ABSTRACT
This chapter considers the types of evidence which can be used to confirm, or disconfirm, a causal hypothesis in medicine. Robert Koch's postulates were designed to give evidential criteria, which, if satisfied, would establish causal hypotheses of the form: such and such a microbe causes disease. Robert Koch produced evidence which not only confirmed his own theory of cholera and led to its general acceptance, but also disconfirmed Max von Pettenkofer's alternative theory of cholera and led to its rejection. Although the case of establishing a causal hypothesis in medicine is very important, and attracts a lot of attention, the more Popperian case of evidence disconfirming a hypothesis, and perhaps leading to the hypothesis being rejected by the medical community, should not be forgotten. To illustrate the distinction between statistical evidence and evidence of mechanism, the chapter provides some examples from the study of coronary heart disease (CHD).
