What a word, “decline.” It’s directional: downward. It’s deferential: no, thank you. It connotes judgment, disappointment, and death. Movies can be about decline or symptomatic of it. Paul Thomas Anderson luxuriates in postlapsarian decline, the moment after Adam and Eve bit the fruit and we all exited Eden. “No, thank you” becomes “Yes, please.” Yes to crime, yes to pornography, yes to irrational love, yes to the charlatan who has invented his own religion. The wayward son succumbs to the dying father, the earth succumbs to the oil magnate’s drill, disparate strangers succumb to the songs of Aimee Mann. Anderson’s the sort of director I’ll follow down. He has a comfort with collapse and lowness. He was, after all, raised in a valley.

His seventh movie, Inherent Vice, is based on Thomas Pynchon’s seventh novel and is utterly postlapsarian. JFK, MLK, and RFK have been shot. The Manson trial is under way. Nixon is in the White House; Reagan is in the governor’s mansion; we’re in Los Angeles in 1970. But this isn’t that kind of movie — not something grand and heavy about Who We Are. Maybe it’s about Who We Were, but even then Anderson isn’t forcing an idea. Anderson compartmentalizes decline by genre — it’s a detective film, a stoner comedy, another look askance at the LAPD. Anderson is going for comedy that leaves a residual sadness.

It actually begins blue, with trouble coming to the movie’s private investigator, a human pot brownie named Larry Sportello (Joaquin Phoenix). He keeps an exam office in a medical clinic, so everybody calls him “Doc.” But he couldn’t be shaggier if he were on Scooby-Doo. Doc lazes from one piece of Los Angeles furniture to another. Life’s a sofa. He’s dazed, barely able to keep pace with the present action, which is weird for a private investigator — even a “doper” who lives in a shack near the perfectly made-up Gordita Beach. In fairness, the present action never moves in a direct line. This is one of those Philip Marlowe–style Southern California yarns in which a beautiful woman traipses into and upends a detective’s life. Somebody’s dead or disappeared. Here, it’s the latter. The woman is Doc’s ex-lady, a blonde named Shasta Fay Hepworth (Katherine Waterston). She used to be a hippie, like him. Now there’s a beach volleyball vibe about her.

She’s mixed up in a plot against her married lover, a Jewish real-estate tycoon who is surrounded by white-power dudes ruining the city with atrocious developments. The tycoon’s wife and her lover want Shasta to help declare the tycoon insane so they can take his money. Shasta’s heard that Doc’s been dating a lawyer (Reese Witherspoon) in the DA’s office. Shasta wants to know, can the lawyer help? I’m inclined not to trust a woman who shares her name with budget soda. But the melancholy she introduces in Doc seems real, even after she has slipped into her Cadillac and driven off. Anderson seems OK to see her go. He puts on Can’s “Vitamin C,” brings up the title in slanted neon, and for almost two hours of the film’s 148 minutes, lets it ride the groove of the song’s jungle-surf. All the film’s comedy follows it.

Doc sets out looking for clues. Sometimes clues find him, like when a Black Panther and ex-con (Michael Kenneth Williams) drops by his office. Doc stops by a desert massage parlor run by a spicy Chinese American Valley girl named Jade (Hong Chau, who’s beyond wonderful). The place has a bad Gauguin nude painted on a door, which has a smaller door where the vagina is. Jade introduces herself through that. On the other side, presumably, is a Tarantino movie. Doc tells her he’s looking for an Aryan biker. “Does he eat pussy?” she asks, as if she were a waitress, as if it were a food group. Doc winds up knocked out, placed next to the body of the guy he’s looking for, and is taken in for the guy’s murder by Detective Christian “Bigfoot” Bjornsen (Josh Brolin), the LAPD’s Renaissance detective (he investigates, he acts, he does car commercials). A lawyer (Benicio Del Toro) gets Doc off so he can keep trying to unpack Shasta’s case.

Doc puts on a suit (a costume, basically) and drops in on the tycoon’s wife (Serena Scott Thomas), who glides in from a pool party, dressed for future widowhood, in a black cutout bathing suit, heels, and webbed veil. In a moment of mighty absurdity, the camera gets her in a tight, Norma Desmond–y close-up, and she asks in a posh English accent that matches the oily clench of her face, “Do you like the lighting? Jimmy Wong Howe did it.” The woman who brings the drinks drops the tray on the glass table with hilarious imprecision. By the time Doc gets to Penny, his lady at the DA’s office, she’s heard about Shasta’s return and is feeling only sort of helpful.

Where’s this going? How do these people relate to the main mystery? What is the main mystery? After 30 or so minutes, there are so many missing people and strange syndicates that you need a diagram that not even Pynchon’s book provides. What kind of stoner movie is this, anyway? Is detective work even possible when you’re this baked? It can be done, the way Denzel piloted planes drunk and high in Flight, but you can’t rely on yourself. The plot keeps coming at Doc. He tries to keep up, but he would have an easier time wrapping bonbons with Lucy and Ethel in that candy factory episode. Pynchon was dealing in bygones — eras, lingo, people. Some of the satire in the novel was verbal; some of it involved shifting the sudden permeability of fixed social taxonomies: Jews in bed with Aryans, Aryans in bed with black militants, hippies in bed with the government, the government in bed with everybody. It was as much an orgy as it was a societal collapse.

Anderson’s strategy for capturing Pynchon is to roll him up and smoke him, until the smoke passes on to you and some confusion and conflation set it, until it’s all just Paul Thomas Pynchon. In the opening scene, the singer Joanna Newsom appears as Doc’s artsy pal. She stands in a low-angled shot and narrates the setting, using lines from the novel. By the time Inherent Vice is over, she has gone from talking over the movie — sketching background details and conjuring states of mind — to talking to it. The densely polished joshing of the book becomes a hazy, bleary movie farce. Being stoned here is a joke. But so is lucidity. Anderson doesn’t overdo the high. This is as much a druggy wild goose chase as The Big Lebowski, but he opts not to make being stoned an extravagantly surrealist experience. To that end, people vanish and materialize like smoke, the frame speeds up toward the end of coked-up scenes. But it’s never over the top. It doesn’t have to be. Whether it’s sex or love or pot, everybody’s on something. Drugs aren’t special. They actually are a food group. In one of the movie’s few moments of casual surrealism, Bjornsen gobbles a tray of marijuana like a cartoon bear.

The way Brolin does it is scary-funny. His lower mouth moves up and down over a serving tray. He might finally know he’s more dangerous as a sideman. His comfort with weirdness, with lunacy, is his secret weapon as an actor. He’s playing an idiot here, one who seems to sense a threat to American masculinity. He acts the part like a tank with no superego. His turret is constantly looking for something to shoot. Phoenix finds another beat in his teen-man persona. It’s rarely the same thing with him. Everything brilliant about him here is throwaway stuff: The look of nausea on his face as Brolin fellates a frozen, chocolate-covered banana. His humming and singing in reaction to important details. This is a straight-man part that Phoenix plays more or less in exclamation points and yoga poses.

Waterston is as inconsequential an actress here as a lot of women who showed up as sexual figments in actual 1970s movies were. It’s like she was cast from a lifeguard’s chair. It’s not glumness she’s bringing to her scenes with Phoenix (he does that), it’s torpor. The rest of the great big cast is almost uniformly excellent: Witherspoon, Williams, Scott Thomas, Del Toro, Owen Wilson, Jeannie Berlin, Yvette Yates, Maya Rudolph, and especially Jena Malone, as a former junkie turned counselor whose husband (Wilson) is mixed up in this mess. She serenely tells Doc about her graphic bottoming out, like some angel in an episode of The Rockford Files.

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I’m open to the complaint that Inherent Vice is all indulgence. It might be too much in Robert Altman’s thrall, even unconsciously. Anderson seemed to have shaken the influence in The Master, but the new movie is almost directly in dialogue with Altman’s aired-out detective film The Long Goodbye from 1973. Martin Short shows up as a doctor for a quick, cartoonishly vulgar scene in the middle, and he’s been styled to look like the doctor Henry Gibson played toward the middle of Altman’s film. Both movies are dolorous, but Anderson can do more with it than Altman does. Anderson is a stronger director now than he was in the late 1990s. He can use influences without falling deeply under them. His movies are cousins to other directors’ rather than clones.

A couple of months ago, someone told me a story in which Anderson came up in conversation between two Hollywood studio executives. “How did I get stuck making a Paul Thomas Anderson movie?” one asked. The other replied: “Because it’s your turn.” The charitable interpretation of that exchange is that no one wants to be the studio that denies someone like Anderson a home to make movies. Profitability isn’t his aim — nor his problem. Neither is prize-winning. But even if you claim not to get his movies, he’s among the country’s best film artists. Let him make his art.

For now, even as the industry sinks into a superhero-movie hot tub, Hollywood has the prestige of Anderson’s movies with which to play hot potato, alleviating its guilt about its thriving mediocrity. His films happen to be worth every dime they don’t recoup for a studio, including Inherent Vice, which isn’t even going for the moon the way There Will Be Blood and The Master were. This is as much low-stakes entertainment as Pynchon’s book was.

There are, of course, two ways to experience Inherent Vice: with the brain on or the brain off. Both work. The latter is a good time, the former more illuminating. The determination to follow a plot might get you only halfway to satisfaction. The underlying context is fixed, though. What drought was to Chinatown, real-estate development is to this movie: a background crisis.

Pynchon is the movie’s source material, its engine. But Anderson’s version of Pynchon’s Los Angeles doesn’t feel far from Joan Didion’s rumination on it in The White Album. They’re both about “inherent vice,” which refers to items that are uninsurable because of their unstable nature. It doesn’t typically apply to people. But decay brought on by the combination of social culture and human nature are at the heart of Pynchon, Anderson, and Didion.

Didion’s book collects a dozen or so years of essays written during her stints in California from 1968 to the late 1970s. She’s there for all the upheaval and transition, which she captures with detached humor and spooked perception, a ghost observing a cultural cemetery. Anderson’s movie is more pop than Didion’s essays are, but a spiritual lament unites them. Anderson is imagining the moment that mainstream culture and counterculture began to permeate each other.

The couple of times Doc walks into police headquarters (he’s not on the force or anything), Anderson has the beefy officers passing by knock into him and glower at him in disgust. The decline? To them, he’s it. You can tell from the ’50s jawlines and crew cuts that law enforcement is hating every minute of 1970.

Didion took an interest in the mechanics of cool — the delusions, denial, and compromises that revolutions needed to keep going, whether they were made by Eldridge Cleaver and Huey P. Newton or the Doors. Anderson reframes compromise as a cop-out that was sometimes necessary and sometimes pure hypocrisy. Distrust and disillusionment crystallize over and over in Didion’s dispatches. With Anderson, a soft stench of paranoia wafts through everything. It’s the glare of headlamps that leaps from the rearview mirror and onto your face. The past, the man: They’re on your back. Anderson can have a movie work both ways. It’s a director blowing smoke on one hand and making smoke signals on the other.