Is that what loosens up Joaquin Phoenix in "Joker," allowing him to give what may be the year's most thrillingly unhinged movie performance? Phoenix has shown versatility in everything from the sweet "Her" to last year's vicious "You Were Never Really Here," but there usually is a softness in his performances, an ethereal quality that is almost entirely absent in "Joker." Arthur Fleck, like most of Phoenix's characters, is fragile but also sometimes full of bravado, chillingly still at other times, bizarrely funny (usually when would-be comic Arthur is not trying to be) and always fueled by rage. Director Todd Phillips made a brilliant choice in casting Phoenix, and then he was smart to know that the actor is so deep inside this role that everything he does, up to and including a homicidal rumba, feels right.

The movie is about mental illness, specifically about what happens when a society — Gotham, or maybe ours — cares so little about its citizens that it takes away programs that help them stay healthy (Arthur is on seven unspecified medications). "Joker" pauses to consider how terrifying it would be not to know whether you can trust your own judgment, but when funding cuts force Arthur to go off his meds, he's in so much pain that he convinces himself he has been freed to be the person he always was meant to be.

"The worst part of having mental illness is people expect you to behave as if you don't," he writes in his journal, just before launching a gruesome crime spree that demonstrates that he is done pretending. Cut off from the prescriptions that could treat it, Arthur becomes his disease.

"Joker" wants to tap into the anger of people who feel left behind. Arthur touches off a chaotic revolution of the disconnected, but as far as I could tell, the movie thinks only men are full of anger — or, more charitably, that men are the only ones who think the solution to society's ills is to burn the whole thing down.

The movie isn't even a little interested in what makes its female characters tick. You could argue that this disinterest is a symptom of Arthur's toxicity (the movie is set in 1981, before the term "incel" was coined, but he is one). Regardless, there's no getting around the fact that ignoring half the population is a missed opportunity, especially in a movie that treads as much familiar ground as "Joker."

Many movies have excavated this making-of-a-psycho territory, and Robert De Niro's presence in "Joker" as a glib talk-show host reminds us that he and Martin Scorsese made two of them, "The King of Comedy" and "Taxi Driver." There's nothing wrong with a collage approach to moviemaking and at least Phillips acknowledges the shoulders he's standing on, Christopher Nolan's "The Dark Knight" included. But the lack of originality becomes glaring in a few scenes, especially when, yet again, we see Bruce Wayne's parents murdered, an event that will lead him to become Batman and become Batman and become Batman and — you get the idea.

Not only have we seen that murder many times (the friend who saw "Joker" with me referred to it as "one of the stations of the cross" of "Batman"-adjacent movies) but without spoiling specifics, its inclusion in this movie has no point other than to set up a sequel.

Or is the joke on us? Is it a mistake to expect originality in a movie that features at least the fifth actor in the past few decades to play the iconic title role? Phillips, who co-wrote "Joker" with Scott Silver, doesn't even pretend to go for subtlety here. His movie is all about sensation and passion and ugliness. He forces us to buy into the material before expertly pulling the rug out from under us. And he makes the case that a society that fails to look after the needs of its most vulnerable people is a joke.