The law of similars: current biases in its application

Abstract

Background and Aims. Homeopathic prescription is based on the so-called law of similars, i.e. 1) on a patient sharing symptoms with the artificial and reversible disease caused by a drug taken in the state of health in a proving (Materia Medica Pura); 2) on systematic observations of pathogenetic effects due to accidental drug abuse (toxicology). However, in contemporary homeopathy, distortions in the application of the law are not infrequent, and they will be considered here.
 Methods. Two main biases are described and analyzed: 1) the shift towards the law of the same, concerning methods like isopathy and homotoxicology; 2) the a priori attribution of therapeutic properties to high dilutions of a given substance. The first twist can be retraced to the extension of the concept of drainage. Drainage is aimed to restore a blocked function by making use of a drug with affinity for a given anatomic district or a specific function – tropism. To some extent this technique is compatible with classical homeopathy, though not based on the law of similars. In any case, drainage has limited effects and typically precedes the use of a simillimum identified within a holistic view. The second kind of distortion is due to the influence of the ancient doctrine of signaturae. In the Organon S. Hahnemann warns against the temptation of ascribing to remedies any effect or property without a preliminary screening through proving. However, while doctrine of signaturae was regarded by classical masters as a further support to experimental findings, rather than being used to infer ex novo substance properties, several homeopaths have expanded its application to the point of using it as an alternative approach to Materia Medica.
 Conclusions. In a picture of contemporary homeopathy based on these premises, we can draw a line which goes from methods combining isopathy and drainage, acting only on a local level, to approaches somewhat related to the doctrine of signaturae, postulating a priori essences of remedies apart from experimental research. Classical homeopathy (centered on the original concept of simillimum) lies at the middle. The two opposite ends of the picture remind of the Cartesian dichotomy of reductionism. This classification, far from representing a continuum, hints at the danger of an allopathic drift of homeopathy. We fear that any attempt to reconcile strongly heterogeneous principles and views in the so-called “integrated” approach to disease is a chimera, and that it would benefit market rather than the “true art of healing” as originally conceived.