Two hundred years after the Copernican-Galileian revolution, a revolutionary change displaced Hippocratic-Galenic views from medicine. The essence of the revolution, prompted by conceptual changes, whose origin, mechanisms and specificity have not yet been clarified, was the transition from the nosological to the physio-pathological classifications of diseases. The medical discoveries of the last century heralded a long period of domination of the deterministic and reductionistic approaches. This domination is now weakened by the recognition that, in living organisms as well as in many diseases, evolutionary processes play a much larger role than previously thought. The mechanisms of causation during the transitions of the alterations from the lower to the higher levels of complexity cannot be satisfactorily accounted for by classical deterministic principles. The full explanation of the aetio- pathogenetic sequences and physio-pathological patterns require the concept of 'evolutionary emergence', the evolutionary generation of new information.
Among the arguments to delegitimise medicine as part of the natural sciences are the uniqueness and the historicity of medical entities and events. Natural-science medicine deals, however, with general and not individual knowledge, with phenomena belonging to classes or groups of natural events. Medicine is part of the natural sciences because it deals with objective alterations of natural processes and with the scientific method, and, like the other natural sciences, aims to understand the mechanisms underlying diseases through universal principles. In spite of the difficulties, due to insufficient knowledge of preceding conditions,complexity of living systems and occurrence of variations outside of the observable, medical predictions are not wild guesses but rational scientific anticipations. Similarly to the other natural sciences, clinical explanations aim to show that medical events are expected on the basis of conditions and covering laws.
