we are all in this together. To be "civilized" is to respect your fellow man as a member of your community; to act otherwise is to go the way of the brute, the savage.
For millennia, civilization was thought to be a good thing, or at least better than barbarism. Heaven was often viewed as the place of ideal order and community, and thus Augustine lauds The City of God, while Charles Williams' Arthurian poetry contrasts the Christian image of Logres with the pagan wildness of Broceliande. The key to all of this is the idea of order: order is good, while chaos is bad. In the Christian worldview, the whole of existence is built on the order that is Christ (Col. 1:17), and the city (with its inherent civilizational bent) was meant to be a concrete emblem of that order, of Christ, of heaven itself. Thus, order was beautiful, order was true, and order was good, and thus so was the city.
Not everyone agreed or agrees with this idea. There have always been anarchists and extremists who view order as the height of oppression. Ovid's subversive narratives in the Metamorphoses, the barbarism of the dark ages, Romanticism's revolutionary poetry and practices, anarchical terrorists at the turn of the 20th century as well as postmodern deconstruction at its end: history is full of those who would see order fall, fail, die trying. They have existed alongside and in tension with civilization, and the howling debate between the two rages on to this day: is civilization good? when and how does it become destructive? ought it to be defended? how ought we to defend it?
One of the most recent voices in this debate (I believe) has been director Christopher Nolan and his Dark Knight Trilogy (henceforth, DKT). Ostensibly a set of Batman films, Nolan's work has been lauded for legitimatizing the "superhero" film as a genre capable of true cinematic quality and narrative depth. It was not just his move towards realism (as opposed to the visions of Burton and Schumacher), but also the serious substance that he gave to his films: they proposed intriguing scenarios, asked interesting questions, and provided powerful (and sometimes controversial) answers. One such scenario was the various dangers that can threaten the "city" (viz., Gotham, which comes from a nickname for New York City), which lead to questions about the inherent goodness and defense of civilization itself. I believe that Nolan's answer to this scenario and subsequent questions is that the "city," while far from perfect, is good and ought to be defended against all extremists.
DKT is full of extremists, some more easily recognized than others. Of course, the Joker is the most obvious example. The self-described "agent of chaos," he sees "these civilized people" as monsters just like him: their "moral codes" (i.e., the deference towards others that creates civilization) are all flimsy facades, "dropped at the first sign of trouble." Unique in his anarchism, the Joker is not out to destroy the city but rather prove that it is already destroyed: we maintain the illusion of civility and order, but "when the chips are down, [we'll] eat each other." Thus, for the Joker, the city and civilization are not just bad; they are a "bad joke," and he feels called, like an unholy prophet, to point us all to the punchline.
The League of Shadows is a unique kind of extremism. Whereas the Joker sees civilization as so meaningless as to be illusory, characters like Ra's al Ghul and Bane see civilization as so paramount that they will destroy any and all that do not meet their ideal standard. Thus, they will "bring justice to Gotham," but it is justice in the void, cut of from any other balancing virtue (such as mercy or wisdom). They are so sure of Gotham's irredeemable corruption that they will not simply destroy it; they will let it destroy itself, whether through "fear" or revolution (two highly corrosive elements to any civilization). There is a certain satanic allure to both their and the Joker's extremism: civilization is often messy and imperfect, and the drive to burn it all down and either start afresh or just "watch the world burn" can become irresistible to those who have lost all hope for the city.
It is indeed possible to lose hope for the city, but it only comes when you first give in to another kind of extremism, an extremism that is far more subtle, and if you weren't watching the films carefully you would've miss it. I am referring to the extremism of characters such as Officer Jonathan Blake, Commissioner Loeb, and (most significantly) Harvey Dent. This is the extremism that says that the city ought to be defended, but its defense must always play by the rules of the city. Thus, Commissioner Loeb wants the "vigilante" known as Batman "off the streets," and Blake always works inside the system (often with an air of pretentious self-righteousness). In their world, the rules are the city, and to work outside of them is to not only defy civilization but also (in effect) fundamentally deny it. As Blake tells Gordon, "You've betrayed everything you've stood for." Why? Because Gordon broke the rules.
Gordon is an excellent counter-example to this, as he (and Batman) are there to teach us the hardest lesson of all: if you would defend the city, then you must get your hands dirty. This is a hard truth for many (esp. Americans) to swallow, but it is an incredibly necessary and relevant hard truth. When you run into people who "don't want anything logical like money," who "can't be bought, bullied, reasoned to, or negotiated with," you have to take them down for the good of the city. Furthermore, you must realize that more often than not "the systems fail" you (as Gordon says), and "the rules aren't weapons anymore, they're just shackles, ways for the bad guys to get ahead." In those moments, you have to do what needs to be done (what "needs to happen," as Batman puts it), not what will look good on paper. Gordon stated it perfectly to Dent: "I don't get political points for idealism. I have to the best I can with what I have." If you do not have this balanced view, if you succumb to the extremism of the system, then you will fall when the system inevitably falls.
Harvey Dent is the prime example of this fall. As Gotham's district attorney, he is the system, but he has balance in the beginning. He's willing to turn a blind eye to Batman's "outlaw" activities, mainly because they're accomplishing the goal of taking out organized crime (a cancer on any civilization). But he still believes that "we can be decent men in an indecent time," and when he discovers that there are those who will use your systems against you (as the Joker tells him, "I took your little plan and turned it on itself"), he falls into madness and despair. As Two-Face (the hypocrite, the law turned criminal), "the world is cruel, and the only morality [i.e., civilizing deference] in a cruel world is chance," i.e., chaos, the flip of a coin. This is what the extremism of the system does: when it fails (and it does fail), you run the risk of falling with it. (It is important to note that Officer Blake avoids this fate.)
One special case must be mentioned, and that is Alfred. In Batman Begins (BB) and The Dark Knight Rises (TDKR), he too is an extremist (albeit a sympathetic one). In the beginning, he fears Bruce's transformation into Batman is mere "thrill seeking" (a "taste for wanton destruction" as he says in TDKR), and in the end he wants Bruce to give up Batman and work with the police, instead of around them. There are two ironies at work. The first is that he sees Batman as an extreme action when, in fact, Batman is the proper balance (as we'll see). The second is that some of the best statements on that balance come from Alfred, all in The Dark Knight (TDK). This film is unique in that when faced with the Joker, even Batman feels the pull towards the extremism of the system: he will turn himself into and cooperate with the police because "I see now what I have to become to stop men like him.... Batman can't take this." It is Alfred who pulls him back from the brink:
B: "What would you have me do?"A: "Endure, Master Wayne. Take it. They'll hate you for it, but that can be the point of Batman. You can be the outcast. You can make the choice no one else can make: the right choice."
Alfred understandably forgets his own advice by TDKR, as his concern for Bruce overcomes his understanding of Batman. Nonetheless, for one moment (or film) at least, he did understand the "point" of Batman: the police don't need Bruce Wayne to work with them; they need Batman to work around them, doing what they can't do, going where they can't go, being willing "to plunge his hands into the filth so that you can keep yours clean" (as Gordon tells Blake).
Batman's "point" is to be a paradoxical balance. He is the defender of the city by going outside its systems. He ensures the success of justice by breaking the law. He only has "one rule" (i.e., he won't kill: "I'm no executioner"); any others are expendable. "At what cost?" we may ask along with Lucius Fox (a man also tempted by the extremism of the system). To that question, Batman gives no answer then, but he does later to Gordon: "The Joker cannot win." That is the view Batman maintains (through great struggle) throughout the trilogy, and it is the balanced view. The Joker cannot win; the extremists must not win. The city is good, and it must be defended, even if it takes drastic steps (like "burn[ing] the forest down," as Alfred puts it). That is the messy yet necessary paradox that Batman embodies.
Batman is for the city, for civilization, and he is for it against all comers, willing to even take its reproach in order to save it. ("You either die a hero, or you live long enough to see yourself become the villain. I can do those things.... I'm whatever this city needs me to be.") The greatest image of this comes in the climactic battle in the final film. Bane, in seeking to "bring justice [i.e., destruction] to Gotham," has started a pseudo-revolution between the haves and the have-nots. Batman mounts his offensive against this extremist activity, and he does so with an army of police officers. This is significant because the police are symbolic of the city; their name even comes from the word "πολις". So when Batman faces down the extremists one last time (because he cannot stand by "while my city burns"), he does so with the literal embodiment of the city itself, all uniformed, marching as one, in defense of civilization.
It is fitting that when Batman is presumed dead at the trilogy's end, Gordon reads a passage from A Tale of Two Cities(!), a passage that could very well summarize the Batman credo, and the credo of all who would defend civilization:
I see a beautiful city and a brilliant people rising from this abyss. I see their lives, for which I lay down my life, peaceful, useful, prosperous and happy. I see that I hold a sanctuary in their hearts, and in the hearts of their descendants, generations hence. It is a far, far better thing that I do than I have ever done. It is a far, far better rest I go to than I have ever known.
This is the final logic of all defenders of the city, of the dark knights and the watchers on the wall: we defend the "beautiful city" because of the "brilliant people". The city must be defended, for the city is good because people are good. It is not necessarily a moral goodness (for we are all sinners), but an ontological goodness: we are, and we make and commune after the image of our Creator. To attack the city and the civility that it stands for is to attack people per se; to attack people per se is to attack God per se, and that is the greatest anarchy, and evil, of all.