ABSTRACT
Scientific medicine and homeopathy are interesting case studies for the ongoing project of demarcating science from pseudoscience. Much of the demarcation literature formulates abstract criteria for demarcating science from pseudoscience generally. In service of a more localist approach to the demarcation problem, I reconstruct a specific demarcating difference, the like comparison criterion, invoked by nineteenth century adherents to an early model of scientific medicine. If it is to remain relevant today, I argue that the like comparison criterion must be updated in our current era of epidemiological, evidence-based medicine to recognize the importance of assessing study bias and mechanistic implausibility in contemporary medical science.