In Jesse Peretz's Our Idiot Brother, Paul Rudd plays Ned, a kind of Upstate New York version of “The Dude” Lebowski — a man out of time, blinkered enough to be living the hippie dream. In the film's first scene, Ned is “entrapped” into selling pot at a farmers market to a uniformed police officer, and is swiftly sent to jail.

As stupid as Ned may seem from the get-go, Brother doesn't want us to write him off as an actual idiot. Selling pot to a cop is obviously dumb, but it's also the result of a genuine, selfless faith that other people are not only as pure-hearted as he is but also that when they talk, they're actually saying what they mean.

After being released from jail, Ned enters a world in which slippery language covers for adaptable notions of right and wrong, and the process by which he realizes this — and even tries to good-naturedly fight against it — is the movie.

Postprison, Ned discovers that his longtime girlfriend, Janet (Kathryn Hahn), has taken up with a new dude, rendering Ned both homeless — which he seems more or less prepared to roll with — and also estranged from his beloved dog, Willie Nelson, who Janet insists is rightfully hers, seeing as the drifter who left the pooch at their place was her friend.

Determined to reunite with his dog but first needing to get back on his feet, Ned surfs the couches of his three sisters in the city. First, dowdy mom Liz (Emily Mortimer) offers her brother pocket money in exchange for minding her young son and assisting her documentary filmmaker husband (Steve Coogan), a pompous sleazebag who uses his camera as a key into his subjects' pants. After Ned's oblivious ways burn that bridge, he ends up at the bachelorette pad of Miranda (Elizabeth Banks), a high-maintenance, low-scruples would-be reporter working on her first big assignment for a glossy magazine. Ned's guileless naivete causes problems there, too, and soon he's crashing with his bi-curious hipster sis Natalie (Zooey Deschanel), at the loft she shares with her lawyer girlfriend Cindy (Rashida Jones, masculinized in shorts and bow ties, in a costume department's ludicrous notion of Williamsburg butch). Would you believe that Ned is doomed to screw up this cohabitation, too?

This rarely laugh-out-loud dysfunctional-sibling comedy is in some sense a family affair: It was directed by Lemonheads bassist-turned-filmmaker Peretz from a script by his sister, Vanity Fair contributor Evgenia Peretz, and her husband, documentary-filmmaker David Schisgall. If it's intended as a roman à clef of the clan's actual dynamic, it's more narcissistic than comically incisive or revealing. Coogan's husband is a cartoon villain, and Miranda, the character who would seem to be informed by Ms. Peretz's professional experience (she said in an interview that Graydon Carter “suggested some changes to make it more realistic”), is defined primarily by her hairstyle and addiction to fro-yo. (Banks does have nicely barbed chemistry with Adam Scott, playing a cynical love/hate interest in a subplot given too little time.) And with the movie siblings given no father to speak of, there's no counterpart to the Peretz family patriarch, former New Republic editor Marty — a shame, as the elder Peretz's tendency toward controversy (rumored to be not-so-secretly gay, blogging slurs against Muslims) could have given this film some much-needed dramatic friction, and maybe even forced some semblance of the real world to bleed into its bourgie bubble.

The few direct lines drawn by the filmmakers to their real lives are all the more striking because Our Idiot Brother does such a half-assed job of reflecting the ways in which real people communicate. Its roundelay of shallow types (played by beautiful movie stars) treating one another badly, and having whiny conversations about said treatment, is such a whisper-soft version of social critique that it makes the autobiographical films of Nicole Holofcener (Please Give, Friends With Money) look as cutting as the films of Jean Eustache.

And then, it gets worse: In the film's final act, the Ned character is revealed as a patent device to teach everyone around him the lessons that will transform them into Better People — to the point where the character exits the city with the line, “My work here is done!” That may be Our Idiot Brother's one gift to the indie ensemble-com canon: In allowing wayward white people to find salvation from a selfless outsider-drifter-saint who is actually part of their own bloodline, the film gives permission for a genre already prone to solipsism to finally close in on itself entirely.

OUR IDIOT BROTHER | Directed by JESSE PERETZ | Written by DAVID SCHISGALL and EVGENIA PERETZ | The Weinstein Company | ArcLight Pasadena, ArcLight Sherman Oaks, Fallbrook, Monica

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