Illusion in Du Châtelet’s Theory of Happiness

In her Discourse on Happiness, Émilie Du Châtelet claims that one must be susceptible to illusions to be happy. She gives almost no explanation of what illusions are or what causes them, and thus the claim appears to lack an adequate defense. I offer an account of Du Châtelet’s theory of illusion by drawing upon the previously unexamined influence of other French philosophers’ accounts of the connection between passion and illusion, including Descartes, Malebranche, and Anne-Thérèse, Marquise de Lambert. According to this tradition, the passions misrepresent their objects in the imagination, and these misrepresentations can be referred to as “illusions.” Attributing this theory of passionate misrepresentation to Du Châtelet solves two puzzles about illusion that arise in the Discourse. First, it explains why she claims illusions are necessary for happiness. Second, it explains how illusions can be distinguished from cognitive errors made in other domains, like philosophy and natural science.