In transforming the life of the brilliant mathematician John Forbes Nash Jr. into a muzzy, triumph-of-the-human-spirit Hollywood movie, Ron Howard and his collaborators have stripped it of anything that might present the audience with the slightest discomfort or reason to think about the documented facts concerning Mr. Nash. On its own terms, though, the movie succeeds in dramatizing Mr. Nash's mental illness and, to a lesser extent, his mathematical insights. Russell Crowe's performance is honest and focused, but the movie's conceptions of intellectual life and human character are ultimately so simplistic, so deeply mistrustful of the audience's intelligence that any chance for genuine insight is squandered.