The diversification of scientific knowledge is increasing rapidly as more and more aspects of the material universe and more and more forms of human activity are being investigated in greater and greater depth, within the framework of increasingly rigorous theory building. Fields of specialization (pure and applied sciences, natural and social sciences) now number in the order of a thousand. Interdisciplinarity thus becomes a highly complex process involving a very large number of specialists from essentially different disciplines, and this complexity accentuates the difficult problem of communication which is thus posed. The fragmentation inherent in the growth process will increasingly affect the ability to tackle development problems, for the solution of which will be required an entirely new type of scientist, trained in the methods of global analysis and able to identify the problems and to select techniques by which they can be solved.