On 1 December, faith healers will meet at Roots & Shoots in south London to discuss how to treat Aids with magic pills. They won't call themselves faith healers, of course, or shamans or juju men. They will present themselves as 'homeopaths': serious men and women whose remedies are as good as conventional medicine.

According to the advance publicity, Hilary Fairclough, a homeopath endorsed by no less than Jeanette Winterson, will describe the 'impressive' results from her clinic in Botswana. Harry van der Zee, co-founder of the Amma Resonance Healing Foundation, will say that 'in just a few days or weeks' African Aids patients he treated became 'symptom-free and able to return to their jobs and schools or to look after their children again'. All in all, the Society of Homeopaths promises to provide 'fascinating insights' for World Aids Day.

It can do no such thing. Of all the pseudo-sciences on offer, homeopathy is the most obviously spurious. Devised by Samuel Hahnemann in the late 18th century, it holds that the smaller the dose of a mineral or herb the more potent it is. Thus, if you go into a chemist and buy a homeopathic sulphur remedy marked 30C, the proportion of sulphur to inert packaging in a pill is 1 to 100,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000. A glass of water is more likely to cure you.

Yet dismissing homeopathy as quackery given by and for the feeble-minded is surprisingly hard. Anti-elitism dominates our society and many feel uncomfortable saying that the six million people who take alternative medicines are foolish - to put the case against them at its kindest. They sincerely believe in phoney remedies and sincerity trumps sense in modern culture.

In rich and privileged societies where good health is taken for granted, homeopathy feels somehow natural when set against cold, conventional medicine. Today's audiences have no difficulty believing doctors and drugs companies are more villainous than their alternative rivals. Scrabbling around for a new plot after the end of the Cold War, John le Carre came up with The Constant Gardener, a story about drug manufacturers murdering Africans. 'Big pharmaceuticals are right up there with the arms dealers,' declares one character, who couldn't tell the difference between an antibiotic and a cluster bomb. Far from being dismissed as shallow, The Constant Gardener was a hit as a novel and a film.

You might have thought that the medical establishment would make a stand for science. After all, the reputations of the chief medical officer, Department of Health civil servants and doctors depend on their being able to say that they have tested their remedies in double-blind trials and understand why and how they work. But they happily go along with fake treatments that don't stand up to the most cursory scrutiny.

GPs use homeopaths as a dumping ground for hypochondriacs and the state pays for five homeopathic 'hospitals'. With the flood of money to the NHS about to be stemmed, Whitehall ought to close them and concentrate scarce resources on medicine that works.

However, any minister bold enough to argue for the effective use of public funds would face strong opposition. About 100 MPs signed a Commons motion asserting that homeopathic hospitals were 'valuable national assets' that could magic away conditions from eczema to irritable bowel syndrome. Well-known loons were joined by otherwise intelligent politicians who were content to have constituents conned.

Maybe they believed the standard justification for the homeopathy that the 'placebo effect' is a real psychological phenomenon. Patients suffering from minor ailments can feel better after taking a sugared pill. I've never liked the argument because there would be no placebo effect if patients were told the truth. To endorse homeopathy on the NHS is to endorse state deception. In his forthcoming Counterknowledge, Damian Thompson of the Daily Telegraph goes further and makes a persuasive case that what we tend to dismiss as harmless fads for Cherie Blair and her kind cause immense suffering in the wider world.

The NHS's backing for public homeopathic hospitals legitimises private homeopaths. An investigation by Newsnight showed 10 of them putting patients' lives in danger by rejecting anti-malarial drugs for pills containing infinitesimal quantities of garlic and citronella oil. But you have to turn to the Africa le Carre couldn't see to understand how the bugbears of people we think of as eccentrics can turn lethal.

For years, South African President Thabo Mbeki has done his best to hinder the distribution of anti-retroviral drugs. He listens to Peter Duesberg, a biologist who argues that to prevent Aids, all you need to do is eat well and avoid recreational drugs. After hearing Duesberg speak at a conference, Anthony Fauci, the usually mild-mannered Aids adviser to the American administration, said: 'This is murder. It's really that simple.'

It's not just Duesberg. Bogus nutritionists in Britain and Germany claim vitamin C is as effective a treatment for Aids as anti-retrovirals and, as we have seen, homeopaths are claiming Africans can walk out of their clinics 'symptom-free'. Don't think that just because they seem obscure cranks their ideas can't have influence when the net makes them available to anyone anxious to deny the established facts about Aids.

Suppose the old regime hadn't fallen and a white minority government was indulging Aids denialists. I think it's fair to guess the streets of the world's capitals would be full of demonstrators accusing the apartheid government of being complicit in the mass killing of blacks.

Terms such as 'genocide' and 'ethnic cleansing' would be tossed about and those who provided spurious arguments to justify the neglect of South Africa's Aids' victims would be denounced as the accomplices of a criminal policy.

As it is, there are no demonstrations because it is a black government presiding over the disaster and its supporters aren't in big pharmaceutical companies but funny little alternative institutes we too causally dismiss as quaint.