Today, post-punk is all style. Even its substance – overt political gestures – are a way of adhering to the past. For the surfeit of young bands who play it – whether Radio 4, Bloc Party, the Futureheads, Franz Ferdinand, or the Rapture – it’s an act of indulging in and celebrating rock history, specifically the years between 1979 and 1984, now at a safe distance from the present.

It wasn’t so in 1979, when Gang of Four released its debut album “Entertainment!” History had just burnt to the ground, music history anyway, with a match lit by men named Rotten and Vicious. You can hear the freedom and horror in Gang of Four’s music. The Leeds quartet stumbles out onto this charred landscape like the first survivors to emerge from a bomb shelter.

Realizing they had a clean slate on which to draw, they begin by debating and asking questions. A full quarter century after they began, the original Gang of Four lineup is back together and touring the United States (they come to New York next week), and the questions still resonate in their music: What should rock ‘n’ roll sound like? What is it capable of? How far can it be pushed?

Quite apart from Jon King’s polemical lyrics, the music made demands – of rhythm, of melody, of tempo, of the interplay of parts, of the possibilities between words and instruments. The songs are aggressively deconstructed; the band called it “de-focusing.” The momentum starts and falters, passing from one band member to another.

Each plays an essential role. Hugo Burnham pounds out war-drum rhythms on what sounds like Tupperware; it’s at once aggressive and impotent. Bassist Dave Allen’s weighty, funk inflected riffs refuse their place in the background. Andy Gill answers with discordant sparks off his guitar, and sparse “anti-solos” of absent sound. But for all the effort at undoing, the whole still manages to swing.

If the music was free of history, the lyrics are suffocated by it. The song titles read like political pamphlets – “At Home He’s a Tourist,” “Guns Before Butter,” “It’s Her Factory,” “To Hell With Poverty!” The lyrics appropriate and mock the stiff, clumsy language of theory: Marxist, Feminist, Consumerist, Film.

It was a radicalizing time for the music underground, with Thatcher in England and Reagan in America (or soon to be). But Gang of Four’s music eschewed topicality and straightforward political commentary. Their songs weren’t rants or social anthems, but strident musings on the confusion and helplessness of modern man as consumer, lover, housewife, and breadwinner.

Everywhere he looked, King saw contradictions – crippling, hilarious, terrifying contradictions. He grappled for answers, but found no comfort in the ones he arrived at. “Fornication makes you happy / no escape from society / natural is not in it / your relations are of power / we all have good intentions / but all with strings attached / repackaged sex keeps your interest,” he sings in a flat, jittery voice on the song “Natural’s Not In It.” It’s the sound of a man exhausted of anger but not yet acquiescent.

It’s willfully difficult stuff, jarring equally to the ear and mind. The song “Anthrax” begins with a series of ear piercing guitar squeals (uncharacteristically psychedelic for Gill), then proceeds with two overlaid vocal tracks. One is a fairly typical (for Gang of Four anyway) series of verses about desperation, love, and fear: “Love’ll get you like a case of anthrax/and that’s something I don’t want to catch,” sings King. The other, read in a background mumble by Gill, is a textual analysis of the first and a commentary on love songs generally: “Love crops up quite a lot as something to sing about. Most groups make most of their songs about falling in love or how happy they are to be in love. You occasionally wonder why these groups do sing about it all the time. It’s because these groups think there’s something very special about it, either that or else it’s because everybody else sings about it and always has.”

For a band this hypercritical and self-aware, no decision is simple, let alone the decision to reunite. The band acknowledges that the interest generated by all the neo-post-punk bands played a role in their decision. “I’m mildly grateful” said King in a recent radio interview. “In a way they’ve been quite good at explaining Gang of Four to the world.”

They also note the absence of a radical political voice in rock ‘n’ roll at a time that resembles the one they came up in. But their primary motivation, it seems, is the chance to reinterpret and re-record their own past work. Gang of Four is preparing a new two-disc set to be released on V2 Records. One disc will consist of remixes of classic Gang of Four songs by bands such as the Yeah Yeah Yeahs, No Doubt, the Dandy Warhols, Ladytron, and the Futureheads. The other will consist of reinterpretations of classic Gang of Four songs by the band itself.

The goal is to offer recordings closer in character to the band’s famed live show. Greil Marcus saw it in San Francisco in 1979 and was riveted. “It took me something under five minutes to decide that these left-wing former university students from Leeds were the most interesting band I’d seen since the Sex Pistols – and the most exciting,” he wrote at the time. The Guardian called a January reunion show in Manchester, England, “tremendous,” describing songs as “splendidly monochrome” and “spartan yet thrillingly visceral.”

The new album won’t be out until August, but the first single “To Hell With Poverty 2005” (available now on iTunes) gives some indication of what we can expect. The 1981 version begins with some whistling guitar yelps by Gill, but they’re quickly incorporated into a dance-y Allen-Burnham rhythm. The song supplies the template for all the Rapture’s best jittery disco punk. The 2005 version still grooves, but with a little more swagger and menace. Gill’s guitar holds the spotlight throughout, complicating the fun. Whereas the line “to hell with poverty, we’ll get drunk on cheap wine” sounded insouciant in the original, now it’s bitterly ironic.

This is an interesting approach to reunion, one without a clear message. Even as their acolytes continue to plunder the original Gang of Four records, the band is back to punch-up and up date their old sound. But by focusing only on old material, Gang of Four shows that it, too, is stuck in the past.

In 1980 Marcus wrote of Gang of Four and its post-punk contemporaries that he’d never met people “who so insistently interrogated pop music.” Gang of Four is still asking questions, and that’s still interesting to watch – even if it’s only questions about the band’s own music.

Gang of Four plays Irving Plaza May 16 and 17 (17 Irving Place, at 15th Street, 212-777-6800).