Plausibility and evidence: the case of homeopathy

Abstract

Homeopathy is controversial and hotly debated. The conclusions of systematic reviews of randomised controlled trials of homeopathy vary from 'comparable to conventional medicine' to 'no evidence of effects beyond placebo'. It is claimed that homeopathy conflicts with scientific laws and that homoeopaths reject the naturalistic outlook, but no evidence has been cited. We are homeopathic physicians and researchers who do not reject the scientific outlook; we believe that examination of the prior beliefs underlying this enduring stand-off can advance the debate. We show that interpretations of the same set of evidence--for homeopathy and for conventional medicine--can diverge. Prior disbelief in homeopathy is rooted in the perceived implausibility of any conceivable mechanism of action. Using the 'crossword analogy', we demonstrate that plausibility bias impedes assessment of the clinical evidence. Sweeping statements about the scientific impossibility of homeopathy are themselves unscientific: scientific statements must be precise and testable. There is growing evidence that homeopathic preparations can exert biological effects; due consideration of such research would reduce the influence of prior beliefs on the assessment of systematic review evidence.

Uso y actitudes frente a los medicamentos naturales y homeopáticos en pacientes pediátricos: una encuesta entre médicos colombianos

“…Por lo tanto, sería de gran importancia disponer de más información sobre la eficacia de la homeopatía. El mecanismo de acción de la homeopatía con base en ingredientes diluidos es aún un tema de ardua discusión [19]. Se han publicado recientemente teorías sobre la posible explicación del mecanismo de acción de la homeopatía en el contexto de la nanoinvestigación [20], pero todavía se encuentran en discusión.…”

A Randomized Open Comparative Clinical Trial on the Effectiveness, Safety and Tolerability of a Homeopathic Medicinal Product for the Treatment of Painful Teething in Children

“…Despite these positive finding, the effectiveness of homeopathy is still heavily debated [24]. Based on the perceived implausibility of any conceivable mechanism of action for homeopathy, specifically the highly diluted medications, all (placebo)-controlled studies and other available evidence on homeopathy is rejected [25] or regarded as placebo effects [26].…”

Homeopathy: Meta-Analyses of Pooled Clinical Data

“…Socioscientific issues are also relevant to discuss [19]. In the meantime, the issue continues to be a struggle between believers and non-believers, guided by plausibility bias [20]. …”