At a recent benefit show in L.A., Beck proved yet again why he’s so difficult to categorize. Midway through his set, he played “Lost Cause,” a mournful ballad about divorce and emotional isolation. Mere moments after the song began, Will Ferrell wandered onto the stage in a red spandex unitard. He did an interpretive dance and dry-humped Beck’s pump organ. Beck complained at first, reminding Ferrell, “I gotta play that thing, man.” But before long, he went back to singing with the same thinly concealed grief in his voice.

You couldn’t ask for a better (or more confusing) summation of Beck’s musical sensibilities. At one moment, he can be almost unsettlingly vulnerable, exposing the raw nerves of his psyche for the world to see. And then, just as quickly, he becomes a clown again, delighting in ironic detachment and goofy antics. The transition happens so seamlessly that it’s often hard to tell where the honesty ends and the comedy begins, or even if there’s a difference (at least in Beck’s eyes) between the two.

Over the course of eight albums, Beck has provided ample evidence of an artist suffering from multiple personalities. He’s gone from the white-trash rock of Mellow Gold to the earnest folk of Mutations to the silly sex-funk of Midnight Vultures to the down-tempo introspection of Sea Change. His latest, Guero (Spanish slang for “white boy”), marks a return of the “funny” Beck, with its comic rapping and mariachi-style party anthems.

How does he do it? How does an artist go from “Satan Gave Me a Taco” to “Nobody’s Fault but My Own” and back again? How does he write lyrics like “Gettin’ crazy with the Cheez Whiz” and then, just a few albums later, “You gotta drive all night just to feel like you’re OK,” and somehow manage to keep a straight face? Unless the funny songs are really meant to be taken seriously. Or the serious songs are somehow funnier than we realize.

This interview took place by phone, as Beck was preparing to hit the road for yet another world tour. He spoke in a soft murmur, almost a whisper, and he took his sweet time answering my questions. On occasion, the silence dragged on for so long that I was convinced he’d hung up on me.

—Eric Spitznagel

I. IF SOMEONE’S RADAR ONLY GOES AS FAR AS THE BRADY BUNCH, THAT’S WHAT’S GOING TO GET REFLECTED BACK AT YOU.”

BLVR: Your first few albums, like Mellow Gold and Stereopathetic Soul Manure, were made up almost entirely of jokey songs. Were you deliberately trying to become the court jester of indie rock, or...