Isaac Levi is Dewey Professor Emeritus of Philosophy at Columbia University, where he taught since 1970. Amongst his numerous published books and articles are Gambling with Truth (1967), The Enterprise of Knowledge (1986), and The Covenant of Reason (1997).
Calvin Normore is William MacDonald Professor of Moral Philosophy at McGill University and Professor of Philosophy at the University of California Los Angeles. Some of his published articles include 'The Necessity in Deduction: Cartesian Inference and its Medieval Background' (Synthèse, 1993), 'Picking and Choosing; Anselm and Ockham on Choice' (Vivarium, 1998), and 'Some Aspects of Ockham's Logic' (The Cambridge Companion to Ockam, 1999).
Jamie Tappenden is Associate Professor of Philosophy at the University of Michigan, where he has taught since 1997. He has published on paradoxes, negation, vagueness, analytic truth, Frege's philosophy of mathematics and logic, and mathematical explanation. His current research is principally concerned with historically informed philosophy of mathematics, with special attention to shared themes in Riemann's complex analysis/algebraic geometry and the mathematical foundations developed by Frege and Dedekind.
Alasdair Urquhart is Professor Emeritus of Philosophy at the University of Toronto, having taught there since 1970. Amongst his many articles on logic, the history of logic, and computational complexity theory are: 'The undecidability of entailment and relevant implication' (Journal of Symbolic Logic, 1984), 'The number of lines in Frege proofs with substitution' (Archive for Mathematical Logic, 1997), and 'Width versus size in resolution proofs' (Theoretical Computer Science, 2007). [End Page 179]
Achille Varzi is Professor of Philosophy and Chair of the Department at Columbia University, where he has taught since 1995. Amongst his numerous published articles and books are Il mondo messo a fuoco (2010), Insurmountable Simplicities (2006), Ontologia (2005), Parole, Oggetti, Eventi (2001), An Essay in Universal Semantics (1999), Parts and Places (with R. Casati, 1999), and Holes and Other Superficialities (with R. Casati, 1994).
Stephen Yablo is Professor of Philosophy in the Department of Linguistics and Philosophy at the Massachusetts Institute of Technology, where he has taught since 1998. A number of his articles on metaphysics and mind have been collected in two books, Thoughts (2009) and Things (2010). [End Page 180]