Coming back from last night's Cafe Scientifique over in Tauranga, the speaker** & I were talking about the nature of science, and moved from there to the seemingly quite widespread acceptance of what could be called 'non-science'. One of the modalities that falls in the 'non-science' group, we agreed, is homeopathy. And this led us to wonder, why can you buy homeopathic 'remedies' in most pharmacies? Doesn't this sit a bit uncomfortably with the science-based training of the pharmacists?
The reason we asked this is because, whatever homeopathy is, it's not science-based. On one occasion, I had someone say to me, 'but, homeopathy has laws, just like science does.' Alas, they aren't the same thing. In science, a law (eg the gas laws) is a reliable explanation pr description of a phenomenon that will always show the same 'behaviour' in the same circumstances - no exceptions. This isn't the case for the 'laws' promulgated by the founder of homeopathy, Samuel Hahneman - these are more like statements of belief, in that they are not based on a body of evidence but rather, reflect Hahneman's ideas of how homeopathy worked.
Thus the the law of infinitesimalsstates that shaking a highly diluted homeopathic solution the correct way & required number of times will 'potentise' it,enhancing its healing power - but there is no evidence that this will happen. Similarly the idea of dilutions really doesn't stack up - a homeopathic 'remedy' labelled 30x will have been through a series of 30 one-in-one-hundred dilutions (where 1C = 1/100, 2C = 1/10,000, & so on). With such dilutions, the chances that a remedy actually contains any molecules at all of the active principle are vanishingly small. And while one researcher claimed to have found evidence that water somehow retains a memory of things that have been diluted in it, subsequent attempts to repeat this work proved fruitless. Just as well, really, when you consider all the things that water's had in it before it gets to the tap...
Why the dilutions? This stems from Hahneman's belief that a substance that causes similar symptoms to a disease, will also cure that disease (the idea of 'like cures like'). But, because in some cases these substances were themselves quite toxic (arsenic, for example), he hit upon the idea of diluting them to the point where the possibility of toxicity was inifinitesimal. Unfortunately, basic chemistry would also tell you that the possibility of benefit was equally small.
Yet people will tell you that homeopathy works. There are a number of possible reasons for this. One is that homeopathy's successes are due to the placebo effect, which is very real indeed. It's also the case that some 'homeopathic' treatments don't possess the usual high dilution number. Thus, in the US a popular cold remedy, Zicam, is described on its labelling as 'homeopathic' - yet it contained measurable amounts of zinc (2 parts per hundred). This turned out to be unfortunate, as at these concentrations zinc, when applied to nasal membranes, can destroy one's sense of smell. There's also the issue of regression to the mean, coupled with self-limiting conditions - many illnesses get better regardless of what you do.
You might ask why worry - if people get better using such treatments then surely it's OK? The reason I feel it's not OK is that from time to time you'll see claims that homeopathy can cure quite serious diseases - AIDS & malaria, for example. And if such claims lead to people neglecting to use therapies that do demonstrably work, then the consequences could be very serious indeed.
** BTW - the speaker was my colleague, the excellent Louis Schipper. He did a great talk on bioremediation treatment for nitrates in soil water (denitrification walls & denitrification beds) - & he's promised me first dibs for blogging on what sounds like a really exciting new research paper when it's published :-)