Anti-Iraq allies propaganda has, to date, failed at almost every point

“Horse chestnut for haemorrhoids. Oh, yes!”

I've walked in on many a conversation in my time, but rarely happened on a comment delivered with such orgasmic enthusiasm. Lurking behind the rice cakes in the health food store, I could still hear the cashier holding forth, without my obvious interest adding to the pressure on the customer with the putative piles.

The customer sidestepped the recommended remedy and asked where the usual manager was, presumably because when the regular guy advised her on her ailments, he didn't broadcast problem and possible solution all over the shop like a human Tannoy no matter what his sympathy for the former or faith in the latter.

"Oh, Dave is gone to the peace demonstration in Washington," the cashier warbled, offering a leaflet about preventing war in the Gulf. The woman politely rejected the leaflet as well as the horse chestnut before returning to a town car roughly the size of Lusk.

It never seemed to strike the peace-loving cashier that her shiny-eyed approach had not influenced the departing customer. The incident resurfaced in my mind when interviewers started asking people if they'd been convinced by Colin Powell's presentation to the UN.

What a daft question. Like asking someone if they've found horse chestnut useful for their haemorrhoids before you've found out if they've ever had either. The notion is naive at best that anywhere in the world vast numbers of people exist in so open-minded and uninformed a condition that all it would take to convince them of the need for war is a firm jaw, eloquent oratory and mighty visuals. All of which Powell had. None of which de-convinced those already convinced the other way.

Pre-existing prejudices are what matter. If interviewers first asked their guests "where were you on possible war in Iraq before Powell started his presentation?" they'd have been able to guess with fair accuracy where the interviewees would be after he finished. Television is a polarising rather than enlightening medium. It pushes people further into the corner they're already in. Viewers select the evidence to justify the stance they've already taken.

You can try this at home, any evening, although last week had a couple of particularly vivid examples, not least the Bashir Reality TV visit to Michael Jackson. Those viewers who, prior to the programme, believed Jackson to be a crackpot with a semi-detached face, a real and present danger to children his own included were pretty damn sure after the programme they had been right all along.

Contrary to that, viewers who, pre-Bashir, had viewed Jackson as a harmless child-like genius victim of an abusive father ended up sympathetic to him and a bit teed off with the interviewer. (Those of us in the communications business ended up convinced that anybody who takes PR advice from Uri Geller needs his spoons examined, and is it any wonder he can't find his own child's mouth when he wants to stick the bottle in it?)

Powell's behaviour, prior to the UN presentation, argues that he was happily content with the limitations of his own persuasiveness and was simply in the business of confirming the already convinced. So he was all happy-clappy until it was time to get serious and start the pictures rolling. A curious disjunction, this.

No actor who wants to enmesh the audience in the misery of a betrayed old fool would first come out on stage joshing with the other actors for a few minutes before lowering a damper on his jollity and turning into King Lear.

Cassandra, if we believe contemporary accounts, didn't rollick around in the morning like an early Cilla Black and then, at lunchtime, go: "But seriously, lads, yiz face a bit of Armageddon, here."

Powell's face-straightening when it came to the presentation was peculiar, but it wasn't the worst thing. The worst thing was the fact that he used PowerPoint.

Every now and then, in the day job, I watch some Armani'd executive doing a presentation, their PowerPoint-dependence so total that if their computer breaks down, their thought processes do likewise. They've been so trained by PowerPoint that they simply can't think sequentially any more, so, without the click to flip up the next screen full of clues, they're lost.

Powell's use of PowerPoint is the quintessential (and, hopefully, final) demonstration of how ineffective it is as a communications tool, no matter how technically impressive it may be, when set against one impassioned storyteller who can cause listeners to imagine an unseen picture.

That's what happened in the run-up to the last Gulf War. The moral righteousness of the fight against Iraq was frequently justified by reference to an incident where Iraqi soldiers tossed premature babies out of incubators in a hospital in Kuwait in order to dismantle the machines and take them back home.

One young woman, apparently an eye witness, described the incident to the TV cameras with such patent revulsion that without ever seeing the dead premature babies the world shuddered.

Much later, it emerged that the storyteller was the daughter of a member of the Kuwaiti royal family, and that the story itself wasn't true, it never happened. But what is frightening is that, even though it didn't happen, the facts did not count against the perceived authenticity of the speaker.

"The veracity of her story was indelibly marked on my mind when I saw her," was the response of an executive of Hill&Knowlton, the lobbying and public relations company involved in publicising the incubator propaganda when it was pointed out that the whole thing was fake.

In other words, this lying woman must still be believed because she told her (untrue) story so well. In the heightened pace and emotional temperature of impending war, nonsense can be accepted as fact if the constituent sections of it cohere to form a powerful, coherent, action-justifying narrative.

This time, no 'incubator incident' has been adduced to persuade non-Americans and non-Britons to support Gulf War II. The propaganda of the anti-Iraq allies has, to date, failed at almost every point.

Tony Blair's killer dossier turns out to owe more than is credible to the diligent homework of a Californian student. A reporter investigating Powell's claimed 'terrorist chemicals and poisons factory' not only finds the 'factory' to be a shabby military compound at the bottom of a mountain, but is asked the sensible question by the local head honcho: "Since we don't have aspirins for our fighters, how could we produce chemical weapons of mass destruction?"

Of course, the pleasure of deriding the ineptitude of attempts to persuade is somewhat tempered by the realisation that it may derive from disregard of the audience.

Or, to put it more bluntly, those whose views don't matter don't have to be convinced.