There’s a lot to unpack in “Joker” — about the roots of psychopathy and the thrill of violence, topics director Todd Phillips is unprepared to handle in his oppressively gritty and emptily self-important take on Batman’s greatest nemesis.

Let’s start with the positive, which is Joaquin Phoenix’s no-holds-barred performance as Arthur Fleck, a forgotten man in Gotham City. Arthur feels ignored by his social worker (Sharon Washington), who prescribes the meds he takes ever since being released from Arkham State Hospital, and covers his pain by convulsive, involuntary laughter. He even has a laminated card to explain this condition to strangers.

Having been told often by his mother (Frances Conroy) that “my purpose in life is to bring laughter to others,” Arthur works as a clown for children’s parties and other events, and harbors dreams of being a stand-up comedian. But Mom, in whose apartment Arthur lives, is quickly dismissive. “Don’t you have to be funny?” she asks.

Phoenix puts his all into his portrayal, channeling the self-loathing of an unstable man literally beaten by society and the anger that he transforms into anarchic violence and self-justification. He revels in the physicality of the role, sometimes dancing to music no one else hears.

Much has been written about Phoenix losing 52 pounds for this role, the kind of stunt Robert De Niro used to do to fully inhabit a character. It’s doubly appropriate here, because De Niro has a pivotal role as late-night TV host Murray Franklin — and because Phillips and co-screenwriter Scott Silver base this Joker on two iconic De Niro characters: Travis Bickle in “Taxi Driver” and Rupert Pupkin in “The King of Comedy.”

“Joker” is set in a squalid, garbage-choked Gotham of the late 1970s or early 1980s, when Martin Scorsese directed De Niro in the masterpieces Phillips so liberally references. Like Bickle, Arthur walks the festering streets of Gotham, fiddles with a pistol while watching TV, and becomes obsessed with a mayoral candidate — in this case, billionaire Thomas Wayne (Brett Cullen), whose son Bruce one day will become Batman. And, like Pupkin, Arthur obsesses over Franklin and dreams of appearing on his Johnny Carson-like show.

In another filmmaker’s hands, Arthur’s descent into violence and madness could play as a tragic cautionary tale, a biopsy of a society in shambles. But Phillips — who often caters to the worst impulses of his frat-boy demographic, most famously in “The Hangover” trilogy — seems to be reveling in the chaos unleashed by Arthur and the clown-masked, testosterone-fueled mob that turns his insanity into a movement.

To quote a previous Joker, “Why so serious?” Is this the movie that won the Golden Lion at the Venice Film Festival last month? Or is it just a comic book movie that should be held to the same standard, Phillips recently argued, as the hyper-violent and hyper-stylized “John Wick” movies?

Phillips is trying to have it both ways, playing in Batman’s universe while also indicting the 1% — in the form of Thomas Wayne — for ignoring people like Arthur until their psychoses metastasize. This “Joker” doesn’t care about the violence it perpetuates, but wants credit for pretending to care.

★★
‘Joker’
A new origin story for DC’s clown-faced villain tries to have its violence and comment on it, too.
Where • Theaters everywhere
When • Friday, Oct. 4
Rated • R for strong bloody violence, disturbing behavior, language and brief sexual images.
Running time • 121 minutes