Response: potential nonlocal mechanisms make placebo controls in pathogenetic trials difficult

Sherr and Quirk have a point: the pathogenetic trials included in the review paper they criticise have been judged against the standard criterion such as whether they used placebo control, and used this control properly, ie in a double blind manner.[ ¹ ] From a conventional point of view this argument is correct.

However, since this review was designed, new ideas and data have emerged. These suggest that perhaps a nonlocal model should be applied to homeopathy as a whole.[ ^2–4 ] If such nonlocal models are validated it might be doubtful whether blinded placebo controls actually act as an adequate filter for noise, as specific symptoms have to be expected in those groups as well. We have seen such effects in more recent homeopathic pathogenetic trials[ ^5,6 ] and this has raised doubts as to whether placebo controls can actually control properly for what they are supposed to control within homeopathic pathogenetic trials.

It is a well-known lore of homeopathic proving that those in control groups, relatives, or even the pet dog may develop proving symptoms although they have not taken the remedy. This lore, although anecdotal and not scientific evidence at all, is valuable since it suggests that placebo controls might not be adequate. However, until this potential conundrum is more clearly elucidated and scientifically accepted by a majority of researchers in the field we will have to live with the fact that double blind placebo controls will be held as the standard against which homeopathy is going to be judged. In full knowledge that this might actually dilute homeopathic effects due to potential nonlocal mechanisms this is indeed a difficult situation to find oneself in. Hence, some of the points raised by Sherr and Quirk are certainly valid and need to be considered when judging the review as a whole. On the other hand, many items included in the review have nothing to do with double blindness or placebo controls but with other methodological issues and remain valid.

It is unfortunate that most of the so-called modern provings that attempt to go back to the Hahnemannian method, such as those of Sherr, Riley, and others, were published after the cut-off date for this review (end of 1995), and mostly not in the peer-reviewed literature. Hence one should probably call this review a review of the literature of the old scientific era. It would be interesting to see how more recent modern provings would fare against the criteria adopted by the published review by Dantas et al.

• References

• 1 Dantas F, et al. A systematic review of the quality of homeopathic pathogenetic trials published from 1945 to 1995. Homeopathy 2007; 96: 4–16.
• 2 Milgrom L.R. The sound of two hands clapping: could homeopathy work locally and non-locally?. Homeopathy 2005; 95: 100-104.
• 3 Walach H. Magic of signs: why we need a nonlocal interpretation of homeopathy. Br Hom J 2000; 89: 127-140.
• 4 Walach H. Entanglement model of homeopathy as an example of generalised entanglement predicted by Weak Quantum Theory. Forschende Komplementärmedizin Klassische Naturheilkunde 2003; 10: 192-200.
• 5 Walach H., Sherr J., Schneider R., Shabi R., Bond A., Rieberer G. Homeopathic proving symptoms: result of a local, non-local, or placebo process? A blinded, placebo-controlled pilot study. Homeopathy 2004; 93: 179-185.
• 6 Möllinger H., Schneider R., Löffel M., Walach H. A double-blind, randomized, homeopathic pathogenetic trial with healthy persons: comparing two high potencies. Forschende Komplementärmedizin Klassische Naturheilkunde 2004; 11: 274-280.