Some Remarks on Bonjour on Warrant, Proper Function, and Defeasibility


  • Colin Ruloff The Claremont Graduate School



A number of counterexamples have recently been leveled against Alvin Plantinga's Proper Functionalism, counterexamples aimed at showing that Plantinga's theory fails to provide sufficient conditions for warrant — that elusive epistemic property which together with true belief yields knowledge. Among these counterexamples, Laurence Bonjour's is perhaps the most formidable and, if successful, shows that Proper Functionalism is simply too weak to serve as an acceptable theory of warrant. In this paper, I argue that, contrary to initial appearances, BonJour's counterexample is not successful. More exactly, I argue that, once it is recognized that a defeasibility constraint is deeply embedded within Plantinga's proper function condition for warrant — a constraint which says, in effect, that a belief B is warranted for an agent S only if S does not possess any defeaters against B — BonJour's counterexample to Proper Functionalism can be handled quite straightforwardly.

Author Biography

Colin Ruloff, The Claremont Graduate School

Colin P. Ruloff, Ph.D. earned a B.A. (Hons.) from Simon Fraser University, and an M.A. and Ph.D. from the Claremont Graduate School in Claremont, California. His research interests lie primarily in epistemology and analytic philosophy of religion, and his publications include “Some Remarks on BonJour on Warrant, Proper Function, and Defeasibility” (in Principia: An International Journal of Epistemology, 2000), “Evidentialism, Warrant, and the Division of Epistemic Labor” (in Philosophia: The Philosophical Quarterly of Israel, 2003), and “Plantinga’s S5 Modal Argument, Obvious Entailment and Circularity: Response to Sennett (in Philo: The Journal of the Society of Humanist Philosophers, 2004). He also has published a number of book reviews. When not doing philosophy, Colin enjoys surfing and skateboarding, both of which he has done competitively.