Peter van Inwagen is the John Cardinal O'Hara Professor of Philosophy at the University of Notre Dame, Indiana. He is the author of An Essay on Free Will (1983), and his numerous other publications include Material Beings (1990), Ontology, Identity, and Modality: Essays in Metaphysics (Cambridge, 2002), The Problem of Evil (2006), and Existence: Essays in Ontology (Cambridge, 2014).