There can be considerable overlap between art and philosophy, and not only in the obvious field of the philosophy of aesthetics. In a way, I think the best art is ethical philosophy, and the best ethical philosophy is such a work of art. That statement wasn't clear at all, so allow me to give a very broad example of what I think this overlap can do.
Just before I left Newfoundland, I had a conversation with a friend about what we both took The Dark Knight to be. One of his philosophical interests is post-colonial philosophy, which he shares with me. But I also love Nietzsche, and I've read more of this than he has. One of the things we talked about regarding Dark Knight was its conservative interpretation. Here we have a hero, Batman, who spies on the populace and allows himself to be provoked into torturing a villain, presumably for the greater good. On this interpretation, Batman is a figure who justifies the Bush-Cheney administration, taking on evil tasks to protect the innocent from a terrorist. I definitely think you can interpret Dark Knight in this way, but there's also another understanding of the film that resonates with me, and I think speaks a much more profound truth.
Harvey Dent says, having dinner with Bruce Wayne and Rachel Dawes, "You either die a hero or you live long enough to see yourself become a villain." This phrase encapsulates how I understand Dark Knight. Just because he's Batman, that doesn't make everything he does morally acceptable. This isn't about justification of any action like spying or torture or police brutality. It's about the confrontation of a person who holds himself to be good with the abyss. And when you stare into the abyss, as Nietzsche said, the abyss stares back at you. Where I pick up from there is that when the abyss stares back at you, you have to be strong enough not to become an abyss yourself.
The three characters at the centre of Dark Knight's ethical confrontation that I've just described are Bruce Wayne, Harvey Dent, and Jim Gordon. The abyss, personified as The Joker, forces them to confront themselves, and what they are willing to do to achieve their ends. Because if you go too far, you betray the good intentions you started with. "You either die a hero, or you live long enough to see yourself become a villain." Of those three, Harvey wasn't strong enough to resist the abyss, and abandoned his ideals as he embraced revenge in his final rampage. Everything Harvey did as Two-Face was a surrender to The Joker's will to destruction. He believed everything The Joker told him in that hospital room, and acted precisely according to plan.
Jim and Bruce are strong enough to take up the burdens necessary to sustain their ideals. Bruce refuses to kill The Joker because that would betray his principles about murder. And he and Jim are both strong enough to cover up Harvey's crimes, and maintain the fiction of incorruptibility that keeps hope in Gotham alive.
My post-colonial friend expressed concern when I advocated an ethics inspired from Nietzsche's talk about strength, believing that this kind of thinking leads to fascism, and the triumph of the one with the bigger gun. But the strength I mean is the kind of strength to affirm your life, to overcome petty, reactive desires like revenge and resentment. This is the strength to maintain your ethical stance even in the face of the most incredible temptation to break it.
This strength is value neutral, of course. The Joker refuses to abandon his ethical stance, which is that all are corruptible, and he will corrupt them through fear, terror, and paranoia. The writing style of philosophy proper is working out ethical systems. Grammatically, they are a series of positive statements. Starting from premises about what is good or what standards the good must satisfy, the straight philosopher works out theories and corollaries that elaborate this concept of good. Just read John Rawls' A Theory of Justice as the best example of this I know.
But the actual collision of ethical systems is something I'm not sure this style of philosophizing I've described can help us with. When two incompatible ethical systems collide, can anything settle the collision except war? Are we really faced with what The Joker describes in his last lines in Dark Knight, "an unstoppable force meets an immovable object."? I'm not sure of the answer here yet, but I think stories like Dark Knight offer us a way of understanding these collisions, and how they would play out. The best way to solve this problem of the limitation of philosophy is, I think, to figure out how to combine the philosophical grammar of positive statements with the narrative grammar of the morally ambiguous situation.
I'm certainly thinking modestly here, aren't I?