Valuing and Evaluating Evidence in Medicine

Medical decisions should be based on good evidence. But this does not mean that health care professionals should practice evidence-based medicine. This dissertation explores how these two positions come apart, why they come apart, and what we should do about it. I begin by answering the descriptive question, what are current standards of evidence in medicine? I then provide a detailed critique of these standards. Finally, I address the more difficult normative question, how should we determine standards of evidence in medicine?In medicine, standards of evidence have been established by the pervasive evidence-based medicine (EBM) movement. Until now, these standards have not been subjected to comprehensive philosophical scrutiny. I outline and defend a theory of knowledge – a version of Helen Longino’s Critical Contextual Empiricism (CCE) – which enables me to critically evaluate EBM. My version of CCE emphasizes the critical evaluation of background assumptions. In accordance with this, I identify and critically evaluate the three substantive assumptions underlying EBM. First, I argue that medicine should not be held to the restrictive definition of science assumed by proponents of EBM. Second, I argue that epidemiological evidence should not be the only “base” of medical decisions. Third, I argue that not only is the particular hierarchy of evidence assumed by EBM unjustified, but that any attempt to hierarchically rank research methods is incoherent and unjustifiably restricts medical knowledge. Current standards of evidence divert attention from many legitimate sources of evidence. This distorts medical research and practice.In the remainder of the dissertation I propose means for improving not only current standards of medical evidence but also the process of producing and defending future standards. On the basis of four CCE norms, I argue that we have reason to protect and promote those features of the medical community that facilitate diversity, transparency, and critical interaction. Only then can we ensure that the medical community retains its ability to produce evidence that is both rigorous and relevant to practice.