What makes it an event is the fact that it is an effective and independent intervention into immediate world politics. Today it is rare for an artist to succeed in making such an intervention, and in interrupting the prepared, prevaricating statements of politicians. Its immediate aim is to make it less likely that President Bush will be re-elected next November.

To denigrate this as propaganda is either naive or perverse, forgetting (deliberately?) what the last century taught us. Propaganda requires a permanent network of communication so that it can systematically stifle reflection with emotive or utopian slogans. Its pace is usually fast. Propaganda invariably serves the long-term interests of some elite.

This single maverick movie is often reflectively slow and is not afraid of silence. It appeals to people to think for themselves and make connections. And it identifies with, and pleads for, those who are normally unlistened to. Making a strong case is not the same thing as saturating with propaganda. Fox TV does the latter; Michael Moore the former.

Ever since the Greek tragedies, artists have, from time to time, asked themselves how they might influence ongoing political events. It’s a tricky question because two very different types of power are involved. Many theories of aesthetics and ethics revolve round this question. For those living under political tyrannies, art has frequently been a form of hidden resistance, and tyrants habitually look for ways to control art. All this, however, is in general terms and over a large terrain. Fahrenheit 9/11 is something different. It has succeeded in intervening in a political program on the program’s own ground.

For this to happen a convergence of factors were needed. The Cannes award and the misjudged attempt to prevent the film being distributed played a significant part in creating the event.

To point this out in no way implies that the film as such doesn’t deserve the attention it is receiving. It’s simply to remind ourselves that within the realm of the mass media, a breakthrough (a smashing down of the daily wall of lies and half-truths) is bound to be rare. And it is this rarity which has made the film exemplary. It is setting an example to millions - as if they’d been waiting for it.

The film proposes that the White House and Pentagon were taken over in the first year of the millennium by a gang of thugs so that US power should henceforth serve the global interests of the corporations: a stark scenario which is closer to the truth than most nuanced editorials. Yet more important than the scenario is the way the movie speaks out. It demonstrates that - despite all the manipulative power of communications experts, lying presidential speeches and vapid press conferences - a single independent voice, pointing out certain home truths which countless Americans are already discovering for themselves, can break through the conspiracy of silence, the atmosphere of fear and the solitude of feeling politically impotent.

It’s a movie that speaks of obstinate faraway desires in a period of disillusion. A movie that tells jokes while the band plays the apocalypse. A movie in which millions of Americans recognize themselves and the precise ways in which they are being cheated. A movie about surprises, mostly bad but some good, being discussed together. Fahrenheit 9/11 reminds the spectator that when courage is shared one can fight against the odds.

In more than a thousand cinemas across the country, Michael Moore becomes with this film a people’s tribune. And what do we see? Bush is visibly a political cretin, as ignorant of the world as he is indifferent to it; while the tribune, informed by popular experience, acquires political credibility, not as a politician himself, but as the voice of the anger of a multitude and its will to resist.

There is something else which is astounding. The aim of Fahrenheit 9/11 is to stop Bush fixing the next election as he fixed the last. Its focus is on the totally unjustified war in Iraq. Yet its conclusion is larger than either of these issues. It declares that a political economy which creates colossally increasing wealth surrounded by disastrously increasing poverty, needs - in order to survive - a continual war with some invented foreign enemy to maintain its own internal order and security. It requires ceaseless war.

Thus, 15 years after the fall of communism, a decade after the declared end of history, one of the main theses of Marx’s interpretation of history again becomes a debating point and a possible explanation of the catastrophes being lived.

It is always the poor who make the most sacrifices, Fahrenheit 9/11 announces quietly during its last minutes. For how much longer?

There is no future for any civilization anywhere in the world today which ignores this question. And this is why the film was made and became what it became. It’s a film that deeply wants America to survive.

John Berger is a novelist and critic