ABSTRACT
The view of reason and understanding as the reduction of differences to identity is not shared by certain more recent philosophers, notably M.Gaston Bachelard and M.MorotSir. I shall take, to illustrate the thought of these two men, Le Nouvel Esprit scientifique and La Philosophie du non of M.Bachelard, and La Pensée négative of M.Morot-Sir. What the assimilationists like Lalande and Meyerson wanted to show was that rational thought seeks more and more general resemblances between things and systems of things, and extends the field of human knowledge and power by this means. M.Bachelard stresses the discontinuity in rational and scientific thought which is brought about by the periodic bankruptcy, from the point of view of further progress, of a coherent rational system, and its replacement by a new model, involving a new synthesis. So scientific advance does not depend on any gradual and continuous process of the elimination of diversity, through the action of a mental substance which is simple in nature and tends to impose its homogeneity on its environment. On the contrary the world is seen as stubbornly plural, so that any synthesis is of limited validity, not only in space but in time too, since a constant discarding of useless moulds is necessary in the face of new difficulties which arise.
