This is the first full-length study of Antoine Arnauld, one of the most important thinkers of the seventeenth century. It examines both Arnauld's commitment to the methodological and metaphysical principles of Descartes and his own contributions to the metaphysics and epistemology of perception and knowledge. In particular, it scrutinizes the celebrated debate between Arnauld and Nicolas Malebranche, in which Arnauld argued for a view of ideas as mental acts, against Malebranche's view of them as objects in the divine intellect. Questioning a popular view of Descartes and the Cartesians posited in the mid-eighteenth century by Thomas Reid and most recently developed by Richard Rorty, Steven Nadler argues that Arnauld's "act theory" faithfully interprets Descartes and provides a foundation for a direct realist theory of perception. Moreover, Nadler argues, Arnauld's understanding of the representative character/objective reality of ideas provides for a sophisticated explanation of the intentionality of mental acts.


Descartes and his followers have been criticized for a belief that the mind can have only its own ideas as immediate objects of perceptions, rather than being able directly to perceive objects in the external world. Nadler, on the other hand, contends that such criticisms are misreadings of both Descartes and the development of early modern epistemology. Throughout the book, Nadler pays careful attention to the historical and religious context of Arnauld's work, particularly to his Jansenist commitments and the more important theological motivations for his debate with Malebranche.