I recently co-authored a letter to the Irish Times in response to a letter from homeopath Sheelagh Behan, in which she offered a defence of homeopathy following an earlier anti-alternative medicine article by Paul O'Donoghue (founding member of the Irish Skeptics Society). The letter wasn't published and so I have posted it here instead.
Sheelagh Behan's defense of homeopathy (letters, 17th September) uses some fairly common strategies employed by homeopaths to bolster their art, but she fails to actually provide any compelling reasons to endorse the prescription of water for medical conditions more serious than dehydration. Her arguments can be summed up as a combination of the fallacies; i) appeal to the people, ii) appeal to authority, and iii) pseudo-scientific language.
i) Yes homeopathy is widely used; so were leeches, but no matter how many people used them they were never more effective than a placebo. Science is not a democracy - it relies on reproducible experimental evidence.
ii) Regarding the two studies actually mentioned; the first, a study of E. coli in Dutch piglets was published in a journal entitled "Homeopathy", an outlet unlikely to critically examine homeopathic hypotheses. The second, namely Luc Montagnier's study of electromagnetic signals from DNA in water did not even directly test the power of dilution but instead attributed an effect to dilution following a *filtration step*. Indeed, unfiltered bacteria gave no signal at all when diluted, in direct contrast to the central tenet of homeopathy. Also, the electromagnetic signals reported following filtration were mostly unaffected by dilution rather than enhanced by it, and the authors make no claim to have shown a mechanism for homeopathic efficacy. All in all, their results might be true, but using Occam's razor one would first need to rule out simpler explanations, such as the filtration process introducing a contaminant that may emit the signal. (Edit: see here for a thorough rebuttal of Montagnier's study)
iii) Lastly, hormesis, the belief that a little poison is good for you, is neither widely accepted in toxicology nor does it validate homeopathy's second principle of so called "potentization". It is closer to Murphy's law (which isn't a law) or the 80-20 rule (which isn't a rule) than to any scientific law and it does nothing to prove there is any trace (or memory) of the original "remedy" left after so many dilutions. If there are such traces (or memories), then patients would also receive the effects of whatever else the water has previously diluted.
While people in any free society should have the right to seek whatever treatment they prefer, they should be completely informed as to what they might be paying for, whether directly or through health insurance premiums. Homeopathy makes claims that its treatments are more effective than a placebo and, therefore, does not reliably inform patients and the public.
As Dara O'Briain says, when alternative medicine works, it simply becomes *medicine*...