This research aims at Jean-Jacques Rousseau and has the objective of calling attention to the way he peculiarly constructs his critique of Enlightenment from the idea that it is constituted as a historical movement whose notion of progress and improvement of the sciences, the letters and the arts enhanced even more the process of corruption initiated with man´s insertion in history. It is exactly in the first Discourse, in the Letter to D Alembert and in the Confessions that Rousseau - making use of a critical philosophy which differs from the erudite subtlety of the philosophes - explicitaly breaks with the french members of 18th century about the worst they have - the faculty of amour-propre. Although this attribute is indispensable to the life in society, the genevan objects to the exaggerated and disfigured character that it takes on among the encyclopedists, to the point of turning into the vice of hypocrisy. His preocupation in demonstrating against this vice leads to the understanding that, besides being a historically situated problem, it is also a vice against which the virtue of sincerity, innate in the human nature, is opposed to. That is why Rousseau considers himself, besides a critic of the Enlightenment, a self- critic in relation to also being, in contradiction with his inclinations, a philosophe. It is through a confessional exercise that he places in evidence an ethic of sincerity capable of revealing the natural man who is hidden behind the mask of hypocrisy. The context of the Enlightenment, as a convention and an artifice, is incapable of revealing the original identity of each human being. That is why the genevan presents himself as the responsible for idealizing the moral context that will supply it. And the idea of morality becomes expressive to the understanding of his dispute with the enlightened party. Therefore, this research also investigates how Rousseau founds in these three texts a new man and a new society from a remarkable moral guided by the dictates of a sincerely virtuous conscience.