 Arnauld was an important participant in the philosophical debates of his century, and carried out famous intellectual exchanges with Descartes, Malebranche, and Leibniz. In addition, the Port-Royal Logic, l’Art de penser, which he co-authored with Pierre Nicole, was a standard text in the field for two centuries. Less attention has been paid to Arnauld’s lifelong efforts to reconcile the doctrine of grâce efficace par elle-même with freedom of will, though they have many connections with the debate about determinism and free will that continues to this day.