What Does The Ending Of Shutter Island Really Mean?

Ending Theory #1: An Elaborate Experiment On The Innocent Teddy Daniels

Teddy/Andrew's status as a guilt-ridden Ashecliffe patient appears obvious in the closing minutes, but there may be reason to believe Teddy Daniels is - as he believes for much of the film - just an innocent being toyed with after all. Given the period, a time in which the US government was genuinely carrying out dangerous tests on American citizens without their knowledge (see Project MKUltra and the Tuskegee syphilis study), and considering the numerous mentions of human experimentation within the film, things do occasionally point that way. That would all appear to be moot following Teddy's final flashback and admission of guilt at the end, but knowledge of the director still leaves room for doubt. One interesting thing about Martin Scorsese is that he shoots films from his characters' point of view, to such an extreme that his films Taxi Driver and The Wolf Of Wall Street, to name two examples, have been accused of racism and excessive irresponsibility. Really, Taxi Driver and The Wolf Of Wall Street only appear racist and uncaring because they're taken from the perspective of a bigot and a sociopath, respectively. It's possible, then, that Shutter Island has too been misinterpreted by critics, with the film's 'official' version of events actually the vision of an innocent man who's been convinced he's insane through a combination of medication and psychological suggestion. It could be that the government is continuing its 'experiments' with Teddy Daniels's trip to Shutter Island, playing an overly-elaborate game with Daniels (Noyce calls Teddy a "rat in a maze") in order to see if they can trick him into manufacturing his own doom. The film is so paranoid, so mistrustful of authority and the US government that an establishment conspiracy can't be completely ruled out.