The problems with clinical trials of CAM: a case of wholly holey socks?

A lot of hot air has been expended on homeopathy’s apparent inability to “prove” itself in clinical trials. Many people, many of whom call themselves scientists, seem only to need this fact, plus the therapy’s apparent implausibility, to jump to the conclusion the whole thing is nonsense on stilts, and work themselves up into lathers of righteous indignation about the fact that it continues to be practiced. I’ve gone into this a couple of times in the comments to posts on this blog, but this question really does deserve detailed examination, because the issue is not at all as simple as it might seem.

The presupposition of clinical trials is that there is a stable, locally active cause that is only active in the treatment group, irrespective of blinding and the circumstances of the trial or any changed clinical context as a result of the trial. In plain English, this means that the whole basis of clinical trials is predicated on the assumption that the bulk of the treatment effect resides in the physical substance that’s being trialed. It’s a localist hypothesis, proceeding — in homeopathy’s case — from the following logic: