Patients who take a placebo - literally "I shall please", which makes it sound like the kind of promise you may find on a dubious card in a Soho phone kiosk - regularly find that their symptoms clear up, because of the mere thought that they have received some medication.
In that respect, illness really can be shown to be in the mind. Only if the drug is demonstrably more beneficial than the harmless placebo is the drug marketed.
In such circumstances, the advantages of a double-blind trial - where nobody knows whether Mr Smith or Ms Brown is swallowing a real or a virtual pill - are obvious, and there is no downside.
The latest example of placebos is, however, different. The use of placebo surgery for testing a treatment for Parkinson's disease means that choices become more complex. Participants in the trial have a 50 per cent chance of receiving the transplant of foetal tissue that is reckoned to help Parkinson's sufferers. But those who do not receive the foetal tissue are still operated on, with all the accompanying dangers of having a hole drilled in their skulls.
Ignorance is not at issue, as far as the patients are concerned. Unlike the situation in past years, when doctors cheerfully gathered medical evidence without telling their patients, those who take part in the trial are aware of the potential risks that they are running. In that sense, we have moved away from the idea of the doctor as God.
That, at least, is progress. Once upon a time, doctors scarcely concerned themselves with ethical issues. (The British Medical Association's first handbook of medical ethics was published only 20 years ago.) Now, ethics are at the forefront of medical concerns, on everything from fertile old ladies to cloned sheep. But the choices don't get easier. How many cured Parkinson's patients justify one botched hole in the head? It is not surprising that ethicists sometimes sound confused.Reuse content