The historical development of the concepts of diagnosis and prognosis and their relationship to probabilistic inference.

The concepts of diagnosis and prognosis are central to the intellectual basis of modern medical practice. These concepts are rooted in philosophical ideas which were introduced by the ancient Greeks. They were also influenced by the growth of scientific understanding following the Renaissance; and the more recent discipline or probability theory. The relative importance of these histological developments are discussed and suggestions are made about the possible nature of future developments.