Evidence-Based Medicine is a relatively new movement that seeks to put clinical medicine on a firmer scientific footing. I take it as uncontroversial that medical practice should be based on best evidence – the interesting questions concern the details. This paper tries to move towards a coherent and unified account of best evidence in medicine, by in particular exploring the EBM position on RCTs (randomised
controlled trials) in assessing causal claims from clinical medicine (especially of course concerning the efficacy of various drug therapies).
I argue that even the qualified endorsement of RCTs that a more detailed and sympathetic reading of the EBM literature provides is not clearly based on solid epistemological grounds. I do this by examining four arguments that have been given that claim to show the special ’validity’ of data obtained from RCTs. Finally, I discuss a case (involving a new treatment ECMO for neonates suffering from a particular condition) that shows how closely intertwined are ethical judgments and epistemological judgments about the power of certain types of trial.