[From aphorism to paradigm - on the development of the randomized clinical trial]

This article focuses on the development and acceptance of the randomized clinical trail (RCT). The emphasis is on the Kuhnian notion of exemplars known as "past scientific achievements" as guidance for paradigmatic research. Three past scientific achievements are introduced belonging to different historical periods. The numerical method was introduced in 1839 in Denmark, but the method was met with strong scepticism, and thus the method did not develop very far. In 1898 a Danish physician, Fibiger, used the statistical method in a clinical investigation studying diphtheria antitoxin. However, the statistical method did not have any remarkable impact on the practicing physicians around the turn of the century. In 1948 the British Medical Research Council published a study on streptomycin using a research design known today as the randomized clinical trial. This study has received a lot of attention and has become "the paradigm" in evaluating therapies. From a Kuhnian perspective, the path leading to the randomized clinical trial has been rather long as it is possible to identify past scientific achievements (or exemplars) leading to the randomized clinical trial belonging to the nineteenth century. Hence, the basic elements in RCT has been known for more than hundred years, but the RCT did not come alive until this century. Different explanations are suggested in order to explain why the RCT "arrived so late", namely the discussion of scientific authority, the conflict between personal acquired knowledge versus universal scientific knowledge and different divergent concepts of disease.