Public and private hypotheses.

Abstract

The uses of hypothesis in scientific medicine and in clinical medicine are broadly similar; but they differ in subtle but important logical details. The key distinction is that scientific medicine deals with broad ("public") hypotheses about entire populations; and the predominant problem of inference is statistics in the face of epistemological uncertainty. In contrast, clinical medicine deals with individual, tailor-made ("private") hypotheses; the uncertainty (e.g. the diagnosis or recurrence risk in relatives) is ontological, and the main feature of the analysis is probability. The same logical rules are at times mistakenly applied to both. Disregard of these subtleties may lead to paradoxes, contradictions, and at times diastrously false conclusion. The basic principles and distinctions are laid out with illustrations that are most readily provided from medical genetics, but apply to all branches of medicine.