Less than two years passed between Jonathan Franzen writing a proposal for the 500-plus-page “Purity,” and delivering it to his publisher. For a guy who took several years to heave forth each of his two previous acclaimed novels, that’s practically the speed of sound.

The struggles he’s had in the past that slowed progress weren’t as prevalent this time around, he said. But mortality might also have something to do with it.

“It is unprecedented,” said Franzen, who opens this year’s Talking Volumes literary talk series Sept. 15 at St. Paul’s Fitzgerald Theater. “It may be because I’m not young anymore. Not that I’m better at writing fiction, but there’s less doubt about what I should be doing. When you’re 45 and take 10 or 15 years to write another novel, it doesn’t look so bad. But at 56. …  ”

Reviews have been mixed, but “Purity” has drawn raves from several large media outlets, including the Star Tribune. Notably, chief New York Times book reviewer Michiko Kakutani, who has been dismissive of Franzen’s work in the past, dubbed it his “most fleet-footed, least self-conscious and most intimate novel” to date.

So what’s his fifth novel about? To encompass what it isn’t about might be more efficient. As usual, Franzen weaves sprawling, topical social and emotional themes into the intermingled lives of several key characters.

Pip (real name: Purity) is a young woman seeking answers about her life path and the identity of her father. She travels from Oakland, Calif., and away from her demanding, secretive mother to South America for an internship with Andreas Wolf. The intensely charismatic leader of the Sunlight Project, the East German-born Wolf is dedicated à la WikiLeaks founder Julian Assange to expose corporate and political corruption through subversive use of technology.

The disintegration of a marriage between journalist Tom and his wealthy, neurotic wife Anabel is painfully detailed — and somewhat satirical, Franzen said, though not particularly autobiographical, as some readers might assume given the way his own 1994 divorce fed into his most recent success, the novel “Freedom.”

“Do I know what it’s like to enter into a soul-merging relationship with fervent idealism as a very young man? Yes, I do,” he said by phone from his home in Santa Cruz, Calif. “But the trajectory of Tom and Anabel is invented.

“I think people who have been in really difficult relationships they can’t get out of will find it funny. I’m a comic novelist, for God’s sake.”

Ruled by techno-Stasi

In his fiction, nonfiction and interviews, Franzen has famously, repeatedly railed against what he sees as technology’s influence on the decline of the art of conversation and civil discourse.

“Purity” continues that viewpoint with a running allegory: We are ruled by our techno-devices, and the invasion of privacy they allow, in a manner not unlike the totalitarian state of East Germany before the fall of the Berlin Wall.

Franzen cites Sherry Turkle, MIT professor and expert on technology and the self, for getting to the root of what he sees as technology’s insidious effects.

“We shouldn’t talk about it in terms of addiction, but vulnerability,” he said. “We are extremely susceptible to the seduction of this kind of stimulation. You have to hope that eventually people will tire of it.

“In the same way that you don’t take a drink when you get out of bed in the morning unless you’re a hopeless alcoholic, you might need to set aside part of your life when you’re not online. The crazy optimist in me imagines that someday consumer demand will create the technology to turn off the technology.”

In literary circles, Franzen is as well known for sparking ire with his unvarnished opinions as he is for his success. His most talked-about feud, with bestselling pop-fiction author Jennifer Weiner, was recently restoked when she took to Twitter to criticize comments he made in a recent interview.

Dubbing Weiner “a terrible bully,” he takes umbrage at her continued suggestions that he’s not supportive of fiction written by women.

“You’d think I’d be the least likely white male writer to come in for criticism on feminist grounds, given that half my main characters are female and I’ve been a longtime advocate of writing by women,” he said. “But I think that I’m not the stereotype they want me to be. That’s more angering than if I were the brutish sexist pig they imagine.”

Franzen says he remains resolved to not engage in Twitter wars when such flames are fanned. Isn’t it at least occasionally tempting to respond?

“Not if you don’t read it and only hear about it secondhand,” he said. “Most of the stuff about me personally is utter nonsense, more often out-of-context quotations. But if people are responding without having read what I wrote originally, it makes the problem worse to respond in the same kind of medium. And I can’t fit anything into 140 characters.”

Literary lightning rod

A passionate environmentalist, particularly about bird conservation, Franzen again stirred a frenzy of feather-ruffling with an essay he wrote for the New Yorker in April.

He opened “The Cost of Climate Change” with a reference to the alarm raised by Twin Cities activists that the glass panels being used to build the new Vikings stadium will kill thousands of birds a year. His lament that the enormity of climate-change concerns for the future deflect from taking action on present issues drew strong censure.

What’s his take on why he gets people’s dander up, more so than any other prominent novelist?

“I think there’s a growing realization that an unintended consequence of digital democracy is an enormous amount of self-censoring,” he said. “Social media thrives on divisiveness. An example: People who are strong supporters of art-for-art’s-sake, hard-core literature like to believe that things that are popular are ipso facto not very good. Similarly, people who sell a lot are very dismissive of people who only get good reviews. If you’re actually trying to explore middle ground, paradoxically that’s threatening to both sides.”

In July, Franzen asked an audience at Book Expo to bear with him because he didn’t yet “know how to talk about ‘Purity.’ ”

He’s become a bit more practiced, he said, “but I’m grateful whenever we can change the subject to the digital age. Or climate change.”