It is generally agreed that Rousseau affected a pessimistic posture toward modernity and that this posture resulted from his failure to deal with the problems of modern industrial society. Underlying this failure, I would like to suggest, is a contradiction between Rousseau's economic ideas, i.e., his defense of private property, and his political ones, i.e., his call for the creation of a communal society in which freedom would be realized through obedience to the general will.
In a society based on private property, as Rousseau had to admit, an inevitable conflict exists between private economic interests and the general interest of society. In order to minimize that conflict, so that the general will would have a chance to prevail, Rousseau advocated a return to a simple society based on a primitive economy. This, however, was bound to be a short-lived solution, because, as he very well knew, the forces of economic development could not be arrested, and the appearance of a full-blown competitive economy could not be long delayed. Thus, Rousseau's clear insight into the problems of an emerging bourgeois society, coupled with his inability to find a way of alleviating these problems, constituted the root causes of his pessimism.