Diderot is widely praised as a master of lively, dramatic and original dialogue. This book studies the developing role of dialogue in his early writings (1745 to 1754). Diderot's earlier experiments with the dialogue form, meticulously charted and analysed by D. J. Adams, opened the way to the exploration of human communication and cooperation which lies at the heart of the Encyclopédie. At first for Diderot dialogue ended in the triumph of monologue, with one speaker reducing another to silence. But one of his central problems was precisely that of solipsism. Is it possible for people to communicate effectively with each other? By engaging with this problem in his early writings Diderot gradually came to realise the epistemological importance of true dialogue as an escape from the solipsistic trap; and, slowly and hesitantly, he developed the form of communicative dialogue which was to flourish in the masterpieces of his later years.