 Poulain’s thought was deeply influenced by René Descartes’ philosophy. He used Descartes’ methods of doubt and right reasoning in order to reject prejudices about the inferiority of women and his arguments in defense of the equality of the sexes use many insights drawn from Descartes’ account of the nature of the human being. After an introductory biographical sketch, this entry will first examine the Cartesian foundations of Poulain’s thought and then proceed to a discussion of his analysis of the subjugation of women. Next, his four main arguments for the equality of the sexes are presented and evaluated. The entry closes with a brief discussion of Poulain’s direct and indirect relations to later developments in the history of feminist thought. Throughout, the aim is to present Poulain’s core ideas as well as examine their philosophical validity.