[Scientific languages and the science of complexity]

For centuries the goal of galileian and newtonian science has been the discovery of the universal laws of nature governing all natural phenomena. But, starting with the sixties of this century, advanced research has concentrated on the study of the characteristic aspects of irregular and unrepeatable evolutionary processes. Signs of this change are the rediscovery of Poincaré's results on the dynamics of non linear systems, and the extraordinary development of evolutionary thinking. Three properties characterize complex systems: the multiplicity of their levels of organization, the presence of self-referential loops of internal communication, and the irreducible nature of their past history to structural properties. The traditional cartesian gap between mind and body therefore falls down, as argued at length by the works of Gregory Bateson. His arguments are further strengthened by the neurologist Antonio Damasio in his book on reason, emotion and human brain, whose title is L'errore di Cartesio (The error of Descartes), where the negative consequences of this error on the development of science in general and on contemporary medicine in particular, are illustrated.