Still haven't re-watched it (need to do that one of these days...) but a thought struck me the other day:
Inception seems to have a very rationalistic theory of mind - as if the mind is very organized - if you get down through the security and plant an idea deep enough, that idea can change all someone's life.
I'm not an expert by any stretch, but it would seem to me that the best studies of mind today have come to the opposite conclusion - whether or not one is a rationalist, one's mind is very empirical and tends to base ideas strongly on preponderance of evidence.
As Thomas Harris said, our conclusions are a lump, not a sum.
AKA Context, context, context.