This study attempts to establish the public relevance of Cartesian philosophy. An older lineage of French theorists, including D'Alembert, Guizot, and Tocqueville, considered the philosophy of René Descartes to have had an explosive impact upon the intellectual, political, and social climates of the seventeenth, eighteenth, and nineteenth centuries. Most Descartes scholarship in the intervening centuries has not pursued this line of thought. In agreement with the aforementioned theorists that Descartes is a politically relevant philosopher despite having no political philosophy, this study nevertheless departs from their accounts on key grounds. Whereas the French theorists were primarily interested in the social effects of Cartesian philosophy, that is, the reduction of the authority of Aristotle and the Catholic Church, this study takes as its starting point the question of Descartes's own intentions in publishing his philosophy in the forms he chose. In the last part of his first publication, the Discourse on Method (1637), Descartes draws attention to the fact that he need not have published anything at all, since publication would likely disrupt his own life and activities as a philosopher. Descartes's decision to publish his philosophical principles is therefore an important indication of the intended public relevance of his philosophy.This study consists of an inquiry into the deficiencies of the philosophical tradition according to Descartes and a presentation of the Cartesian resolution of these deficiencies through the method. Many contemporary scholars, especially in the Anglosphere, have argued against the significance of Descartes's method on grounds that it was not historically useful for spurring specific discoveries in natural philosophy or science. Against these scholars, I posit that Descartes intended his method to correct for the main deficiency of ancient and scholastic philosophy, which he identifies as the inclusion of probable conjectures (specifically sense perceptions) in the formation of judgments and the consequent inability of traditional philosophy to discover certain knowledge and propagate it to the public. Furthermore, I argue that Descartes intended the practice of his method to habituate the mind to new habits of thinking. On this point, I attempt to establish the significance of Descartes having publicly introduced his method for the first time through a comparison to the act of legislating. Altogether, I argue, the method is intended to enable the discovery of certain knowledge on the level of the individual and to make known the worth of philosophy to the public.