Fahrenheit 9/11 is a work of propaganda. Like all such work, it radiates contempt for its audience. Michael Moore addresses his viewers not as citizens seeking to deliberate on the state of the American republic, but as dogs to be trained in a Pavlovian manner.

Propaganda is always polemical, but not all polemics are propaganda. Fahrenheit 9/11 qualifies not because it is one-sided but because it subordinates truth to politics. The genre of polemic neither requires nor excuses that subordination; yet such subordination defines Moore's film.

There is little point offering a catalogue of Moore's deceits here. Many such lists are already available and a simple list of errors cannot capture the full extent of Moore's perfidy. Since Moore's film relies largely on innuendo and association – techniques well suited to propaganda – there are few factual errors within the film for one simple reason: there are not many explicit factual claims.

Yet, in almost every frame, Moore invites the viewer to draw conclusions that he knows perfectly well to be false. Fahrenheit 9/11 is, in short, an utterly unscrupulous work. After watching it, I left the cinema convinced that Moore would have laced his film with subliminal images of Bush smashing a child's skull against a rock if he had thought he could get away with it.

Moore organises his material around a series of conspiracy theories designed to prove his central thesis that George W. Bush is an idiot-demon that, through his avarice and stupidity, is a threat not just to American democracy but also to the whole world.

Even judged as conspiracy theories, Moore's mini-essays are third-rate. A robust conspiracy theory must form a tight circle, insulating the theorist from contradiction, but Moore never manages to close the loop. As soon as he finishes trying to persuade us that the Saudis have shadowy financial ties to the Bush family – he offers a figure of $1.4 billion which has been given, in his slippery formula, to "the Bush family, their friends and their related businesses" – he moves on to the invasions of Afghanistan and Iraq, both of which the Saudis opposed.

That is not to say that Moore is not close to a real problem, but his monomaniacal approach prevents him from seeing it. The Saudis, as many of the more serious commentators from across the political spectrum have said for some time, do enjoy an unhealthy amount of influence in Washington. Moore shows the Saudi ambassador, Prince Bandar, getting on rather too well with the current president, but matters are worse that he suspects or cares to discover.

The truth is that Bandar has been getting on rather too well with a succession of US presidents, both Democrat and Republican, ever since his appointment in 1983. And, while each administration comes and goes, Bandar remains a permanent fixture of American politics.

By contrast, US ambassadors to Saudi Arabia are always non-Arabic speakers and are all but handpicked by the Saudi royal family. Rotated on a frequent basis, when these diplomats return to the US, they do so secure in the knowledge that the Saudi government has a long history of taking care of ex-ambassadors' needs. This arrangement can inevitably lead to an extraordinary amount of corruption.

But Moore is not interested in this, or any other problem that cannot be pinned on the Bush administration. He talks about the policies of previous administrations, but only in order to discredit the current one. He never tires of pointing out that the United States once supported Saddam, as if this proved the moral case for deposing him was invalid. But, as Christopher Hitchens has consistently argued, if this history had any relevance to the debate at all, it weighed in favour of invasion. The United States had a duty to remove the monster it helped to create.

Oil is the film's leitmotif, the common theme that recurs in his treatment of Saudi Arabia, Afghanistan and Iraq. In the debate over the invasion of Iraq, the mantra "It's all about the oil" was always a premise posing as a conclusion, but few have exemplified the naivety of this cynicism as effectively as Moore. In a recent interview with the Los Angeles Times, he voiced what must be considered the reductio ad absurdum of the 'All About The Oil' position. To argue, as he did, that "the support Bush and the Republicans feign for Israel is because Israel is near our oil" is not just ignorant, it represents a sort of anti-knowledge.

Perhaps the most shocking material in the film shows US troops abusing Iraqi prisoners. Such abuse is as inexcusable as it is obscene, although nothing Moore shows us is quite as horrific as the photos taken in the Abu Ghraib prison. When the Abu Ghraib story broke, the question on everyone's lips was "Who knew what and when did they know it?"

Well, shortly before the release of Fahrenheit 9/11, Moore boasted that he had footage of US troops abusing Iraqis months before the Abu Ghraib story broke on 60 Minutes, the weekly CBS news show. By his own admission, Moore knew about the abuse of Iraqi prisoners. He had proof, but kept silent.

When challenged about this decision, Moore said: "I wanted to come out with it sooner, but I thought I'd be accused of just putting this out for publicity for my movie." It would be hard to imagine a more craven justification. Moore's public statements are not to be trusted, but the fact that he even thought this was an adequate response reveals how far out of his depth he is. The decent thing would have been to release the footage; suspicions over his motives be damned. The American people would have seen what Moore evidently could not: here was a story bigger than him.

Fahrenheit 9/11 reaches its moral nadir with a brief montage depicting Iraqi life prior to the invasion. In this sequence, the audience sees, in quick succession, a boy dancing, a cheerful wedding and a variety of images of children playing, smiling and flying kites. The footage is genuine, but Moore's collage is a cinematic Potemkin village.

In the Iraqi province of Kirkuk, US forces discovered a mass grave especially for children. No doubt before Hussein's regime consigned them to that grave, those children spent time playing and even flying kites, just as the adults that fell victim to Hussein's tyranny no doubt smiled at their weddings. To show only the playground, and not the grave, is dishonest. A man that chooses to depict pre-war Iraq in this way shows himself to be incapable of shame.

As the film moves towards its conclusion, Moore quotes George Orwell's Nineteen Eighty-Four – or, more accurately, he presents a paraphrase as if it were a quotation. Orwell's words are cogent, but when you hear them coming from Moore's lips, at the end of a film in which he portrays a totalitarian regime as if it were an attractive holiday destination, the effect is surreal. In his celebrated essay "Why I Write", Orwell identified his salient gift as "a power of facing unpleasant facts". It is a cruel irony that 101 years after his birth, Orwell's words have been appropriated by Michael Moore, a trafficker in convenient fictions.

Many commentators frequently compare Michael Moore to Rush Limbaugh, the splenetic right-wing talk radio host – the comparison works better in the US since Limbaugh, unlike Moore, is not a successful export. There is some truth in the comparison, but there are also significant asymmetries, not least in the way that the political establishment has welcomed Moore. Since the release of Fahrenheit 9/11, prominent Democratic congressmen have fawned over the filmmaker; he even received a place of honour at the recent Democratic National Convention.

The sudden respectability of Moore's type of propaganda seems puzzling. Yet, in context, it is the logical consequence of the rhetorical inflation that has gripped America since the 2000 Presidential Election.

Not content to call Bush a bad president that deserves to be voted out of office, Bush's opponents have repeatedly labelled him a fanatic bent on turning America into a police state. This rhetoric of crisis makes it easy to justify the suspension of all normal standards of political discourse. The result is the principled hypocrisy adopted by the likes of Paul Krugman, the Princeton economist and New York Times columnist, who argued that, while there were parts of Moore's work that deserved criticism, the criticism should wait until "the crisis of American democracy is over".

There has been much speculation about whether Moore's film will have an impact on the forthcoming 2004 Presidential Election. If it does, then I suspect that its net effect will be in Bush's favour. Moore's primary constituency consists of those already signed up to the anti-Bush cause, but he will gain some converts amongst independent and undecided voters.

However, the impact of these converts will be more than offset by Moore's impact on the large amount of Americans who have no love for George Bush, but feel disturbed by the increasingly unhinged character of the Anyone But Bush crowd. A great many Americans do not belong to Bush's base, but they may prefer to see Bush win a second term, rather than vote for a man that has yet to articulate a credible case for his election to America's highest office. It is these Americans that will be decisive in the next election and, if they see Fahrenheit 9/11, they may conclude that if the case against Bush was really as strong as many people seem to think, then Moore would not have needed to rely so heavily on cheap shots and innuendo.

But to end with predictions would be careless, as judging propaganda by its effectiveness concedes too much to the propagandist. No one should approach his fellow citizens as Pavlov approached his dog. We should reject Moore's film not because it will fail in its goals, but because it rides roughshod over truth.