(As with my Hulk piece, the following is not a general review of all aspects of the Chris Nolan THE DARK KNIGHT movie (2008): the type where I say that I liked Gary Oldman's centered performance or disliked Christian Bale's Billy-Bat-Gruff take on the Batman voice. This is essentially a look at how the director of TDK chose to respond to various elements of the Batman mythos in translating it to the cinema-screen.)
"What is impossible yet probable is to be preferred to that which is possible yet incredible."-- Aristotle, THE POETICS.
Aristotle doesn't detail what he considers to be "impossible" in the Poetics, but as he's not opposed to the presence of gods in serious drama and epic-- only to their use in the "deus ex machina" form-- I imagine that any events or beings that have a tinge of the metaphenomenal would meet this criterion. (Aristotle's favorite play, OEDIPUS REX, sported such an event in the form of an oracular prophecy and made reference to assorted fantastic beings, ranging from the gods themselves to the monstrous Sphinx.) But the first part of the quote makes clear that even the seemingly impossible should obey laws of probabilty. To my ears this sounds a lot like modern science-fiction's "one-gimmee" rule: once a writer begins a tale by introducing a strange phenomenon-- what Cioffi calls an "anomaly"-- into an otherwise-stable setting, afterward that writer is expected to observe laws of probability about how the anomaly acts and what it can do.
Conversely, in the second part of the quote, Aristotle is taking issue with writers who are willing to toss out any improbable event for their audience on the theory that it is remotely POSSIBLE, even though not probable. Aristotle clearly considers this psuedo-realism to be far more of a cop-out than invoking gods and monsters to serve as elements of the dramatic action.
Which brings us to the Nolan DARK KNIGHT. The fantasy of a costumed, high-tech vigilante operating at will in a modern metropolis is essentially an "impossible thing" which the Batman concept asks you to grant, irrespective of whether the hero battles fairly-probable versions of real-world criminals or other "impossible things." Here the metaphenomenality obtains not from a showier form of fantasy, like Superman juggling suns, but the equally-far-out idea of Batman possessing a ninja mojo so insuperable that a whole city of cops and criminals can't suss him out. But once the audience grants this impossibility, one should expect that within the parameters of that fantasy Batman acts according to some laws of probability. Often in melodramatic action films those laws may get a little bent-- say, in BATMAN RETURNS, the hero. framed for murder by Penguin, goes through considerable trouble to expose the villain's perfidy but somehow forgets to get himself exonerated on the murder-charge. But Nolan's DARK KNIGHT not only breaks the laws of probability, he even calls attention to his doing so, as if counting on his audience to ignore what he says and pay attention only to the characters' hyperbolic emotionalizing.
Nolan's primary plotline in TDK bears some similariry to Edward Zwick's 1998 film THE SIEGE, in that both concern a major metropolis reduced to chaos by the threats of terrorism-- by Islamic fanatics in Zwick's film and by the mad menace of the Joker in Nolan's. But Nolan's approach to the terrorism of the Joker is to tie it into a motif of renunciation throughout both TDK and Nolan's earlier BATMAN BEGINS. Almost as soon as Nolan's Batman begins being Batman in the first film, he seems eager to quit the whole racket, and he seems even more so in TDK. Along comes the Joker, who starts a spree of systematic killings and claims that he'll keep it up until Batman reveals his identity and surrenders himself to police-- presumably to be killed one way or another once Bruce Wayne is out in the open.
Batman's initial response makes all the sense in the world: "There's no proof that the Joker will stop killing," or words to that effect. And yet, perhaps 30-40 minutes later in the picture, Bruce Wayne suddenly becomes willing to make the Great Sacrifice to supposedly stop all the killing.
Now, this development is an example of Aristotle's "possible yet incredible" device. It's certainly within the bounds of POSSIBILITY that Bruce Wayne could lose his mind and submit to the Joker's whims, even having stated that he doesn't believe his surrender will stop the Joker. But it's certainly thoroughly IMPROBABLE, especially coming from someone who's supposed to be smart enough to maintain his Bat-secret from the criminal hordes, etc.
To his credit, Nolan manages to shuffle his cards fast enough that many viewers don't get a chance to see Wayne go through with this incredible dopiness, because Wayne's crimefighting colleague Harvey Dent stands up and claims that he is Spartacus (or something like that).
Now, the basic plot of the villain who threatens innocents to subdue the hero is not itself at fault. It is conceivable that one could engineer a situation in which Batman faced a villain whose grudge against the hero was so specific that, yes, Batman could believe that that villain would stop killing innocents once Batman himself was out of the picture.
But Nolan doesn't come close to attempting even this level of probability, and given the many other sloppy, overblown scenes throughout TDK, I'm reasonably sure that probability was far from his thoughts. Like many, he may have thought that the existence of an impossibility in a film granted a writer to banish the probable as well.
Given the space I've just devoted to just aspect of the movie-- albeit the most central one-- I should probably close this up and make my further thoughts on it as a Part II--