This dissertation is a study of the materialist current of the French Enlightenment. Far from assuming that early modern materialism constituted a homogenous philosophical current, my dissertation applies the materialist method of critique to the category of "materialism" itself. I argue that "Materialism" was invented in the 18th century, and it had little to do with the simple affirmation of the primacy of matter or the reductionist "one -substance monism", as its detractors at the time wanted the public to believe. I show that the adjective "materialist" was coined in the context of a social transformation of philosophy (a social reconfiguration of philosophical activity with the rise of the bourgeois public sphere) and in the midst of an ideological crisis of French absolutism. I argue that religious and political authorities labeled a set of public philosophical interventions that advocated for a new conception of public philosophy, an experimental and critical one, as "materialists". Most of the thinkers which were labeled as materialists (Julien Offray La Mettrie, Denis Diderot, Claude-Hadrien Helvetius, Paul Henry Thiry D'Holbach) borrowed from the emerging field of modern science a critical method of inquiry, yet, what distinguished them particularly was that they extended this critique to moral values, metaphysical concepts and the political institutions of the regime. They also shared a commitment to an intellectual political independence from the State and to the development of the critical function of philosophy in an expanded public sphere. It was for this reason that materialism was considered morally and politically "dangerous" as a philosophy, one that needed to be repressed and persecuted. By the early 19th Century with the re-institutionalization of philosophy by the Empire materialism as a public philosophical critique was dead.
After 1758 the debate around materialism polarized the Enlightenment movement itself. Some of the key figures of the Enlightenment, like Voltaire, Jean e Rond D'Alembert or Nicolas Condorcet, which had secured for them a place in the French academy, began to distance themselves from the materialist figures and from their public positions, by defending publicly the benefits of an "enlightened monarchy" and a necessary metaphysical base for science, philosophy and morality.
In my dissertation I argue that the "radical" and "political" dimension of La Mettrie's and Diderot's philosophy is not to be found in the proposal of a positive program of reform. Theirs was an exploration of the new public status of philosophy and the philosophical means to achieve a popular enlightenment. Besides being the first advocates for a public education system open to all and targeted to a diversity of social needs, they reflected on the form philosophical texts should produce. Philosophical form, for La Mettrie and Diderot had to necessarily appeal not only to reason but also to imagination, using fiction, and requesting from the reader an active and open interpretation in order to "enlighten" him or her in a non-deterministic way.