In 1954 and 1955 a professor of English at Oxford University published a long, rambling fairy story in three hardbacks. And nothing much happened. This was the 1905 of fantastic literature - a dress rehearsal for the revolution. That revolution came in earnest ten years later, when the book, The Lord of the Rings, was published in the US in cheap, pirate paperbacks, along with rapid response authorised versions. And they sold. A generation of students, hippies and potheads found hidden meanings in legends of power, wisdom, magic and secret knowledge. They reconfigured the texts, and turned a quaint, portentous 1950s fable into a key counter-culture text of the 1960s - to the avuncular professor Tolkien's bemused horror.

John Ronald Reuel Tolkien belonged in the rarefied air of Oxbridge, from where he wrote scholarly works, smoked his pipe and constructed his imaginary world, Middle Earth. It would be hard to imagine a man less at home among his new readers, whom he called the 'lunatic fringe'.

The influence of The Lord of the Rings on modern literature and culture has been enormous and controversial. Its iconography is everywhere, constantly stolen and ripped off. But when it topped a recent poll as 'book of the century', many highbrow types were appalled that such a 'childish' work of fantasy was so honoured. The literary establishment's incoherent critique combines snobbish disdain for popular culture with an ahistorical philistinism. It sees the fantastic as pathological, as sub-literary, rather than as one mode of expression among many. Those of us who skulk by those garish shelves in the bookshop have all been told that we'll grow out of it, or asked when we're going to start reading real books. And there is a left variant of this dismissal, which follows the Marxist critic Lukács in seeing the fantastic as decadent or socially 'irresponsible'. But if, as radical critics of both bourgeois respectability and Stalinist agitprop, we defend science fiction and fantasy, does that mean we should be rallying under the banner of 'Socialists for Tolkien'? Hardly.

Politics and aesthetics

Tolkien was no political ally. He was a devout Catholic who moaned incessantly about the modern world - not capitalism, not exploitation, but modernity itself, which he saw as the triumph of a sinister 'Machine'. His was a profoundly backward-looking reaction, based on a rural idyll that never existed - feudalism lite. As socialists, we don't judge art by the politics of its creator - Trotsky loved Céline, Marx loved Balzac, and neither author was exactly a lefty. However, when the intersection of politics and aesthetics actually stunts the art, it's no red herring to play the politics card.

Along with CS Lewis, author of the Narnia books, Tolkien was one of the 'Inklings', a group of Christian writers who met to discuss religion, history and fantasy. It's impossible to generalise about their work. In one corner was Lewis himself, whose brand of rugger playing, misogynist Anglicanism is expressed in his constant sneering at his own characters - especially the girls - over their own heads. He implicates the reader in something akin to school bullying. Opposite him was the much more obscure Charles Williams, whose occultist Christianity gives his fascinating works great mystery and power. They are confused, but deeply impressive and affecting. Tolkien is much closer to Lewis than Williams, though markedly less snide and unpleasant. He deliberately tried to sound antique and 'epic'. Cliches constantly snuffle up to us like moronic dogs. Laughter comes in 'torrents', brooks 'babble', and swords never fail to 'flash'. The dialogue sounds faintly ridiculous, like opera without the music. Even 50 years ago this cod Wagnerian pomposity was stilted and clumsy. 'Fey he seemed,' says JRR - in Middle Earth, rare the clause is that reversed isn't.

The linguistic cliches are matched by thematic ones. The stories are structured by moralist, abstract logic, rather than being grounded and organic. Tolkien wrote the seminal text for fantasy where morality is absolute, and political complexities conveniently evaporate. Battles are glorious and death is noble. The good look the part, and the evil are ugly. Elves are natural aristos, hobbits are the salt of the earth, and - in a fairyland version of genetic determinism - orcs are shits by birth. This is a conservative hymn to order and reason - to the status quo.

The hobbits' 'Shire' resembles a small town in the Home Counties, full of forelock-tugging peasants and happy artisans. Though he idealises the rural petty bourgeoisie, Tolkien treats them with enormous condescension. 'It would be a grievous blow', he says, if the Dark Power were to claim the Shire - to translate, if rural workers were industrialised. Because the good professor loves them so, with their hand-mills and their funny little rural ways. Not that he would want to be one, of course - good lord, no. He has a PhD, don't you know.

The Lord of the Rings is by a large margin the most influential fantasy book ever, and has created an entire sub-genre of 'high' fantasy - 'sword and sorcery' epics of dragon-slaying warriors and beautiful maidens. A lot of it is dreadful, some of it is very good. Though much of this influence is down to the book's appearance at just the right time, it would be churlish to claim that there's nothing to admire in the book. The constant atmosphere of melancholy is intriguing. There are superb, genuinely frightening monsters, and set pieces of real power.

But Tolkien's most important contribution by far, and what is at the heart of the real revolution he effected in literature, was his construction of a systematic secondary world. There had been plenty of invented worlds in fantasy before, but they were vague and ad hoc, defined moment to moment by the needs of the story. Tolkien reversed that. He started with the world, plotted it obsessively, delineating its history, geography and mythology before writing the stories. He introduced an extraordinary element of rigour to the genre.

This type of project is often mocked by those critical of fantasy. However, it allows for a unique and - at least potentially - uniquely engaged kind of reading. Readers can inhabit these worlds, and become collaborators in the process of constantly creating them, suspending their disbelief. For this we owe Tolkien a sincere debt. For all of us interested in the fantastic, however critical we are of him, Tolkien is the Big Oedipal Daddy.

But ultimately it's not the size, shape or rigour of your secondary world which is most important - it's what you do with it that counts. Tolkien claimed the function of his fantasy was 'consolation'. In other words, it becomes a point of principle that his literature mollycoddles its readers. Tolkien and his admirers (many of them leftists) gave his escapism an emancipatory gloss, claiming that jailers hate escapism. As the great anarchist fantasist Michael Moorcock has pointed out, this is precisely untrue. Jailers love escapism. What they hate is escape.

Tolkien is naive to think he's escaping anything. He established a form full of possibilities and ripe for experimentation, but used it to present trite, nostalgic daydreams. The myth of an idyllic past is not oppositional to capitalism, but consolation for it. Troubled by the world? Close your eyes and think of Middle Earth.

Fantasy geek delivers our just desserts

What happens when a New Zealand film and fantasy geek meets Tolkien's ponderous epic? Something pretty damn good. Peter Jackson, the director, is best known for his 1994 Heavenly Creatures, a disturbing true murder story. But he earned his place in history by making the best sort of schlock, like the world's greatest slapstick zombie comedy horror, BrainDead. The fact that someone so out of the Hollywood-blockbuster loop was given the opportunity to direct The Lord of the Rings has raised eyebrows and expectations. Tolkienistas will be swapping outrage at Jackson's changes to the sacred text. These alterations are in fact almost all - whisper it - improvements. Jackson beefs up Tolkien's rizla-thin women, turning them into actual characters. He takes mercy on us and cuts out the sing-songs, and the tooth-achingly awful character Tom Bombadil, a cod-folk nature spirit whose soliloquies sound like the ramblings of a village idiot. So far, more power to Jackson's scissors.

But not all his interventions are so successful. He gives the film a peculiar pace, by starting with an intense and frenetic backstory. While visually stunning, this passage means that we lurch into the film at a hell of a pace and don't slow down. The book, by contrast, is structured by a sense of growing foreboding, the film's loss of which is a shame. This is, however, a function of one of Jackson's most laudable qualities. He finds it essential to give us all the background because of the absolute seriousness with which he treats the material.

The Guardian review of the film managed completely to miss this point, complaining about the 'leap of faith' necessary to inhabit the film's universe and sneering at actors 'deadpanning' lines about orcs and elves. This is precisely the film's strength. The actors are not 'deadpanning' but acting, immersing themselves in Tolkien's world. Jackson is admirably out of step with the Hollywood mainstream, in which directors wink at and nudge their audience tediously, undercutting passion with heavy-handed 'referentiality' and in-jokes. This is the postmodernism of philistines, and Jackson disdains it. Instead he cares passionately, even about something as flawed as Tolkien's work, and commits to it totally. The film is rich with this integrity.

Of course there are problems. Elijah Wood (Frodo) hasn't quite the presence needed for his part. Cate Blanchett plays the elf Galadriel like a cosmic Princess Di. But most of the acting is good. Some, especially that of Ian McKellen (Gandalf) and Sean Bean (Boromir), is excellent. The set pieces and special effects are superb, again because of Jackson's unusual approach. Computers are a means to an end, not the end itself, and they are used more sparingly than is fashionable - to much better effect. This is best illustrated in the battle sequence in the mines of Moria, an outstanding section.

And after years of fantasy films which were little more than jokes, I watched The Lord of the Rings with something like gratitude - a feeling that finally we have what we deserve. The film is a passionate love affair between Jackson and the book. And, like all true love, it's genuinely moving to watch, even if you're not over-fond of one of the lovers.