You are strapped to a chair. The doctors, your family and friends standing around you say you are insane and need to be committed to an asylum. What test/reasoning can you give yourself to prove to yourself you are sane. And that this situation might be an elaborate deception/fraud?

I've always wondered if there was a mental/logical test that a person could give themselves that would prove they were not insane despite everyone else telling them they were.

Edit: Took out the reference to the movie in which this question was inspired. Not hard to figure which one it is if you've seen it already.