So the big question: when Cobb finally gets back to his kids, is it reality or a dream?
The top spinning at the end is the Schrodinger’s cat paradox. Without seeing it fall, but having evidence it might, we are left with the fact that Cobb’s world is simultaneously a dream and reality. More importantly, Cobb’s action to walk away without confirming the top’s fall is the true point. The confirmation of reality doesn’t matter. Just as Fisher is told a lie in the dream (that dad loved him and wanted him to be his own man), we learn that a well meaning delusion is much more valuable than a bleak reality and neither is more real than the other. Fisher’s new life based on his father’s approbation will lead to some very real consequences, even if those consequences are limited to Fisher rectifying his relationship with his father. He is no longer trapped by a perception of what his father wanted. No longer trapped by the perception he disappointed his father and thus must work to (though he never really could) live up to the dead man’s standards.
Cobb had a commitment to the real world when Mal was alive, which is why he tricked her to snap her back into the real world. But once Cobb has his catharsis with Mal in limbo, he realizes that even objective reality isn’t necessarily the most important thing. Remember, early in the film, Cobb spin the totem in “reality”, such as it is, and leans a gun against his head. He’s planning to shoot his brains out if the top doesn’t stop spinning. That is how paranoid and obsessive he is. What he doesn’t yet know is it doesn’t matter.
Cobb’s guilt over his wife plagued him whether he was in a dream or in reality. It’s that guilt that truly kept him from his kids, not the charges. Many other writers have noted there was a bunch of ways Cobb could have got back to his children, even convincing grandma to bring them to Europe. He could have found other ways, but the fact was he couldn’t face his kids, not even in a dream, due to his guilt. In the end, in absolving himself of the guilt, Cobb realizes it’s rectifying your inner reality, not the outer one, which is most important. With this movie we get bogged down by questions of what is and what isn’t concrete reality and that is all beside the point. It’s only the reality of one’s own mind that matters. The reality you believe to be is the only reality that exists. And that’s why he walks away from the spinning top at the end. Cobb knows full well totems aren’t reliable, he used one to trick Mal. He could easily create a dream concept of a totem that can fall. In the end he chooses his kids (i.e. he chooses to move on) over the certainty of the totem. Wherever he is, his inner turmoil is over, and that’s the most reality he can hope for. By letting the haunting memory of his wife go, he has become truly “awake,” whether he is in a dream or not.
Just saw Inception last night, but my theory is fully half-baked.