NEW YORK (AP) ― “If you’re trying to assign the trait of maturity to us, frankly, it won’t wash.”

A conversation with the filmmaking brothers Ethan and Joel Coen has only just gotten started when Ethan, quite gleefully, puts a stop to any discussion of growth, evolution or development.

Now in their late 50s, the Coens have a host of awards, including best picture for their tense, bone-dry Cormac McCarthy adaptation “No Country for Old Men.” Their last film, the much Oscar-nominated Charles Portis adaptation “True Grit,” was an unexpected box-office hit, earning $250 million worldwide. Somewhat shockingly, they are ― to use the much sought-after label in their “O Brother, Where Art Thou?” ― bona fide.

Their latest, the folk music tale “Inside Llewyn Davis,” continues the trend of awards-season releases with more realism than, say, the screwball of “The Hudsucker Proxy” or the surrealism of “The Big Lebowski.”

The Coens don’t dismiss the trend. They just predict its imminent expiration date.

“If you’re trying to make a developmental statement about us,” Ethan explains, “it might not ... ”

“It might not stand the test of the next movie,” says Joel, finishing the sentence. They chuckle with tickled delight, like boys who are getting away with something, at the thought of their next opus.

For now, there’s “Inside Llewyn Davis,” the latest zag in a career full of wholly unpredictable hopscotching through noir (“Blood Simple,” “Miller’s Crossing”), farce (“Burn After Reading,” “The Ladykillers”) and less categorical quandaries (“A Serious Man”).

Tracking the Coens is, famously, a fool’s game. What leads them down Los Angeles bowling alleys? Or into a ’50s-era barber shop? Aided by the Dave Van Ronk memoir “The Mayor of MacDougal Street,” they arrived at specifically 1960-61 Greenwich Village for “Inside Llewyn Davis” because it exists on the cusp of history, ahead of Bob Dylan’s arrival.

Oscar Isaac stars as the title character, a folk guitar player and singer whose beautiful playing is contrasted by his foul-mouthed, cynical downtown life, which he spends hopping from couch to couch, gig to gig. The Coens, with T Bone Burnett, fill the film with full performances of less famous songs from the era, all but one of which was filmed live (rather than to playback).

On a recent fall afternoon, the Coens granted an interview with the Associated Press at their Tribeca office, a narrow three-story apartment with editors working on the bottom floor on a concert documentary of the movie’s music, to air on Showtime on Dec. 13. To accommodate a reporter, Ethan lugged a chair up to the small top-floor perch where the brothers brainstorm and script.

From here their movies are born, generated from the pingponging between their similarly imaginative, comic minds.

“We were just sitting around the office talking about nothing, as we do, and (Joel) said, ‘OK, supposing it begins in an alley behind Gerde’s Folk City and somebody beats the (expletive) out of Dave Van Ronk?”’ says Ethan, while Joel laughs. “That’s the beginning of what movie?”