It's absurdity at its best.

Rating: 1/10 (27 July 2010)

Philosophically it was absurd. Here were the main points I gathered from it:
 Faith and doubt are discussed, but the conclusion is that having faith doesn't matter because you can't know what's real anyways. What did the Japanese businessman's non-faith avail him or di Caprio's character's faith avail him? They both ended up having the same destiny, no? So, freewill is an illusion, too.
 Skepticism is the only valid approach to life.
 Existentialism is true; we really do make life to be whatever we want it to be. Top remains spinning at end, or does it eventually topple? Was it dream or reality? Who knows? Does it matter? No, existentialism says we can define our own reality to our liking.
 Relativism of truth: i.e., truth is whatever you make it up to be.
 Subjectivism / idealism / Cartesianism / Kantianism, i.e., ideas are all that are real. If the senses are to be 100% distrusted for determining what is real, we might all be as insane (possessed) as the Dark Knight's Joker.
 Objective reality, for all practical purposes, does not exist. Every subject just makes up his or her own reality. This leads to solipsism and ultimately a suicidal nihilism.
 Murder can be justified as long as the person you are killing is someone's "projection." Di Caprio's character snipes men in the snow scene to the architect girl's surprise; he justifies this by saying they are just another man's "projection."
 Magic potions (i.e., potent drugs) are the solution to anyone's problems.
Christopher Nolan should brush-up on some real, Aristotelean-Thomistic philosophy, but then maybe the movie would not have fooled the audience into thinking it is profound instead of absurd. There were good parts—the importance of fatherhood and family, for example—but they were overshadowed by ambiguity for the sake of ambiguity.
Also, artistically, it could've done without most of the car-chase and shooting scenes and confronted more head-on the philosophical issue it was raising, i.e., "What is real? What is being, existence? Etc," rather than hiding its ignorance in a silly plot scheme involving "kicks," "inception," and other Freudian, postmodern rubbish. If it were 1 hour shorter, it would have still been the same: absurdity at its best.