Andy Warhol: The man who gave the 21st century its flavour

If you seek his monument, look around you. Look at television shows such as Big Brother, which is Orwellian in title but thoroughly Warholian in ethos, and goes a surprisingly long way towards realising his flip, notorious prophecy that "in the future, everyone will be world-famous for 15 minutes". (Sincere question: why does "world" usually end up lost when that phrase is cited?) Look at all the celebrity rags, the Hellos! and the OKs! and the Peoples and what have you, all of them the direct heirs of that gushing, utterly uncritical mode of interview pioneered by Warhol's Interview magazine. Look at the youngish stars of our local arts scene, better known, like the old Factory crowd, for their naughtiness and their adverts and their restaurants than for any notable quality of their oeuvres. Look, any night, at the crude ironies and distant atrocities and craft-less vacuities that flit across your television screen... Why, this is Andy's world!

Not completely, to be sure. A world dominated by the avowed values of Andy Warhol – or, more correctly, of that strange conceptual art-work known as "Andy Warhol" – would be one in which any form of critical commentary beyond "gee" or "fabulous" would be taboo (instead of simply pushed to the margins of public discourse), and Posh and Becks would fill even more column inches, and sceptical jokes about them and their glitzy kind seem blasphemous or merely baffling. Anxious European intellectuals of the last century, from Spengler to Bergman, foresaw the threat of dehumanization and warned against it in dense tracts and dark parables: it took a deadpan New World wag like Warhol to twig to the fact that some people might rather fancy being shallow, that numbness and blankness might come to seem desirable life options.

Indeed, to write anything but gossip or gush at all about Warhol is, implicitly, to fight a form of rear-guard action against his influence, since he did as much as any single person to propagate that peculiarly modern brand of Stoicism that regards overt caring – about culture, about values, about anything much except money and glamour – as a bit gauche, a bit earnest, a bit, in the argot of the early Sixties, square. To the hoary question "But is it art?", for example, the true Warholian reply is not "Yes, because..." or "No, because..." but "God, you're such a drag". That, or a simple elevated eyebrow.

Still, if his tastes have not altogether triumphed, it would be hard to deny that 15 years after his premature death – on 22 February 1987 in a New York hospital, after a routine gall bladder operation – Warhol fits even more snugly into our culture of celebrity than he did in the Sixties and Seventies. And, as he would have been pleased to learn, he's as familiar a name as he ever was: a major retrospective of his entire career, bringing together over 150 paintings, drawings and sculptures, opens at Tate Modern next month. It's a phenomenon all the more striking when you consider how the other gurus and culture-heroes of his glory days are doing in the intellectual stock market. Herbert Marcuse: all but forgotten. Buckminster Fuller: ditto. Marshall McLuhan: a few flurries when the internet came in, but largely remaindered. Timothy Leary: minor joke. Frantz Fanon, Julian Beck, Jerzy Grotowski, Gregory Bateson: who?

Maybe Warhol's posthumous liveliness is proof that he really was part-vampire after all, as the denizens of the Factory implied when they gave him the pet name "Drella" – half Cinderella, half Dracula. Or maybe he was indeed the prophetic genius that his most ardent apologists claim, the one visual artist of the 20th century who seriously took on the implications of living in an age of mechanical reproduction and so made himself into something vastly bigger, if not aesthetically better, than protean Picasso or harrowing Bacon or cosy, comforting Andrew Wyeth. Or maybe he owes his enduring lustre to the fact that he was the supreme huckster, the one selfproclaimed artist fully meretricious enough to gain global attention in a dim and yobbish post-culture.

Square talk, all this, but as Mondrian might have said, there are squares and squares. Square one: it's possible, and honourable, to despise Warhol's work as trash and regard his legacy as baleful. Such, roughly, was the position of the late Peter Fuller in his most Ruskinian phase. Square two: it's possible, though admittedly it takes some doing, to back up Lou Reed's claim that Warhol was the greatest artist of the 20th century or any century; such, roughly, is the territory occupied by Arthur C Danto, the eminent American philosopher and art critic. Square three: it's also possible, and fruitful, to think that Warhol's significance is a matter of both/and rather than either/or – both prophet and symptom, both real and fake, both cad and innocent, both Dracula and Cinderella. And one way in which these opposites can be harmonized, if not fully reconciled, is by dwelling on a single four-letter word beginning with "F": fame.

Fame is the primary thread through the confusions of Warhol's life and work: it was his obsession, his desire, his subject matter, his working tool and, in 1968, when Valerie Solanas took aim and fired, almost the death of him. Whatever else about the man may have been phoney, it would be a kind of madness to deny that his fame was real. As the Marxists used to say (Marxists, especially German Marxists, doted on Warhol, since they had somehow persuaded themselves that he was satirising capitalism), it is not by chance that he made his first career breakthrough in the sphere of advertising, and you would be daft to underestimate his sheer brilliance as a publicist. Or his shamelessness. As one of his biographers points out, people tended to be baffled by his ability to be in the papers almost every day until they learnt the very simple secret that he employed a very good, very expensive press agent.

The early milestones of Warhol's progress all involve the mechanisms of publicity. In 1955, still working exclusively as a commercial illustrator – much in demand for his technical facility, hard work and inventiveness – he was hired to produce an ad campaign for a shoe company at the then remarkable salary of $50,000 a year. In 1958, the shoe campaign won him the industry's equivalent of an Oscar, and had his ambitions run in that direction, he could have been an extremely rich ad man for the rest of his life.

But ad men are seldom famous, not in the way actors and singers are. Andy had other plans. As a sickly child, he had written to Shirley Temple asking for her autograph, and he never lost that early awe for stars and stardom. In his own bid for stardom, he hit on two initial areas of concern that were both (fairly) original and (dazzlingly) far-sighted. Every résumé of his work as a painter points out that his first full-scale exhibition was the Campbell's Soup show of 1962, with 32 images of the 32 nutritious flavours on sale for 100 bucks a shot. Not every résumé underlines the fact that, at the most elementary level, the attractiveness of these images, their sheer easiness on the eye, owes a great deal to the unsung creative helots in the branding departments who had designed a label that tired consumers would want to lift from the shelves. Warhol made these paintings himself – not something he would always do – but they were already a kind of collaborative work.

His second ploy, and second block of subject matter, was made public in the portraiture he did from 1963 onwards: Elvis, Marilyn Monroe, Liz Taylor... the Mona Lisa. Here, his unacknowledged and unpaid collaborators were the photographers, publicists, journalists, managers and studio bosses who had branded their human products as successfully as Campbell's had branded soups. Them, and Leonardo. Whatever the theorists say about these images as a commentary on or critique of (choose one or more of the following) reification, the admass, commodity fetishism, the simulacrum... a bright and honest child could tell you that they are nice, fun, pretty to look at because they were already nice, fun and pretty when Warhol first swiped them; and however "distanced" Warhol's Marilyn is from other, near-identical images, at least some of its pleasure remains the nigh- universal pleasure of the pin-up.

Norman Mailer once called Warhol "the most astute man in America": bluster, but well-founded bluster. Though Warhol would only let the Andy-the-Automaton mask slip very occasionally, when he was tired and in the company of the few people he trusted, it should have been obvious to all but the most naïve or drugged-out observer that inside the zombified village idiot was a bright, calculating and even dangerous man. (He once admitted how wearying it had been to play a cartoon character for 25 years.) His astuteness included not being too sophisticated to acknowledge some very elementary principles: fame breeds fame; give people what they already know they like, but with a little novelty; better to be derided than ignored, and so on.

Crucially, though, his astuteness could desert him, above all when it was a matter of being susceptible to the very mechanisms he exploited so profitably. None of the mud thrown at Warhol and his entourage – about the cruelty, the suicides, the exploitation, the harshness, the sleaze – stuck nearly so damagingly as that thrown by his old allies on the intellectual left when he began to court chic dictators, notably the Marcos family and the Shah, Empress and Princess of Iran – the latter a love affair cut short when the Ayatollah Khomeini made his triumphal entrance to Tehran in 1979, leaving Warhol with an unpaid bill of almost $100,000 for a set of royal portraits. Warhol's detractors called him and his gang "vermin", and declared that Warhol had been blinded by greed.

Well, he certainly liked his money, and at times had a peasant's closeness with it, though he could also be immensely generous with Christmas presents and the like. But what truly bewitched him about the Iranian royals was the same thing that bewitched him about, say, Nancy Reagan (profiled in possibly the single most grovelling and dim-witted piece that Interview ever ran): he thought they were chic, magical, glamorous. Glamour, for Warhol, was something very close to an absolute value, one that cancelled out every other consideration. And in this respect, if no other, the Warholian pose of superficiality was no pose at all: he was, so to speak, profoundly shallow.

Which would appear to bring us back to the present day, and the triumph of froth. There are fashions in perception as well as in clothes and hairstyle, and Warhol can be seen as an Yves Saint Laurent of sensibilities. Just as the wilder catwalk creations of fashion designers become adopted, adapted and diluted for high-street consumption, so the camp, avant-garde poses of Warhol and his mole people have become the cheaply purchased ironies of our own age. But it isn't the full story, or anything like it. One reason why Warhol has stayed interesting for more than 15 minutes is that his career is stuffed with knotty paradoxes, both calculated and unwitting. To focus on just one: yes, Warhol was indeed a snob, a social climber, a star-follower or worse. He was also, however, a weird kind of extreme democrat – "in the future, everyone will be worldfamous..." – and part of the original promise and thrill of Pop Art is that it put the traditionally aristocratic pursuits of dandyism and connoisseurship right out in the supermarket of mass culture, where anyone was free to join in. Whether we still want to join in is another question – a question on a par with "But is it art?" And Warhol, in heaven (he was a devout, if not a good Catholic), raises his quizzical eyebrow once again.

Warhol opens at Tate Modern, London SE1 on 7 February and runs to 1 April. Information: 020-7887 8000