Andrea Bellelli

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      Homeopathy is a comprehensive theory about medicine and pharmacology developed by the german physician and chemist Samuel Hahnemann (Meissen 1755 -Paris 1843).
      Hahnemann's convoluted and disordered writing style, the logical complexity of his theory, and its dependence on ideas formulated in the XVIII century or before, but abandoned during the following century, have caused Hahnemann to be extensively misinterpreted by his followers. Thus the first task of any student interested in the history of this theory is to try to interpret Hahnemann correctly. The theory was unlikely and implausible at the time of its formulation and became obsolete shortly thereafter: it is a very successful error in the history of medicine.

      Why should we study homeopathy?
      We learn from our errors (and this is very useful because, should we learn only from our successes, our scientific progress would be very slow indeed). However, in order to learn, we should study our errors as accurately as we can.
      A preliminary consideration is the following: a scientific error, revealed by a discrepancy between our hypotesis and our data, may belong to either of two types. Major scientific errors occur when the fundamentals of our hypotheses are wrong and do not correspond to the empirical reality: e.g. Ptolemy's geocentric cosmology. Minor scientific errors occur when our hypotheses, though capturing something of the empirical reality, are not good or precise enough, and fail to agree with (some of) our data: e.g. Copernicus' heliocentric cosmology. The essential difference between major and minor errors is that, while both cause the theory to disagree with some experiments, minor errors can be corrected and the original theory can be amended (e.g. Kepler's revision of Copernicus' theory) whereas major errors force us to discard the theory. Failure to discard a theory flawed by a major error is usually dangerous and may lead the scientist or physician to professional malpractice. The science philosopher Karl Popper recognized this distinction when he wrote that the greatest success of a scientific theory is to be superseded by its evolution and to remain as a peculiar or simplified case of a more general one.

      Homeopathy is an elaborated theory about medicine and pharmacy, formulated by the german physician Samuel Hahnemann (Meissen 1755 - Paris 1843). The first homeopathic publication by Hahnemann is the Essay on a new principle for ascertaining the curative power of drugs that appeared in 1796 on the Praktischen Arzneikunde, a medical journal directed by Wilhelm Hufeland; the last is the sixth edition of the Organon of Medicine on which Hahnemann was working in the year of his death and appeared posthumously in 1921.

      Homeopathy is clearly a major error in the history of medical theories: a dead branch leading to nowhere, and is important to study because of what we learn from our errors. Moreover, in the case of medicine, our scientific errors are dangerous: we may damage our patients, and do even worse: race and racism, eugenics, social darwinism are obvious examples of wrong scientific hypotheses having relevance to medicine. Homeopathy is not as dangerous as other erroneous scientific hypotheses, yet it may delay diagnosis and treatment of diseases, leading to their aggravation; thus the patient should be warned on the potential risks of the practice.

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      Medicine in the first half of the XIX century
      A common misconception about the history of homeopathy, actively promoted by Hahnemann and his followers, is that it was develeoped at a time where medicine was primitive and medical therapies were only based on bloodletting and other extremely dangerous practices (the time of "heroic therapies"). Heroic therapies did indeed exist and killed more patients than they saved, but during Hahnemann's active life medical science was quite adanced and by no means was it represented by bloodletting.
      Hahnemann's life is coincident with the development of modern pathology, from Morgagni's De sedibus et causis morborum per anatomen indagatis (1761) to Rokitanski's Handbuch der Pathologischen Anatomie (1842-46). The relevance of this approach to medicine cannot be overemphasized: it represents the transition form the classical medicine of symptoms to the modern medicine of lesions.
      Medical semeiology was discovered exactly at the same time as pathology, and participates to the same change of paradigm: Leopold Auenbrugger described the percussion of the chest in his Inventum novum ((1761) whereas Theophyle Laennec published his Traite' de l'Auscultation Mediate in two editions in 1819 and 1826 to describe the stethoscope and the findings it allowed.

      Pharmacology, though limited, was far from primitive, and actually several crucial discoveries were made before or during Hahnemann's active life: e.g. James Lind published his Treatise of the Scurvy in 1753, and William Withering his Account of the Foxglove in 1785. Both works include fundamental discoveries and the application of crucial methodologies (Lind's work contains a controlled clinical trial, with control groups, on the effect of lemon juice on the scurvy).
      Vaccines and vaccinations required a long and complex evolution, of which Hahnemann saw the beginning: the cowpox vaccine against human smallpox, discovered by Edward Jenner in 1776. No other vaccine was developed till Pasteur's studies on rabies, diphtheria and tetanus.
      The age of medical microbiology was clearly impending, with the Trattato sulla Generazione by Lazzaro Spallanzani (1765) and the treatise Del Mal del Segno by Agostino Bassi (1835-1836). It is important to stress that the hypothesis of "live contagion" had been formulated one century earlier, by Girolamo Fracastoro.

      Indeed if compared to his contemporaries, Hahnemann represents an antiquate, if not obsolete, stage of medical thinking, with his insistence on therapy and therapy alone, and his neglect of the sciences that were transforming the very concept of disease:

The physician's highest calling, his only calling, is to make sick people healthy - to heal, as it is termed1.
1: It is not to weave so-called systems from fancy ideas and hypotheses about the inner nature of the vital processes and the origin of diseases in the invisible interior of the organism, (on which so many fame-seeking physicians have wasted their powers and time). Nor does it consist of trying endlessly to explain disease phenomena and their proximate cause, which will always elude him ...
(Organon, VI ed. n.1; translation by Kunzli, Naude and Pendleton, Orion Books, London 2003)

      Hahnemann's approach to medicine is in no way different from Hyppocrates' and ignores over 20 centuries of medical thinking; if Hyppocrates at his time was innovative, Hahnemann was obsolete, and represented a fully intentional declaration of ignorance ("phenomena and their proximate cause ... will always elude" the researcher).

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      Hahnemann's hypotheses
      Hahnemann's style is convoluted and his expositions of homeopathy are far from clear and rigorous. However, at least five different hypotheses can be isolated and described as highly characteristic of homeopathy:
i) the Law of the similes, often subsumed in the aphorism "Similia similibus curentur" (let the like be cured by the like);
ii) the absolute requirement that therapy should be individualized, i.e. tailored on the specific patient, under the assumption that no two patients are equal to each other;
iii) the law of the small doses, which says that upon an adequate preparation, the more diluted is the drug the more effective its action.
iv) the idea that drugs are poisons, whose effect is to be studied on healthy volunteers (proving);
v) a peculiar interpretation of vitalism.

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      Hahnemann's vitalism
      We start our analysis from vitalism, since in Hahnemann's view it is the conceptual framework that hold all other hypotheses together. Vitalism was a current medical theory in the XVIII century, that postulated the existence of one or more "vital force(s)", characteristic of the living organisms.
      The life forces were differently defined by the students of vitalism. The founder of the theory, the german chemist G.E. Stahl (1660-1734) gave two examples of the life forces: regulation of the function of the organs in the organism; and prevention of decomposition (the inevitable fate of the corpse once the vital forces abandon the body). The french anatomist F.X. Bichat (17-1801) identified the life forces as the sensitivity and reactivity of the living tissues, which may perhaps, at least in some cases, be responsible for regulatory phenomena.
      Hahnemann added to Stahl's and Bichat's ideas that the life force is "dynamic" and "immaterial"; that disease is a dynamic, immaterial perturbation of the life force; that healing is rstoration of the life force by the dynamic effect of drugs; and that the life force is located in, or has a special relation with, the nervous tissue:

In the state of health the spirit-like vital force (dynamis) animating the material human organism reigns in supreme sovereignty. It maintains the sensations and activities of all the parts of the living organism in an armony that obliges wonderment. The reasoning spirit who inhabits the organism can thus freely use this healthy living instrument the reach the lofty goal of human existence. (Organon, VI ed. n.9)

Without the vital force the material organism is unable to feel or act or maintain itself1. Only because of the immaterial being (vital principle, vital force) that animates it in health and in disease can it feel and maintain its vital functions.
1: Without the vital force the body dies; and then, delivered exclusively to the forces of the outer material world, it decomposes, reverting to its chemical constituents.
(Organon, VI ed. n.10)

Outer malefic agents that harm the healthy organism and disturb the armonious rhythm of life can reach and affect the spirit-like dynamis only in a way that also is dynamic and spirit-like. The physician can remove these pathological untunements (disease) only by acting on our spirit-like vital force with medicines having equally spirit-like dynamic effects that are perceived by the nervous sensitivity everywhere present in the organism. ... (Organon, VI ed. n.16)

      We see that Hahnemann's vitalism is the substratum of physiology, pathology and pharmacology; and that the events pertinent to these sciences occur in the realm of the non-material forces (whatever it be), rather than within the organic matter. The nervous system is specially relevant since it is implicated in "the sensations and activities" maintained by the vital force. It is difficult to grasp what exactly Hahnemann meant with the terms "spirit-like", "immaterial", and "dynamic", but there is a precise hint in Organon, VI ed., n.11, where the trasmission of measles is assimilated to magnetic attraction. It is also pertinent to recall that in Organon, VI ed., nn.286-287, Hahnemann explicitly considers magnets as therapeutic instruments and quotes Galvani and Mesmer. Finally, the magnet is listed in Hahnemann's Materia Medica Pura.

      An important consequence of the non-material nature of health and disease is that diseases lack any material cause or anatomical lesion:

... I am merely pointing out that diseases obviously are not and cannot be mechanical or chemical changes in the material substance of the body, that they do not depend on a material disease substance, but are an exclusively dynamic, spirit-like untunement of life. (Organon, VI ed., footnote to n.31)

... Since all diseases are only dynamic disturbances of the vital principle, and are not caused by anything material, by any materia peccans (a fiction that the old school in its delusion has preached and by which it has treated for thousands of years, always to the ruin of its patients), there is nothing material in these cases either, nothing that can be removed, rubbed or burned away ... (Organon, VI ed., footnote to n.282)

      Apparently in this text Hahnemann criticizes both surgery (which is thousands of years old) and pathology (which is almost its contemporary, but studies the material lesions responsible for symptoms and diseases). Disease has thus two components: one that is non-observable, the derangement of the vital force; the other, observable, the symptoms:

It is clear that human diseases are nothing but groups of certain symptoms ... (Organon, VI ed., n.71)

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      The law of similes: similia similibus curentur
      The law of the similes is the fundamental concept of homeopathy (= same pathology) and states that:

In the living organism a weaker dynamic affection is permanently extinguished by a stronger one, which, though different in nature , nevertheless resembles it in expression. (Organon, VI ed., n.26)

      In order to take advantage of this "natural law" the wise homeopathic physician administers the patient a drug which causes an intoxication whose symptoms are similar to his disease. In this way the original disease is replaced by the intoxication, that the physician is able to heal by interrupting the administration of the drug. We may call this practice a therapeutic disease:

So in homeopathic cure this vital principle, which has been dynamically untuned by the natural disease, is taken over by a similar and somewhat stronger artificial disease, through the administration of a potentized medicine that has been accurately chosen for the similarity of its symptoms. Consequently the (weaker) natural dynamic disease is extinguished and disappears; from then on it no longer exists for the vital principle, which is controlled and occupied only by the stronger artificial disease; this in turn presently wanes so that the patient is left free and cured. (Organon, VI ed., n.29)

      I discuss below the concepts of "potentized medicine" and "accurately chosen", which refer to the hypotheses of the small doses and individualization. At present I am more concerned with the idea of the therapeutic disease. This idea appears early in Hahnemann's system, being already present in the 1796 Essay on a new principle:

Every powerful medicinal substance produces in the human body a kind of peculiar disease; the more powerful the medicine, the more peculiar, marked, and violent the disease. We should imitate nature, which sometimes cures a chronic disease by superadding another, and employ in the (especially chronic) disease we wish to cure, that medicine which is able to produce another very similar artificial disease, and the formed will be cured; similia similibus. (The lesser writings of Samuel Hahnemann, trad. Dudgeon, p.265)

      We may follow the evolution of Hahnemann's idea of the therapeutic disease from a possible event (in 1796) to a general law of nature (in the essay The medicine of experience, published in 1805):

When two irritations greatly resemble each other, then the one (the weaker) irritation, together with its effects, will be completely extinguished and annihilated by the analogous power of the other (the stronger). (The lesser writings of Samuel Hahnemann, p.447)

      R. Hahel, homeopathic physician and the first of Hahnemann's biographers, reports that Hahnemann conceived the idea of the therapeutic disease and the law of similes in 1790, while translating a medicine textbook by the scottish physician W. Cullen. Hahnemann thought that Cullen's explanation of the anti-ague properties of cinchona bark was unsatisfactory and started an experiment on himself. He took four drachms of cinchona every day for a week in order to test the effect of the drug. The dose was high and Hahnemann suffered the intoxication we call cinchonism, which looked to him similar to malaria. Thus he speculated that cinchona cures malaria because it causes a similar disease, and the law of similes was born.

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      Hahnemann thought that every disease is due to a non-observable derangement of the life force, whose observable counterpart of is the totality of its symptoms (Organon, VI ed., n.17). He thought that the coexistence of two diseases in the same individual was impossible and self-contradictory, as it would imply two totalities of their symptoms, and based his hypothesis of the therapeutic disease on this hypothesis.
      He was adamant in stating that no two patients are equal, because of even minute differences in the totality of their symptoms:

Hence it happens that with the exception of those few diseases that are always the same, all others are dissimilar and innumerable and so different that each of them occurs scarcely more than once in the world, and each case of disease that presents itself must be regarded (and treated) as an individual malady that never before occurred in the same manner and under the same circumstances as in the case before us, and will never again happen precisely in the same way. (The medicine of experience, 1805, in The lesser writings of Samuel Hahnemann, p.442)

      Today Hahnemann's reasoning is hard to follow, since we know that two diseases can coexist and that in the totality of the symptoms we should distinguish what is pertinent to one disease and what is pertinent to another; moreover we know that two istances of the same disease may differ, even significantly. However in classical greek medicine there were schools privileging Hahnemann's approach, and others contrary to it, and the definitive acceptance of the modern view point is probably linked to the discoveries of Koch and Pasteur. Half a century before Pasteur Hahnemann's point appeared plausible.
      The british homeopath R. Hughes, writing some fifty years after Hahnemann's death, remarked that the master's thought had some flaws on this point since it neglected the obvious consideration that there are typical and atypical cases of malaria, that all respond to quinine. He also remarked that quinine is ineffective in cases of recurrent fever of non-malarial origin, that may closely resemble typical cases of malaria. Thus, the fact that two instances of the same disease differ from each other is by no means an indication that they should be considered or treated differently.
      To Hahnemann, individualization was the obvious consequence of the fact that no two patients suffer of the same disease and that for the homeopathic remedy to be effective it should cause symptoms as similar as possible as those of the disease (i.e. the drug should be the so called simillimum).

      A very relevant consequence of individualization and of the "no two identical diseases" hypothesis is that the homeopathic diagnosis is not the assignement of each disease and each patient to a class, according to a finite nosography: the homeopathic diagnosis is the detailed collection of the totality of the symptoms of the patient. Some modern homeopaths have stated this point very clearly:

Homeopathy would be an especially appropriate referral for patients in whom a diagnosis cannot be established. Homeopathy's advantage derives from its individualizing the remedy to the uniqueness of the patient's symptoms, bypassing the need for diagnosis altogether. (Gray, Homeopathy: science or mith?, North Atlantic Books, USA, 2000, p.157)

      This approach is the cause of the major risk of homeopathy: the patient may go to the homeopathic physician with a curable condition (e.g. a cancer in an initial stage, a localized infectious disease, a cerebral or cardiac ischemia), be cured for his/her symptoms while no diagnosis is made, and delay a real diagnosis and an effective treatment till his/her disease has progressed beyond the possibility of cure.

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      Potentization, or the power of small doses
      When Hahnemann first conceived the law of similes, he used his drugs at the same doses of other physicians. However in a short while he started proving new drugs and to play with their dosage. Since his drugs were chosen on the basis of the symptoms they produced, his first attempt was to reduce their dosage, to reduce their toxicity. In order to reduce the dose while maintaining an amount of substance that he and his patients could manage he prepared his drugs in solutions, serially diluted by a factor of 10 to 100.
      Hahnemann considered attenuations these dilutions and was perplexed to observe that even extreme dilutions did not diminish the curative power of his drugs (we doubt that his drugs had any effect whatsoever at any dose, except their toxicity; thus we are not perplexed by the fact that dilution did not affect the effectiveness of the therapy; if the patient was cured this must have been due to reasons independent of Hahnemann's therapy).
      Hahnemann's explanation of the effect of dilution, at the time, was that the dilution caused a minute dispersion of the drug, and thus favored its intimate contact with its targets, the nerves, where the life force is located:

Let this [the solution of the drug] be as weak as it may, in its passage through the stomach it comes in contact with many more points of the living fibre, and as the medicine does not act anatomically but only dynamically, it excites much more severe symptoms than the compact pill containing a million times more medicine (that rests inactive) is capable of doing. (On the power of small doses of medicines, 1801, in The lesser writings of Samuel Hahnemann, p.387)

      At a later stage of his career, Hahnemann became convinced that dilution increased the effect of the drugs, and his attenuations became potentizations or dynamizations. He had already reached the point at which not a single molecule of the drug was present in the dose of liquid he administered to his patients, thus our point is not the chemical composition of Hahnemann's drugs: we investigate Hahnemann's reasoning. The basic idea underlying the concept of potentization is that serial dilution and repeated succussion (agitation) destroys or removes the material part of the drug and releases its pure dynamic component:

... the smallest dose of a properly dynamized medicine - in which calculation shows that there is only an infinitesimal amount of material substance left, so little that it cannot be imagined or conceived by the best mathematicians - exerts far more healing power than strong material doses of the same medicine. This very subtle dose, which contains almost nothing but the spirit-like medicinal force released and freed, can bring about, solely by its dynamic power, results impossible to obtain with crude medicinal substances, even in massive doses. (Organon, VI ed., footnote to n.11)

      Thus: (i) Hahnemann is perfectly aware that no material substance of the original drug is left in his dilutions; (ii) the drug would in any case act because of its force, rather than because of its mass; (iii) dilution gets rid of the useless mass of the drug, while releasing its force. All the critics who pointed out, then and now, that homeopatic dilutions eliminate the drug are served! (provided that we believe in the force).
      So real had become the phenomenon of dynamization in Hahnemann's mind that he warned his followers against its excess:

If we wish, for example, to attenuate a drop of the juice of sundew to the decillionth, but shake each of the bottles with twenty or more succussions ... the medicine ... will have become so powerful ... that a drop of it given in a tea-spoonful of water would endanger the life of such a child ... (How can such small doses ..., 1827, in The lesser writings of Samuel Hahnemann, p.733)

      So astonishing was Hahnemann's claim that the poor english translator (the british homeopath R. Dudgeon) added a footnote to explain that in the german text "it is not stated that such a preparation did endanger the life of any patient, but only that it would (wurde) endanger it": nobody was killed by excess dynamization of an homeopatic drug!

      The paradox of the potentization of poisons.
      There is a paradox in the concept of potentization, that deserves specific attention. The paradox belongs entirely to the theory: it negates other, equally important aspects of homeopathy. Simply stated the problem is as follows: homeopathic drugs are poisons whose scope is to cause the therapeutic disease. The therapeutic disease will substitute the natural disease and is under the control of the physician who can interrupt its course by removing the drug. Healing ensues. Under this premise (the therapeutic disease; the law of similes) it is perfectly logical to attenuate the effect of drugs, in order to reduced the severity of the therapeutic disease to the bare minimum required to replace the natural disease. It is illogical to try to potentize the effect of the drug. Hopefully the whole theory is empirically flawed and its hypotheses do not correspond to anything real: thus dilution, if anything, makes homeopatic preparations innocuous.

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      Given that homeopathy requires its drugs to cause symptoms similar to those of the patient's disease, it was imperative for Hahnemann and his followers to test the effects of known drugs and of new substances (most often of vegetable or mineral origin). This practice is called proving. Indeed the law of similes was conceived as a consequence of Hahnemann's proving of Cinchona. Homeopatic provings are tedious collections of substances and the symptoms they cause, and are usually called Materia medica. Hahnemann himself published three such collections: the Fragmenta de viribus medicamentorum positivis, sive in sano corpore observatis (1805); the Materia medica pura (6 voll. 1811-1821); and the Chronic diseases (1828-1830). The last two had a second edition each.
      A confusing issue is that of clinical proving: Hahnemann suggested that homeopaths should test known drugs to ascertain whether they cause the symptoms they cure:

We should endeavour to find out if the millefoil (Achillea millefolium) cannot itself produce hemorrages in large doses, as it is so efficacious in moderate doses in chronic hemorrhages. (Essay on a new principle, 1796, in The lesser writings of Samuel Hahnemann, p.269)

      Did Hahnemann prove the millefolium? The plant does not appear in any of his treatises. If he had, he would have disproven his theory: for even in the XVIII century it was plainly obvious that lemon juice cured the symptoms of scurvy without causing them, and the millefolium does not cause hemorrhages. Some homeopaths (but probably not Hahnemann) took Hahnemann suggestion one step further and assigned to the drugs of conventional medicine the symptoms they cure, without actually proving them. This malpractice is called the "clinical proving".

      There is some confusion among homeopaths on the dosage of drugs in the practice of proving. This is because at the beginning of his career Hahnemann suggested that proving should be carried out at high doses of the drug (as he himself did in the case of Cinchona bark) and therapy at low doses (high dilutions; high potencies). Later in life Hahnemann suggested instead that the thirtieth dilution should be used as a base for both provings and therapy.

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      Some controversies between homeopathy and medicine
      Hahnemann vehemently criticized his colleagues and the apothecaries, who of course retorted. Some of the most relevant arguments are listed below.
      Homeopathy cures the disease, conventional medicine cures the symptoms (and vice versa).
      This is perhaps the most classical accusation exchanged between physicians and homeopaths, since Hahnemann's times. Hahnemann accused contemporary physicians to establish diagnosis according to the principal symptoms of their disease, those which are common to most patiens (the communia of classical medicine). He thought that the disease consists of the totality of the symptoms (the communia and the propria, characteristic of each patient), and that every disease case was unique. Because of this discrepancy, he thought that only the homeopathic approach addresses the whole disease, whereas classical medicine only addresses some of its symptoms.
      Conventional physicians retorted the accusation: they claimed that the disease is not the sum of its symptoms, but their cause. In their view diagnosis was akin to classification, an idea that Hahnemann refused or considered useless. Thus, conventional physicians accused Hahnemann of treating the symptoms, rather than the disease (identified with its diagnosis).

      Homeopathy is a gentle and "natural" way of curing
      Hahnemann thought that the natural healing process was rarely successful: he wrote that, if our life force were able to overcome the disease we would not even fall ill. He though that spontaneous healing was not the result of the defense mechanisms of our organism, but rather the effect of a casual and unintended homeopathic therapy (i.e. the patient might ingest some homeopathic remedy with the diet, and be cured).
      Hahnemann accused contemporary physicians of trying to imitate the dangerous healing mechanisms of our body: e.g. he accused them of practicing bloodletting as an imitation of spontaneous hemorrhages, or of administering laxatives to imitate diarrhoea. This was a distorted idea of contemporary and classical medicine, which was wrong in a different way: physicians practiced bloodletting because, according to the theory of humors, they thought that blood was in excess in the patient body.