DEBATE

Taking Procrustes’ Axe to Professor Fisher’s responsejep_1739 1009..1010

Donald Stanley MD1 and Scott Sehon PhD2

1Associate in Pathology, Department of Pathology, Maine Medical Center, Nobleboro, Maine, USA2Professor of Philosophy, Bowdoin College, Brunswick, Maine, USA

Correspondence

Dr Donald Stanley500 West Neck RoadNobleboro, ME 04555USAE-mail: dstanley@tidewater.net

Accepted for publication: 14 June 2011

doi:10.1111/j.1365-2753.2011.01739.x

Professor Fisher responds to our article ‘Evidence and simplicity:why we should reject homeopathy’ [1] by identifying an alternateprinciple to the one derived from Ockham [2]. Where Ockham’sprinciple can be seen as a ‘pruning’ tool, used to ensure thatexplanatory systems do not posit more than they need to get the jobdone, Fisher invokes the image of ‘Procrustes’ Axe’ as a warningagainst the dangers of chopping away too much and, consequently,losing something of value. This is a reasonable cautionary point,but its judicious application must depend first on establishing thatwhat is removed by Ockham’s razor has a value and is not, forexample, a superfluous – or even harmful – bodily part, such asunverifiable therapy. Unfortunately, Fisher has yet to show thathomeopathy really does have something of value to bring to themedical arena. Granted, homeopathic practice has a 200-yearhistory: the fact that it is still around, and arguably gaining inpopularity, might even be taken as evidence that it has ‘withstoodthe test of time’, but neither its longevity nor popularity can becounted as scientifically credible evidence since, by such standardsof proof, even astrology would rate well!

So our appeal to simplicity was based on trying to find evidenceto support the claims of homeopathy’s proponents. We introducedit in the following way:

William of Ockham famously proposed that entia non suntmultiplicanda praeter necessitatem – i.e., entities ought not tobe multiplied beyond necessity, or ‘that which is done withfewer assumptions is done in vain with more’. We proposethat a somewhat more general version of Ockham’s principleunderlies much of scientific and common sense reasoning:(S) Given two theories, it is unreasonable to believe the onethat leaves significantly more unexplained mysteries. [1]We gave examples from the history of science (appealing to the

correction of Aristotelian physics by Newton) and also commonsense reasoning (explaining why no one takes seriously certainsceptical hypotheses, such as Russell’s example of the ‘five-minute’ theory) to show the broad acceptability of the SimplicityPrinciple [1].

Fisher responds:

I am not a philosopher, but I find it hard to believe that theproblems raised by homeopathy are so unique that Ockham’sRazor has, in its 700-odd years, never encountered similarissues, so that it is necessary to create an ad hoc rider just todeal with homeopathy. Certainly it is unfortunate that theSimplicity Principle is pressed into service with suchunseemly haste and without independent examination of itsvalidity. [2]We do not see this as a fair response. It ignores the examples we

gave, and much debate in the philosophy of science, all of whichindicates that the principle is neither ad hoc nor invented simply to‘deal with’ homeopathy.

One guide in this matter is a consideration of homeopathy as awhole system of practice. W.V.O. Quine writes of ‘our vauntedsense of simplicity, or of likeliest explanation’, stating that:

Simplicity is not a desideratum on a par with conformity toobservation. Observation serves to test hypotheses after adop-tion; simplicity prompts their adoption for testing. [3]Fisher implies that simplicity has not been sufficiently tested to

remain a key element in all scientific theories: it seems not Aris-totle corrected by Newton, nor Carnap nor Quine are satisfactoryguides [2]. Nor is the Federal Drug Administration or Medicinesand Healthcare products Regulatory Agency, which demand clini-cal, controlled randomized trials testing hypotheses in order toapprove medications. And these agencies demand strict adherenceto testing, not simply observations. Granted that observations areprior to testing, but we cannot test all observations, so we choosethose which, entailing subsidiary hypotheses, allow us to designtrials to test the simplest hypotheses which entail our observations.

Fisher responds only selectively to our charge of leaving asurfeit of unsolved scientific mysteries, itemized in our previouspaper. He provides response to mysteries 1, 2, 5 and 10 whilesubsuming all the rest under one specific heading, which ‘[g]iventhe tone of their paper, they would probably have framed . . . asanother mystery’. The mysteries he does respond to are:(1) How can what is chemically indistinguishable from waterhave curative effects that non-homeopathic water does not?

Journal of Evaluation in Clinical Practice ISSN 1365-2753

© 2011 Blackwell Publishing Ltd, Journal of Evaluation in Clinical Practice 17 (2011) 1009–1010 1009

(2) How can different remedies, chemically indistinguishablefrom one another, have different curative effects?(5) Why does the law of similars apply only to homeopathicingredients and not to other medicinal substances?(10) All samples of water will have trace amounts of impurities,both natural and artificial. If infinitesimally dilute amounts ofhomeopathically chosen substance can structure water such that ithas dramatic powers, why don’t we see anything of the sort withother water samples?

His answer to (5) is a list of synonyms and seven references tothe principle of ‘similar causes similar’. Therein he introduces anew concept: ‘hormesis’ without providing any citations where theconcept has successfully been used in the treatment of humandisease. Mysteries (1) and (2) are answered with reference to apicture of waves crossing oceans, retaining their form whileexchanging molecules. We are not enlightened by this analogy.Again it is Fisher’s response (rather than our invoking the Sim-plicity Principle) that comes across as rather swift: how does ourasking these questions commit us to denying the possibility ofwaves, as Fisher claims? [2]

Fisher’s reply to (10) is the claim that homeopathic dilutions‘impose(s) a coherent structure on the entire body of the liquid’and that ‘this is supported by experimental evidence’. All of theother mysteries are subsumed under the question: ‘Why is thereno evidence that ultramolecular dilutions have effects on biologi-cal systems?’ [2] Again he claims that such evidence in factexists.

However, we found nothing in Professor Fisher’s response thatpresented new evidence to support homeopathy. The referencescited by Fisher contain a mixture of less than optimal trial meth-odology (e.g. lack of randomization and blinding); in fact his firstcited reference concludes:

At the moment the evidence of clinical trials is positive butnot sufficient to draw definitive conclusions because mosttrials are of low methodological quality and because of theunknown role of publication bias. This indicates that there is alegitimate case for further evaluation of homeopathy, but onlyby means of well-performed trials. [4]In the intervening years several other reviews of clinical trials

have been conducted and the results are similar:There is a lack of conclusive evidence on the effectiveness ofhomeopathy for most conditions. Homeopathy deserves anopen-minded opportunity to demonstrate its value by using

evidence-based principles, but it should not be substituted forproven therapies. [5]Thus, in more than 10 years there is little rigorous trial evidence

that homeopathy is effective. Why does not the homeopathic orga-nization conduct such trials? Science is, among others, open-minded to review evidence and change course if the evidence isvalidated by scientific methods.

Fisher cites ‘a meta-analysis led by Prof. Claudia Witt’ [6] asrefuting all of the other ‘mysteries’, but less than 20% of the studiesexamined were randomized and blinding was reported in fewer thansix studies, so we do not think this review supports Fisher’s claims.

Fisher makes an end run to invoke Bayesian statistics [2] butdoes not suggest what the prior probability of a scientific basis(core knowledge) for homeopathy is after 200 years; in order toperform Bayesian calculations, one has to begin with some esti-mate of the prior probability. Fisher mistakes belief with priors,calling the latter a conclusion, rather than a beginning estimate tobe subjected to clinical trials.

In fact, Fisher seems to imply that for those who experience thebenefit of homeopathy, the prior is high, whereas for researchworkers in clinical trials the prior is still much of a hypothesis. Andhow does one compare the proponents to the sceptics? Fisherseems to dismiss our mysteries because we base them on scientific‘biases’: reproducibility, consistency, reliance on approved scien-tific experimentation, etc. As mentioned above, simplicity is not anovel approach, but is at the centre of scientific thinking.

References1. Sehon, S. & Stanley, D. (2010) Evidence and simplicity: why we should

reject homeopathy. Journal of Evaluation in Clinical Practice, 16,276–281.

2. Fisher, P. (2010) Ockham’s Razor or Procrustes’ Axe? Why we shouldreject philosophical speculation that ignores fact. Journal of Evaluationin Clinical Practice, 16, 282–283.

3. Quine, W. V. O. (1960) Word and Object. Cambridge, MA: MIT Press.4. Kleijnen, J. (1991) Clinical trails of homeopathy. BMJ, 302 (6772),

316–323.5. Jonas, W. B., Kaptchuk, T. J. & Linde, K. (2003) A critical overview of

homeopathy. Annals of Internal Medicine, 138, 393–399.6. Witt, C. M., Bluth, M., Albrechet, H., Weisshuhn, T. E. R., Baumgart-

ner, S & Willich, S. N. (2007) The in vitro evidence for an effect of highhomeopathic potencies – a systematic review of the literature. Comple-mentary Therapies in Medicine, 15, 128–138.

Debate D. Stanley and S. Sehon

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