This paper introduces taxonomy of clinical uncertaintes and argues that the choice of scientific method should match the underlying level of uncertainty. Clinical trial is one of these methods aiming to resolve clinical uncertainties. Whenever possible these uncertainties should be quantified.

The paper further shows that the still ongoing debate about the usage of “equipoise” vs. “uncertainty principle” vs. “indifference” as an entry criterion to clinical trials actually refers to the question “whose uncertainty counts”. This question is intimately linked to the control of research agenda, which is not quantifiable and hence is not solvable to equal acceptability to all interested parties. The author finally shows that there is a predictable relation between [acknowledgement of] uncertainty (the moral principle) on which trials are based and the ultimate outcomes of clinical trials. That is, [acknowledgement of] uncertainty determines a pattern of success in medicine and drives clinical discoveries.