As Foucault argues in History of Madness, there is just a subtle line between reason and madness. Is the madman completely crazy or the sensible one totally reasonable? What parameters does medicine apply to place such a border? Could “madness” have periods of more lucidity than reason?
K-Pax is an interesting film which exemplifies how madness and reason can be easily confused; how the rationality of medicine is sometimes weak as disease. You can find the whole film in Youtube, by the way, please enjoy the English trailer.