‘While We’re Young’ Film spotlights generational gap with wry coupling of Genenerations X and Y

Ben Stiller and Naomi Watts play a couple who discover a new way of living when they befriend a younger married couple in “While We’re Young.”

If you’ve seen Noah Baumbach’s “Greenberg” you may remember a scene in which the title character, played by Ben Stiller, unleashes a tirade against a roomful of 20-year-olds whom he believes have been ruined by sensitive parenting, among other things. (If you haven’t seen “Greenberg,” we need to talk). “While We’re Young,” Baumbach’s buoyant, vinegar-laced new film, is not a sequel ­— Stiller plays Josh, a reasonably pleasant and well-adjusted guy for a Ben Stiller character in a Noah Baumbach picture — but it does pick up where the earlier movie left off in its exploration of the fraught relations between ascendant millennials and the rapidly aging members of Generation X.

Baumbach, 45, does not feign neutrality. “While We’re Young” opens with some darkly funny lines from Henrik Ibsen’s “The Master Builder” that show the hostility directed against the rising generation by the middle-aged to be very old news. How could we not be terrified and resentful? Their evolutionary job is to correct our mistakes, to ignore our hard-won wisdom and to replace us, whether we’re ready or not.

For about two-thirds of its fleet and mostly pleasant running time, however, “While We’re Young” presents a sun-dappled vision of intergenerational harmony. Josh and his wife, Cornelia (Naomi Watts), befriend Jamie and Darby, a 25-year-old married couple who open a portal into a new, cool parallel universe. It’s still New York, but it’s totally different. There are “street beach” parties and ayahuasca ceremonies, artisanal restaurants and thrift shops. Cornelia accompanies Darby (Amanda Seyfried) to a hip-hop exercise class. Josh goes bike riding with Jamie (Adam Driver) and buys himself a narrow-brimmed fedora.

Besotted with their new companions, Josh and Cornelia neglect their old friends Fletcher (Adam Horovitz) and Marina (Maria Dizzia), who seem preoccupied with their new baby. Josh and Cornelia, who decided not to have children after a series of miscarriages, seem to have more in common with Jamie and Darby in any case. And also more to learn from them. These youngsters take an impressive interest in the past: They collect vinyl records, VHS cassettes and manual typewriters, and have a healthy ability to take or leave the latest technology.

Baumbach is, as usual, a piquant observer of the manners and morals of the various demographic subsets of the white, urban lower-upper-middle class. He also honors both of their sensibilities, compulsively combining and repurposing the detritus of the recent past in the hope that some kind of meaning will emerge from it.

The most brilliant example of this lies not in the plot or the decor but the casting. In addition to Horovitz, the movie features Peter Yarrow as a curmudgeonly left-wing intellectual.

I have some problems with this movie, not all of which can be ascribed to the usual narcissism of small differences. But first it’s important to acknowledge the acuity of Baumbach’s insight and his overall generosity of spirit. Generosity, as it happens, is the film’s key ethical principle. It’s the quality Josh most admires in Jamie and Darby and finds most lacking in himself. A documentary filmmaker who has spent most of a decade working on a sprawling, incomplete project on “power in America,” Josh marvels at his young friends’ apparent indifference to success, at their open, eager embrace of experience. He and Cornelia seem crabbed and cautious by comparison.

There is another generational specter haunting them, Josh in particular. He finds himself squeezed on one side by Jamie, an aspiring documentarian guilelessly seeking a mentor, and on the other by Cornelia’s father, Leslie (Charles Grodin), a beloved old lion of the heroic cinema verite era. Leslie stands for an honest, rugged, socially conscious brand of filmmaking that both Jamie and Josh admire. But while Leslie could believe in an ideal of truth in cinema and Jamie can just go out and shoot great stuff, Josh finds himself tangled up in overthinking and qualification. Pitching his unfinished masterpiece to a hedge-fund friend of Jamie’s, Josh is unable to say exactly what it’s about. It’s about so many complicated things, including “the very possibility of making this film.”

And this film, Baumbach’s movie, mostly brings a light touch and a forgiving gloss to its own self-consciousness. It is not afraid to be implicated in the confusion it depicts. But there are also areas where it feels soft and compromised, where the subtlety and clarity of Baumbach’s vision seem to desert him. The last section, while it has a few fine, farcical moments, goes astray in trying to recapture flagging comic momentum and slides toward chaotic Greenbergian hostility. The inevitable complications in what had seemed to be a perfect friendship are not quite credible, and the movie seems uncertain how to handle them.

These tonal and procedural fumblings expose a more serious blind spot. Josh, Jamie and Leslie are all vividly drawn and intricately shaded characters, but Darby and Cornelia, in spite of Seyfried’s quickness and Watts’ incomparable emotional range, are blurry and sketchy in comparison. They have a lesser share in the story.

The frustrations and identity crises that plague poor Josh are large and central. Whatever analogous problems Cornelia might have are circumscribed and peripheral, and exist entirely in terms of her relationships with the men in her life.

Baumbach never quite grants the women in the movie equal access to their own lives, or to the audience’s empathy. His title turns out to be doubly ironic: We’re not really young, and we’re not really “we.”