Simon Carr: Why knock something that gives us comfort?

In defence of the ridiculous. Now mediums – even the "genuine mediums" provided for in the previous Act of Parliament – have to put up a sign saying they're only entertainers. "This séance is for entertainment purposes only" they are expected to say. The same goes for palm readers, psychics, healers, chakra-massagers, and possibly for all sorts of complementary medicinal activities.

Some years ago I went to interview a newspaper astrologer. He must be a multi-millionaire now, with his premium-rate phone lines. We chatted for a little, I brought up Popper's test of falsifiability and expressed skepticism about his work. He glared at me, pulled out his book of numbers, scanned the column for my birthday, and found an afflicted Saturn. "You suffered some trauma when you were very young which has affected your whole life," he said.

I had to sit down. He'd winded me. I couldn't falsify his proposition but it's stayed with me ever since. I don't know if that's a good thing or bad, but it's impressive. He put a sort of memento mori into the back of my head, like an implant. Sometimes I cast back wondering what my trauma might have been, if anything. I brood over my life, the disasters mainly, and wonder how I can get through the next disaster (they're usually the same) more efficiently. The lesson, I suppose, is don't insult an astrologer.

Of course horoscopes aren't true, like gravity is true, or bacon. It's a prose style. Open Linda Goodman's Love Signs and you will find your own love life laid out in black and white. The very arguments you have with your spouse are there word for word. And it doesn't matter which page you open it at, or which sign you are. Astrology isn't a science or even an art, but at best it's a sort of therapy. What we can see of it is a prose style.

"While you have a sense of humour and are at bottom a decent person, you are not always appreciated by your family or work colleagues," writes Goodman. This provides a therapeutic opportunity for people to look at themselves. And goodness knows, I've had some therapy sessions as pointless as a Tarot reading. Madame Sostris could have done a better job than those qualified men the lawyers won't allow me to name.

But who knows where the line is and when we cross from the respectable to the ridiculous. Only a third of medicines work as they should, we are told. A British Medical Journal editorial recently had it that codeine was no more effective than a placebo in 60 per cent of cases. And when the subjects were told the placebo was ten times more expensive than usual, the effectiveness went up to 85 per cent. Crucially, the placebo effect was fortified by the patient spending three quarters of an hour with the doctor before taking the tablet.

This little nugget of information about the way we humans are, incidentally, overturns the basis of how to run GP services in Britain. Spending time with the shaman, or Dr Dolittle, is a crucial part of the remedy. I don't think we want a sign saying "for entertainment purposes only" above our GP's desk, do we? The belief, or faith, turns out to be a crucial part of the therapy.

Because how does your body heal? You take drugs that kill the invaders. Or you stimulate the immune system to do the same job. There's such a large mystery in that second way that mainstream science rather runs round it.

Faith healing works, sometimes, for those with faith. Conversely, witch doctors can kill susceptible people with a pointed bone. Homeopathy has no basis in science and yet it cures people whose temperament is suited to it. It calls up their latent energies, perhaps. Acupuncture has no biochemical foundation and we all remember the early Jonathan Miller precisely aware of his foot being pricked; and yet acupuncture has been used as an anaesthetic for heart surgery.

Would we want a disclaimer saying "for entertainment purposes only" at the start of an exorcism? Aha, you say, I've defeated my own argument, of course we would, and who could fail to be drawn to the spectacle? But what about those ecstatic healing sessions with snakes? Whatever's going on, there is some sort of special communion that most of us can't penetrate, and at which we don't belong.

But let's be realistic. The public clearly needs protection against unscrupulous fraudsters. We are all vulnerable to powerful and persuasive conmen who are after our money. Remember Westminster spends £600bn of our money every year. So maybe we should demand an "only for entertainment" disclaimer at the end of modern legislation? The laws, that is, that are written to "send a message" (that is, most of them).

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