If a film's quality is measured solely by its ability to generate audience member discussions about it after the credits roll, then Inception is without a doubt the most successful film of not only the summer but the entire year thus far. Regardless if you think Christopher Nolan's high-concept heist film is a masterpiece, a complete clustercuss or some shade of grey between the two, there's just no walking out of the theater without a desire to discuss it further. A host of adjectives have been thrown Inception's way recently, but forgettable just is not one of them.
So let's take a look at the various discussions surrounding the film. We'll start with a run down of interpretations as to what really happened, followed by an examination of any plot holes that may have gone unexplained by the various interpretations. It should go without saying, but everything below the jump is going to be positively riddled with Inception spoilers.
Interpretation 1: All of Inception is a dream.
(Note: This is the Inception theory to which I subscribe.)
We are never once shown reality. Every frame of Inception is a dream. Whose dream? My money is on Cobb, though it is conceivable that Cobb is simply the subject and that he is in someone else's dream (see Interpretation 3 and 4 below).
There are a number of key elements throughout the film - lines of dialog shared amongst the characters (Mal and Saito both tell Cobb to take a "leap of faith", Cobb predicts what Saito will say in limbo), acceptance of improbable events during segments of "reality" (Saito saving Cobb in Mombasa) - that support the notion that everything is a dream, but for me it all comes down to a simple question: What is our totem? We learn very early on that the one unimpeachable way to know whether or not you're in a dream world or the real world is to test your totem; an item whose behavior only a single individual can identify and predict. In the case of Cobb, it's his wife's spinning top. Arthur's is a single loaded dice. Ariadne's is a precisely weighted chess piece. But what is the audience's totem?
What event in Inception is the audience aware of that no one else can know? There isn't one. There's no point in which reality is clearly and unimpeachably established. The film opens in a dream sequence (Saito's limbo) before transitioning to another dream sequence (Saito's dinner party), which then slides into another dream (Saito's secret apartment). The characters supposedly awaken from that last dream sequence aboard a Japanese train, this presumably being our first glance at reality, but one must ask how the characters arrived from the apartment to the train. There's no visual transition; no shot of "tunneling" from one reality to another. One second we're one place, a second later we're somewhere else, but can you remember how we got there? No, because we're never shown it; we're never shown the awakening process that bridges the two. And not being able to identify specifically how you got from point A to point B is clearly established within the film as a sign that you are in a dream.
That transition, if it existed, would be the audience's totem; it would be the one thing we can cling to, whose behavior we can understand intimately and always predict. By not giving the audience a totem of their own, Nolan has flat out made it impossible to ever anchor any portion of the film as being real versus being a dream.
Now, that's not to say that the movie is ruined if everything is a dream. It doesn't negate the emotional breakthrough that Cobb goes through, which is ultimately what the film is about. In fact, everything being a dream is the ace up Inception'ssleeve: if it's all a fantasy, then there can be no plot holes; the lack of deep characterizations for anyone other than Cobb can be chalked up to the fact that they are all his projections and thus do not require rich histories or distinguishable character arcs. It's basically a catch-all safety net for any complaints registered against Inception's narrative.
Interpretation 2: Everything after Cobb's sedation test is a dream.
If you do not require an "audience totem" to prove that the Japanese train sequence is our first glimpse of reality, then the first moment in the film that begins to shred the line between the dream world and the real world is Cobb's test of Yusuf's custom-made sedation chemicals. After hearing tale of how potent of a mix it is, Cobb goes under to see for himself. After "waking up" we see Cobb in the bathroom, splashing his face with cold water and then spinning his totem. However, he's interrupted before he/us can see whether or not the top falls over.
He then sees Mal through curtains reflected in the mirror. It's presumed that this is one of the early signs that Cobb is losing his grip on what's real and what isn't, but if you combine his impossible vision with the lack of confirmation that the totem behaved as it should and it is conceivable that everything that follows his sedation test is a dream.
If that's the case though, what's the benefit of such a "twist" from Nolan's standpoint? It has no real bearing on the overall story and is thus a less-logical intent than if Nolan had scripted that the entirety of the film is a dream.
Interpretation 3: Saito is the architect, pulls a Mr. Charles on Cobb.
Much has been discussed of deciphering what actually happened in Inception by identifying the layers of reality, but little has been said toward identifying character motivation. Ultimately there are only two characters who have objective-based motivations, Cobb and Saito. Everyone else is either in it for the money or the experience. From this viewpoint alone, everything is either based on Cobb's reality or on Saito's.
Cobb is under the impression that Saito hires him and his team to plant an idea into the mind of a rival corporation, and in turn Saito will arrange for his legal troubles to be cleared away and that he'll once again be able to live happily with his children. We are then under the assumption that the inception being performed is on Cobb's target, Fischer. However, it's not entirely illogical that everything that happens in the film is actually Saito's doing.
It makes some sense if you look at the first three dreams (Saito's limbo, dinner party and apartment) as being orchestrated not by Cobb, but by Saito. He's aware that the Cobol corporation has hired Cobb to steal the information regarding a new plant's opening, so half-way through their attempt to do so, Saito actually pulls a variant of Mr. Charles on Cobb by telling them that he knew about their plans all along, that he knows he is dreaming, and that it was all really just an audition for them to work for him instead. Informing them that they failed the audition plants the initial seed of inception in Cobb's mind; that there is a surefire way he can get home to his children. It is that belief that comes to define Cobb for the rest of the film.
Remember, Cobb believes that inception can work if the idea is born out of a desire for reconciliation. In his case, it's his desire to reconcile with his children that motivates him to accept Saito's challenge of planting the company-dissolving idea in Fischer's subconscious. We can assume that Saito really does want to break up this potential energy superpower, but, other than honor, what reason does he have to make Cobb a free man again? Instead of paying to have Cobb's record completely erased from government records, wouldn't it be cheaper to just create a course of action that leaves Cobb in limbo until his brain scrambles?
It's a stretch, no doubt, and I don't personally think that's what Nolan intended, but there is select evidence causing people to believe this is the case. The most crucial support for this theory being Cobb's trip to Mombasa, which is when A) Saito improbably saves the day by pulling up in a car right when Cobb needs him the most (this last-minute save being a real world continuation of the Saito-Mr. Charles gambit) and B) where Saito interrupts Cobb's post-sedation bathroom trip, where his appearance coincides with Cobb's hallucination/aborted confirmation that he has returned to reality, thus planting the seeds that will eventually lead to Cobb's decision to stay in limbo.
Interpretation 4: Ariadne is the architect/Cobb's therapist.
Hal Phillips' theory that Ariadne is Cobb's therapist and that the real objective of the film isn't to give Fischer an emotional breakthrough, it's to subvert Cobb's deep, deep layers of guilt over causing Mal's death, is even flimsier than Saito as the architect, but it is an intriguing one. I'd recommend reading the full theory right here, but I've extracted the two key paragraphs below to explain generally what is at play:
It's an interesting proposal, that's for sure, but I don't think there's any evidence that this is Nolan's intention; that Ariadne is monitoring Cobb's dreams (everything before she arrives) and then selectively inserts herself at all the key moments to usher him toward the idea that he is capable of letting go of Mal. Also, Cobb being inmate #528491 in an insane asylum is just too much of a stretch (though it is pretty funny).Ariadne presents her dream-self to Cobb as someone who will become his confidant. Because she is a neophyte, he can trust her. Because she relies on his guidance, he is not threatened by her. Because she is a prodigy, she can swiftly "learn" everything she needs to know without contradicting the above. And she is recommended to Cobb by Cobb's mentor and father figure; we are told later that someone's relationship with their father informs the path to their subconscious.
On level 5, Mal shoots Fischer. The film portrays this as a huge problem that can potentially strand everybody in limbo. Not true! It was all part of the plan. Cobb had to believe that his irrational refusal to accept his wife's death had led to disaster, making his problem as urgent as possible. This is achieved when his refusal to shoot Mal, even though he knows she's not real, leads to her shooting Fischer and endangering everybody. The stakes are finally high enough so that Cobb has both a reason to go one level deeper and a reason to sort his problems out, once and for all. (At the very start of level 5, Cobb wonders what's there for Fischer, and Ariadne says "what's there for you?")
Interpretation 5: We do see reality during the film, but Cobb is still in a dream at the end of the film.
I suspect this is one of the most common interpretations of Inception: That the moments that are most likely reality are, in fact, reality (the train ride, Cobb's time in Paris/Mombasa, the plane ride), but at the end of the film Cobb's totem keeps spinning forever, meaning that after he freed himself of Mal's guilt he was finally able to live happily in a dream state where he could be with his family once again.
The biggest piece of evidence supporting this theory is that Cobb's children do not have appeared to have aged a single day since he last saw them. They may even be wearing the exact same clothes, though I'd have to see the film again to confirm this myself (can anyone recall?). We're never told how long Cobb is on the run, but presumably it's for a long-enough period of time that he has exhausted all possible ways of re-entering the country or convincing his children's grandmother-turned-guardian to bring them out of the United States. At their young age, even a year or two of Cobb's absence should bring noticeable growth when he finally sees them "up there", but the change just isn't apparent enough.
Interpretation 6: We do see reality during the film and Cobb is in reality at the end of the film.
If we ignore never being shown how we transition from dream to reality and back again (the audience's totem), then we can accept that the implied moments of reality are indeed reality. What evidence do we have, then, to suggest that the top falls over moments after Nolan cuts to black? Ultimately very little, unfortunately.
The only evidence we're really given is the slight wobble the top develops right before the cut. But until a physicist whose expertise is calculating torque and rotational momentum examines the footage shown and calculates whether it's about to topple over, that's not solid-enough evidence. We can ignore the curious lack of aging in his children, though, simply because Nolan never establishes a time frame between Cobb's departure and return. It's not likely, but it's also not impossible that it's been only a matter of months.
So, really, we have to take this particular interpretation all on a leap of faith...
As for Inception plot holes...
I don't think there are any. But that's because I think everything is a dream and thus any inconsistencies can be chalked up to everything being an imperfect impersonation of reality. However, if you don't subscribe to that theory, there are a few nagging questions I've seen being tossed around as plot holes.
If the dreamer's body's sense of gravity changes and it alters the gravity in their dream, why then does the van's free fall only alter Arthur's gravity in the hotel? Shouldn't the rest of the team suddenly become weightless in the snow covered mountainside (and below)?
You'd think this would be a plot hole, a rather large stretch of the film where Nolan breaks his own established set of rules. However, I don't think he's broken any rule. Yusuf explains that his sedative is capable of keeping the mind's perception of its inner-ear function active, but something Cobb says implies that this may only be true of the first level of dreaming (the one with the falling van). Cobb states that Saito will feel less pain the farther he descends into the dream world. Presumably perception of physical sensation is harder to accomplish realistically within dreams within a dream, so by the time they are three levels down, the imagined weightlessness of level one has no measurable effect on them.
Why is Saito such an old man in limbo, whereas Cobb is still young?
Cobb obviously enters limbo after Saito, thus giving the latter more time to age. Without Nolan establishing an exact span of time between when each enters, it's impossible to say whether Saito is "too old", but a drastic difference is consistent with the events of the film.
How did Mal and Cobb end up in limbo the first time?
A simple question, really. Entering limbo is clearly not the normal threat when in a dream (or even a dream within a dream), but it is a threat to Cobb and his team during their Fischer Inception because they're 'too far under'. One can simply assume that Cobb and Mal took a sedative and entered a shared dream from their living room (kind of like the next evolution of smoking a joint and laying down to listen to music) wherein they, for unknown reasons, died together, thus entering limbo.
How does one wake up from limbo?
We know you enter limbo by dying while in a sedated dream, but it seems like it's really not that big of a deal to actually get out of limbo; you just have to die again. If it's that simple, why is limbo such a threat? How can it ever cause someone's brain to scramble?
The movie doesn't fully explain this point. We just have to assume that one's grip on reality (their awareness that they're in a dream) has to survive long enough for the sedative to wear off. At that point, death will have the same "awakening" effect that it has in a normal dream. However, one may lose their grip while waiting for the sedative to happen, which is the real threat.
What happens if you die in limbo before the sedative wear's off? I have no idea...
If portions of the film are real and Saito is really a key player in the same energy industry as Fischer, shouldn't Fischer have recognized Saito?
It's rather unbelievable that two people could become titans of the same industry and not know who one another are, so conceivably Fischer should have recognized Saito first aboard the plane, and secondly in the hotel within dream level 2 (the appearance of a corporate rival would presumably have shattered the illusion of the Mr. Charles gambit). I suppose the only plausible explanation is that Fischer was so uninvolved in his father's company that he wouldn't know what his competition looks like.
Though, for someone who is rich enough to brag on multiple occasions about how expensive his wallet is, you can assume that Fischer lives in an upper echelon of life inhabited by equally extravagant individuals and thus would be aware of a man like Saito, who is powerful enough and rich enough to buy the airline he always flies. For me, this is just further evidence that everything is Cobb's dream, otherwise this is actually a plot hole.
That's all I've come up with as far as possible Inception interpretations and plot holes go. If you know of any others, please share them below and down the line we can update this post as more concerns roll in. And if I got any details wrong - and I'm sure I did - please correct me below.