Joaquin Phoenix meths it up.
Phoenix is Freddie Quell an alcoholic vagabond who by chance meets Lancaster Dodd, leader of philosophical movement The Cause. The two become entwined in a strange love/hate, father/son, envy/admire relationship.
Initially Freddie is an experiment for Lancaster, who sees him as unevolved mentally. Lancaster often remarks on his animal nature "laughing is an animal response" and has taken it upon himself to teach/break Freddie of his alcoholic and base human urges. In a stand out scene he performs a bewildering session instructing Freddie to walk back and forth across a room alternatively touching the window and then the wall. As the viewer this scene is relentless and Joaquin gets so method he smacks into a table, leaps up and nearly impales his head on a lamp.
Freddie is disorder but openly so. Lancaster while on the surface appears to have all the answers is the one living the lesser life by living a lie, constantly struggling against emotions like anger, frustration and lust.
Paul Thomas Anderson apparently based The Cause on Scientology. I once watched a dvd donated to the library that turned out to be a Scientology recruitment film (FYI if you donate items to a library they will end up at staff homes because a) it costs too much to incorporate them in the system and b) there's no room on the shelves) It basically hinted at having the answers to why we're so unhappy even though we're all good looking and wealthy (not aimed at me then) As for similarities to The Cause, both founders have written books and are concerned with reincarnation and raising people to a higher state of being but the director is really just sampling aspects it's not a treatise. The Cause like Scientology and like all cults is ultimately about deluded men being creeps and having multiple wives.
Paul Thomas Anderson has made a complex and beautifully cinematic piece of art - ambiguous the way good art should be.
YES - I'd sure like to try some of that rocket fuel but hold the paint thinner
