The Mental Hospital
Sure, the movie takes place mental hospital, but it might sometimes make you wonder how much the rest of the world works the same way as the hospital does. Is it all that different out here?
After all, the mental hospital is a world where your life is controlled by people in authority and where you get punished if you act too much like an individual. In some ways, you could say the same thing about modern society.
The mental hospital is built on the idea that pure routine and strict rules are the best things for people with mental problems, as Nurse Ratched reveals when she says "The best thing we can do is go on with our daily routine" even after one of the patients commits suicide.
In other words, the whole setting is based on the assumption that the human brain can't function properly if it's left to itself. As we hear one patient ask Nurse Ratched, "Are you saying that it's sick to want to be alone?" The whole place is designed never to give you any private time to just sit and think, because apparently this is antisocial behavior that's bad for your sanity. But try telling that to someone with a strong sense of individualism, like R.P. McMurphy.