The Dilution of Homeopathy

Similia similibus curantur. – Samuel Hahnemann

If you must have surgery, will you elect the homeopathic option for anesthesia? – Hoca Camide

Samuel Hahnemann (1755 – 1843) was a brilliant man. A polymath fluent in many languages and holder of a medical degree granted by the University of Erlangen in 1779, Hahnemann became an outspoken critic of what he later termed allopathic medicine.

But Hahnemann objected most to the centuries-old practice of bloodletting, a practice staked on the belief that an excess of blood causes disease by upsetting the balance of bodily humors. Hahnemann’s objections to this 2,000-year-old practice were well-taken, although bloodletting is not allopathic. Allopathy treats disease with antagonists, as today, bacteria are fought with fungi (antibiotics).

Homeopathy, Hahnemann’s innovation, propounds to fight disease with protagonists, that is, substances said to produce the same symptoms in healthy individuals. As is well known, the trick is that these substances are no longer detectable in the homeopathic preparation. Continual aggressive dilution removes the molecules of interest to the point that they quantum-probabilistically shine in absentia. Homeopathy, in other words, is not even snake oil.

The inverse dose dependency, the idea that the most diluted medicine is most effective, is the most astonishing claim of homeopathy. If a homeopath with a wicked large microscope cannot tell the difference between a properly diluted preparation and an otherwise identical substance that had never contained the homeopathic ingredient in the first place, then how could a patient or the patient’s body?

Popular Homeopathy

Homeopathy remains a popular type of “alternative medicine” - even among veterinarians (Stanossek & Wehrend, 2022). I use scare quotes lest you think I endorse the idea that homeopathy deserves the label. This popularity is a puzzle to the realist, or rather, the person who believes that all humans are realists. Of course, they are not. Humans believe plenty of things for which there is no evidence (Krueger, 2022a). They believe things against which contrary evidence is readily available (as was the case with regard to bloodletting).

German pharmacies offer homeopathy as a matter of course.

Source: W. Best

Besides habit, a conducive cultural atmosphere, confirmation bias, and survivor bias (the deceased are not around to testify that the medicine did not work; Dawes, 2006), the twin ideas of [a] “At least it won’t do harm” and [b] “At least we are doing something” hold sway. Both ideas facilitate action without apparent grounds for regret (Baron & Ritov, 2004). The first idea is epistemically weak, and it is deceptive in that it invites a positive attribution of any improvement to the delivery of the homeopathic preparation. Interestingly, Hahnemann did not subscribe to this idea because he predicted initial adverse effects, specifically on the healthy. He was even wrong about that (Stub et al., 2016).

The second idea is an overgeneralization of the adaptive belief that goal-attainment requires appropriate, that is, instrumental, action. Doing something might make a person feel in control when doing nothing has precisely the same effect, namely, none.

A third idea that aficionados may adduce is the superficial similarity between homeopathy and vaccination. Indeed, vaccination works in a homeo sort of way. The healthy are exposed to a small dose of an illness-inducing substance for their immune system to be stimulated to fight. Vaccines, however, neither cure the sick nor do they come in the form of molecular memory. As to woo-woo beliefs (Krueger, 2022b), one wonders if those who stand against vaccination also support the use of homeopathy.

It is unlikely that many homeopathy clients reflect much on the reasons for their loyalty. It is doubtful that many people even know the the underlying theory. Instead, they may simply mistake homeopathy for another kind of herbal medicine – and welcome its gentle ecological. It sounds rather like allopathy without side effects.

Cargo Cult Homeopathy

A cargo cult science is a set of activities that pretends, in all seriousness, to be a legitimate science without delivering the goods (Feynman, 1974). It is, in other words, science sub specie ludi (Huizinga, 1949). The field of homeopathy sports colleges, professional societies, degrees and accreditations, and peer-reviewed journals. It seeks to look like a science and indeed mistakes itself for one. The relationship between science and pseudo-science is asymmetrical. Only the former can debunk the latter, and only the latter craves the credibility of the former. We have yet to see allopaths trying to refute homeopaths’ claims that allopathic medicine is bogus.

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Borrowing Other People’s Memories

Consider what appears to be the most prominent meta-analysis on the efficacy of homeopathy. Writing in the prestigious British medical journal The Lancet, Shang et al. (2005) concluded that the effects of homeopathy are nugatory. The data are summarized in two funnel plots where the size of the study sample (represented by the standard error of measurement) is graphed against the odds ratio (treatment effectiveness relative to placebo control). For conventional treatments, larger studies produce smaller effects, but these effect sizes do not converge on zero (or an odds ratio of 1.0). For homeopathic treatments they do, and this is damning. A more recent meta-analysis replicated this pattern of results (Mathie et al., 2017). High-quality studies showed no evidence for homeopathy; low-quality studies did.

It is damning because it suggests that many small-scale (and likely poor quality) studies overestimate the true effect. As a result, even a weighted-average effect size overestimates the true effect. Small studies should be discounted if, on average, they yield stronger effects than large studies.

This fundamental statistical caution is lost on the apologists. Hahn (2013, p. 376) objected that,

The funnel plot is flawed when applied to a mixture of diseases, because studies with expected strong treatments effects are, for ethical reasons, powered lower than studies with expected weak or unclear treatment effects.

He suggested, without evidence, that smaller studies yield stronger effects for good reason. Why this would not be the case for conventional treatments is anyone’s guess.

If Hahn’s argument were valid, it could only apply to conventional treatments because allopathy has a positive, and not a negative, dose-dependence. What might be the ethical reason that would make homeopaths hesitate to run a larger sample because they are concerned about large effects? Does this mean they would deliver weaker (i.e., less diluted) preparations? Would, as the old joke goes, homeopaths worry about patients dying of OD?

Offbeat

I once had a productive relationship with a homeopath. He pretended to give me medicine and I pretended to take it. - Hoca Camide

Hahnemann was not the last astute mind wasting itself on a bad idea. I might find peace with the thought that homeopathy will be around in the largely harmless way of background noise. What bothers me is that good people pay good money for it, that the purveyors get money for nothing – to the tune of 5.39 billion USD in 2017. One almost admires the gall. We must, it is true, remember reading the small print conceding (or proudly pointing out) that the preparation contains nothing but the memory of molecules That is some expensive memory!