Education And Debate

Alternative (complementary) medicine: a cuckoo in the nest of empiricist reed warblersCommentary: A warning to complementary medicine practitioners: get empirical or else

BMJ 1999; 319 doi: (Published 18 December 1999) Cite this as: BMJ 1999;319:1629

Alternative (complementary) medicine: a cuckoo in the nest of empiricist reed warblers

  1. Leonard Leibovici, professor (leibovic{at}
  1. Department of Internal Medicine E, Beilinson Campus, Rabin Medical Centre, 49100 Petah-Tiqva, Israel
  2. Department of Clinical Epidemiology and Biostatistics and Department of Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5

    Proponents of alternative medicine can be compared to cuckoo chicks in that they are using false signals to gain nourishment from a legitimate scientific and medical frame. Rather like the reed warbler parent,1 the guardians of this frame are not equipped to recognise loud signals as false.

    Warbler chicks increase both their gapes and calling rates as they grow hungry. When the parent is a reed warbler and the nestling is a cuckoo chick, the cuckoo produces a loud begging signal. The sound not only matches the total calling rate of four warbler nestlings but rises so fast as the cuckoo grows that it soon sounds like eight little warblers. This signal fits overwhelmingly with what the warblers want to hear, if only imperfectly with what they expect to see. Still, it is so clamorous that the warbler parents ignore the missing visual cues and feed the cuckoo chick—to the detriment (and ultimately death) of their own offspring. 1 2

    Summary points

    Empiricists are not equipped to recognise the loud signals of alternative medicine as false

    A deep model of the physical world is essential for choosing hypotheses to be tested and for learning from failures

    Practices of alternative medicine that do not fit even at the far fringes of the model should not be tested in humans

    Our decisions on which practices to test and which to adopt should be based on three things: empirical evidence; our deep model of physical world; and our commitment to the wellbeing of our patients

    Two conceptual frames are relevant to the present discussion. One (the empirical-social construct) is ill equipped to deal with the clamour of alternative medicine. Like the warbler, it ignores the absence of vital cues because of the loud signal. The other frame (the “deep model” empirical one) has deficiencies but is better protected against a loud false signal. Even firm empiricists, should use some of the protective mechanisms offered by the second frame. Both frames are defined by several assumptions.

    The first frame: empiricism and social constructs

    Medicine is a social construct

    For example, the “ABC of Complementary Medicine” defines medicine as the “politically dominant health system of a particular society or culture in a given historical period.”3 Alternative medicine is defined as practices outside this construct.

    Boundaries of medicine are defined in social terms

    Thus the questions used to define these boundaries are: what is acceptable? is it in common use? how is it paid for? what political structures support it? what social needs does it fulfil? Articles or reviews that have as their main purpose answering these questions are an important service.

    We firmly believe only in empirical proof

    We are lucky to live in a time when a potent methodology was developed to search for empirical proof. Its epitome is the randomised controlled trial.

    The origin of hypotheses does not matter

    Empirical proof is so powerful that we really do not care about the origin of the ideas we examine. The opposite is true: practices or hypotheses from everywhere are welcomed to be tested. It fits with our self image of open mindedness and fairness. When the boundaries of medicine are shifting (and they shift because of social and political forces, by definition and belief) we will be able to use our empirical methodology to test what should or should not be adapted from the practices that are straddling the border now.

    Our mission is (and always was) mainly to alleviate suffering

    We should not be too squeamish about using anything that does it.

    Be humble

    A combination of old-time patriarchalism and “scientific” hubris spawned a hardhearted and conceited breed in medicine. A bit of competition will do no harm.

    The second frame: empiricism and deep models

    The scientific method changed the practice of medicine

    Medicine is a social construct. However, the most powerful tool we have acquired is what, for lack of a better term, can be called scientific medicine. It is such an effective tool that it changed radically the practice of medicine (and probably society as well, by changing life expectancy) in the past century.

    Scientific medicine, one of the kernels of medicine as we practise it, is not a social construct. Thus alternative medicine is defined as practices that do not fit into its boundaries, but rather are based on rules of anthropocentric magic.

    Scientific medicine consists of empirical testing and a deep model

    The core of scientific medicine is not empirical testing alone. Empirical proof (elicited using the best methodology) is very important. Standing alone, however, empirical proof might (and has) failed us. By definition, it is not protected from a small chance of error. Even with the best methodology, it is not easily guarded from inadvertent introduction of bias and from fraud.

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    The signals of the cuckoo chick ensure that it gets well fed by the reed warbler parents


    Empirical testing has been used for the past few thousand years —sometimes even with surprisingly correct methodology. In the Louvre there are Babylonian clay figures of livers of sacrificial animals that were modelled before major battles, and the prognostication has been written on them before combat. If you were to be presented with a set of one thousand prognostications like these, all made before the battle and all of them successful, would you believe in the method? Or would you be looking for the hand of the priest? Even the most ardent empiricist will reach a limit of credulity in empirical proofs.

    Scientific medicine was successful because it combined empirical proof with a deep model. This combination guards it, to a great extent, against chance, bias, and fraud. We will accept an empirical proof if it fits (even at the far, nebulous margins) the model of the physical world that we use. The model applies to the whole of the physical world, including our bodies. This model changes. A scientist can be defined a person who looks for explanations at the far fringes of the deep model and brings these fringes to the centre.

    The building and falsification of bold hypotheses is at the core of the scientific method. However, there are hypotheses that cannot be accommodated even at the fringes: that livers of sacrificial beasts will predict the future; that a substance that causes complaints similar to the ones observed in a patient will, if diluted to an infinitesimal concentration, cure them.

    The deep model is essential for choosing hypotheses and learning from failures

    A deep model is necessary to choose the hypotheses we are going to test. Resources are limited. The moment we give up on the model, we should test everything. How do we choose what to test? There are thousands of practices, with a multitude of variations. It is easy to show that a way chosen from the framework of the “social construct” and does not use a deep model will soon encounter paradoxes and contradictions.

    Re-examining the deep model is the only way to use the failure of a trial or an experiment to move on. Failure should prompt a scrutiny of the model (the experiment was correct: how should we change the model, and which further experimentation will test it?); or a critical look at the experiment. After each unsuccessful trial in acupuncture there comes a flurry of letters saying that the study failed because the traditional method was not used, or that it was used; that it failed because needles were inserted too deep, or not deep enough, or twirled once too many times. We have no way of choosing from these explanations because we have no idea of how the treatment is supposed to work. If we have no idea, we must try all the alternatives.

    Scientific medicine does not contradict compassionate and emphatic practice of medicine

    On the contrary, the offer of partnership in the way to health and well being should include the explicit science of medicine. We encounter patients with ideas and frames of mind different from ours. Scientific medicine, including a common and basic model of the physical world, can be explained and offered to most patients, without reaching a conflict with their beliefs and religion. But magic (ways to influence directly the “basic stuff” of the universe) is contrary to religious beliefs and is an effrontery to the common sense of our patients.

    Back to the warbler nest

    Advocates of alternative medicine signal loudly to the adherents to the first frame: they clamour that empirical testing is what really matters. If a procedure has not been tested, it has the legitimate status of “test pending.” There is no way to differentiate between good and bad candidates for testing among the pending procedures.

    The boundaries between medicine and “complementary” medicine can be defined by surveys and public opinion. This is what the public wants. If you are against these practices, you are outmoded, narrow minded, conventional, disrespectful of the common wish. Attesting to the success of this signal is the BMJ's ABC of complementary medicine,3 a JAMA editorial,4 and many surveys on the use of alternative practices. 5 6

    What is so bad about responding to these signals? None of us would renounce the postulates of the first frame. But without keeping in mind the checks of the second frame, we may end up by upholding practices which, given an explicit choice, we would rather not—we would throw our warbler chicks out of the nest.

    The deep model of alternative medicine is anthropocentric magic. The explanations of the practitioners of alternative medicine are giving our patients a set of magical rules to control the physical world, rules that have the human as the fulcrum. They are saying that herbs are beneficial and can do no harm; a substance that causes complaints similar to those observed in a patient will cure them if diluted to an infinitesimal concentration; “we will adjust your Qi force”; these are phenomena that work only on the living human, and not on any other component of the physical world. I would guess that none of us are firm believers in magic. Honouring our patients, are we ready to offer them these explanations?

    All alternative practices are effective in minor ailments, usually waxing and waning ones, but not in severe conditions. These various interventions (needles and drugs, colours and lights, manipulation of the spine and caressing of soles, single atoms and megadoses of vitamins) are effective to prevent the common cold, but not to treat pneumonia; to treat asthma, but not anaphylactic shock. What explanation do we have for this dichotomy?

    Using the “social frame” for definitions, we are exposed to intense manipulations. Manipulations of the media and the political system can create quite an impression about what belongs to the “politically dominant health system.” Lately we have witnessed these manipulations time and again.

    If we start with a very low, infinitesimal, belief in our hypothesis, even a successful randomised trial will not sway us by much. Our belief in the efficacy of the treatment will remain low. Thus a controlled trial of homeopathic drugs in humans is unethical: a successful trial, without an explanation, will lead to naught.

    The second frame has obvious shortcomings. The deep model has overtones of a religious orthodoxy. But it is guarded from becoming such by constant testing and change, and by holding no idea of the physical world as sacred. By using our model of the world as a filter, we might lose some worthy ideas.7 But our loss of sensitivity will probably be more than compensated by the gain in specificity. And worthy ideas have a way of returning.


    The core of scientific medicine has withstood tests again and again during the past century. For the first time in thousands of years we have a system that works. Please ask yourselves if by embracing the first frame entirely we do not undermine a good thing instead of finding ways to repair its faults.

    I am convinced that we should base our decision on whether to adopt a practice or not on three legs: empirical evidence; our deep model of the physical world; and our commitment to the wellbeing of our patients.


    • Competing interests None declared.


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    Commentary: A warning to complementary medicine practitioners: get empirical or else

    1. R Brian Haynes, professor (bhaynes{at}
    1. Department of Internal Medicine E, Beilinson Campus, Rabin Medical Centre, 49100 Petah-Tiqva, Israel
    2. Department of Clinical Epidemiology and Biostatistics and Department of Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5

      Cuckoo indeed! Practitioners of complementary medicine beware: conventional doctors are adopting some of your young as if they were their own Soon you won't be needed by a society that would like to have alternative treatments paid for by tax dollars, not directly out of pocket, provided no doubt through “one stop shopping” at a conventional doctor's office. And conventional doctors won't be kind to alternative treatments. Most won't have the training to deliver them. They will mix them with their own treatments, treatments that may counteract or drown any beneficial effects. So, complementary practitioners, start taking care of your own young.

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      How about a randomised controlled trial of the stone age diet?

      (Credit: CEPHAS)

      Take care of your own young

      And how might you go about this, you ask? Embrace empiricism, of course. In the long run, it is the only way to gain the legitimacy that you seek. But don't bother with “deep models.” Deep models are for snobs, oppressors, and wishful thinkers. The flat earth, phlogiston, bleeding, cupping, oppression of women, the Aryan Race—what are these but “deep theories”? Any good empiricist can attest to the facts that theories are cheap and sound evidence is hard won. The human mind can concoct a theory to support any set of notions and observations. The path that conventional medicine is currently—very recently—treading has brought it past many useless and obnoxious treatments, through adopting a scientific, show-me-the-evidence, approach. That convincing evidence is difficult to secure is protection enough against wasting time and effort to test frivolous health claims.

      Does conventional medicine voluntarily test its ministrations? Some of its practitioners have contributed to the science, but most have cooperated only to the extent that legislation has decreed and publicly funded support has directed. Yet, society has enormously rewarded the medical profession for its grudgingly empirical approach: doctors are well paid, medical research is richly supported by increasing amounts of public funds, and society has legislated that some companies must pay empiricist research doctors to test their products.

      Empiricism and reward

      The spotty nature of the evidence for many medical treatments, however, illustrates that the “empirical champion” status enjoyed by the medical profession is largely externally driven. Public and professional support is mainly directed towards selected treatments, notably medications. What about the non-pill-like treatments of medicine such as surgical procedures, bed rest, machine based treatments such as ultrasound, “counselling,” tincture of time, and so on? Do they work? Who knows? Do doctors get paid for them? You bet. No profession should be fully trusted to test itself. The medical profession can't take much of the credit for its current state of empirical foundation. And medical doctors aren't above using its empirical support to discredit competitors. If you complementary practitioners want to retain and grow your turf, wake up to the benefits of empiricism!

      A call to action

      So what should complementary medicine specialists do? Form professional societies. Demand to be regulated (in the usual genteel professional fashion). Set standards for practice and use these standards to certify practitioners. Send your best and brightest for research training and have them seek money for research from funding agencies (no better time for this than now). Demand that manufacturers of complementary products be regulated too—some of them are getting away with fraud and murder and will disgrace you in the process. Educate your practitioners to appreciate evidence from empirical research. Form a Cochrane Complementary Alternative Medicine Review Group to summarise the evidence that supports or refutes your practices. Proudly endorse the treatments that have been shown to work, and forsake the ones that don't. (Perhaps you could begin by getting rid of some of the treatments that are useless or harmful, such as β carotene. 1 2) Then you can afford to be as prideful as conventional doctors.


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