D’Alembert, Jean Le Rond (1717–83)

Mathematician, scientist and man of letters, Jean D’Alembert is a central figure of the French Enlightenment. As a young man he made significant contributions to the refinement of mathematical techniques, and later was actively engaged in the theoretical controversies which surrounded the gradual assimilation of Newtonian mechanics into the mainstream of European science. For twelve years (1746–58) he was co-editor, with Denis Diderot, of the Encyclopedia, the serial publication of which was one of the defining events of the Enlightenment period as a whole. D’Alembert frequented the various Paris salons where much of the intellectual fervour and high-spiritedness of the age was cultivated and given shape. As Secretary of the French Academy he worked assiduously to advance the cause of human knowledge. D’Alembert’s philosophy is characterized by an abiding commitment to the clarity and precision which attends mathematical abstraction. He believed that in its essence the natural order is internally structured by laws whose operation can be articulated under the principles of geometry. All natural phenomena are to be explained under the terms of those basic mathematical principles that govern the scientific domain in which they are located (chemistry or astronomy for example), and all scientific domains could be brought ultimately to perfect consistency and systematic order within a comprehensive theory. The events and processes which constitute the natural order reflect the reality of the mathematical structure which underlies them. As he says in the Preliminary Discourse (1751) to the Encyclopedia (1751–65), ‘The universe would only be one fact and one great truth for whoever knew how to embrace it from a single point of view’.