Inception has been out for a while now, so I imagine that most people who care have either already seen it or have otherwise been made aware of what happens in it. What's more, my interpretation of the film seems to be the standard one, so I doubt I'm putting anything new out there. Even so, I don't want to be the one to ruin it for anyone, so please be advised: THIS POST CONTAINS SPOILERS. If you haven't seen the movie yet and you think you might, STOP READING NOW.
LAST WARNING: SPOILERS FOR INCEPTION AHEAD
It's the last shot that makes you have to rethink the movie. Until the last ten seconds of Inception, you are basically watching a heist movie. Granted, it's an awesomely executed heist movie with a setting and concept that provide a unique twist on the genre, but at root, it's still a heist movie. And then you get to that last shot. Director Christopher Nolan leaves us with the image of Cobb's top, still spinning on the tabletop where he has forgotten it. The top starts to wobble, perhaps starts to right itself, but before you know whether or not it falls for good there's a hard cut to black.
It was a genius move on Nolan's part, ending the film that way. And what it does is invite you to revisit what you think you knew about what was going on the whole time. We know that Cobb's top is his totem, and that it will only behave like a normal toy and fall over in the real world--in a dream, it will continue to spin forever. Clearly, this final image is meant to get us asking whether or not Cobb is still dreaming in the end.
So, let's assume that he is still dreaming. What then? What can we notice about the previous two hours that might shed some light on things?
The first thing that I thought of is the scene where Cobb is in Mombasa, running away from Cobalt Engineering's hitmen. "Huh," I thought to myself, "It's kind of interesting that they were shooting at him. The only other times we saw anyone shooting at people was in Fischer's mind, where his subconscious projections were militarized due to his anti-extraction training. I wonder if there's any parity there." I reasoned that if Cobb is still asleep at the end of the movie, then he's asleep for the whole movie, so perhaps those hitmen were actually someone's subconscious projections.
That seems a little far-fetched, though. Let's try a different tack: what about the plot structure? As anyone who made it through high school English should be able to tell you, a plot generally consists of exposition, rising action, a climactic moment or scene, falling action, and a conclusion. Obviously there's some variation between different works and authors, but that's the general pattern.
If we look at the plot structure of Inception, then, it's very interesting that the climactic moment of the film is not the point at which the inception job succeeds. No, in fact, by the time we see Fischer enter the strongroom in the Alpine fortress and talk to his dad, the climax has already occurred. The true climax of the film happens one layer down from that, when Cobb realizes that he has to let Mal go.
What this suggests is that the inception referred to by the movie's title is not Fischer's decision to break apart his father's empire, but rather Cobb's decision to finally forgive himself for his wife's death.
This interpretation makes a lot of sense when you consider that Nolan has already shown himself to be the sort of director that is willing to employ an unreliable perspective in his films. Take Memento, for example: by telling the story in reverse, the audience remains as clueless of Leonard's real story as he himself is. Or look at The Prestige, which itself follows the very same pattern of misdirection as the magic tricks it describes--the pledge, the turn, the prestige. In Inception, we're told that the subject can't have any inkling of what's really going on, and that he needs to feel that he's come up with the idea on his own. What better way to hide it from Cobb that he's being worked on than to hide it from the audience?
Given that Ariadne is the only one to accompany Cobb into the lowest level, it would appear that she and Miles are the two who are working on Cobb. If we make that assumption, it makes certain other details become clearer. For example, the given explanation of Ariadne's motivation for drilling into Cobb's past and his issues--that she's concerned with the effect it will have on the job at hand--never quite rings true. On the other hand, if what she's really after is getting Cobb to get over his dead wife, it makes a lot more sense. It would also explain why she's so good at manipulating dream spaces from the start--she's not actually new at it.
But what about the top, you ask? We've seen Cobb spin that top several times to make sure it would fall over, and it did. Ah, but both Cobb and Arthur said that it was imperative that each person's totem was only known to himself, the implication being that if anyone else knew how it worked, they could fool you into believing that the dream is reality. And yet, despite that little gem of knowledge having been given to us, it's never actually used--we never see anyone actually dupe one of the extractors by faking his totem. Anton Chekhov once famously said, "If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there." The fact that we never see a totem being faked could be an example of sloppy writing, but it's also possible that it's a particularly deep example of Chekhov's gun.
There are more clues--for example, Ariadne's name, or the hidden meaning in the film's soundtrack (Google them for more info)--but those aren't ones that occurred to me as I was coming up with this theory. Having heard them now, though, it all does seem to point to Ariadne and Miles planting a seed in Cobb's mind.
The one thing that is still niggling in the back of my mind, though, is the possibility that there's an even higher level of deception at work here. Could it be that, in fact, the movie's real "inception" is something within us, the audience? Could Christopher Nolan be playing extractor to our target, trying to plant an idea within our minds?
Nah, that'd just be paranoid. Maybe.