People being very gung-ho about a particular philosophy, then having their mind changed by experience.
It’s really hard to write a story about a person transitioning worldview because unless the audience is undergoing that same transition when they watch the movie, they won’t be able to identify with both the before and the after.
I mean, there are movies about people undergoing radical changes in outlook, but the audience doesn’t feel what the character feels, because the old philosophy is presented as obviously bad to the audience, and the character is presented as being asleep or brainwashed or something.
What I’m referring to is a character that is actually, fully portrayed as the good guy, in a way the audience believes, who later realizes he was doing bad things, and the audience realized it along with them.
An example of the pattern I’m not talking about is Equilibrium. Christian Bale’s character undergoes a radical transformation of his outlook on what is good, but his previous state (enforcer of the anti-emotion policy) is depicted as obviously bad to the audience.