Eric T. Olson has a special interest in the metaphysical nature of human beings. He is the author of two other books: The Human Animal: Personal Identity Without Psychology (1997) and What Are We? A Study in Personal Ontology (2007). Aaron Segal is the Michael and Bella Guggenheim Senior Lecturer in Philosophy at The Hebrew University of Jerusalem, and he has published widely in metaphysics, philosophy of religion, and analytic Jewish philosophy.