Is There a Real Difference Between Undercutting and Rebutting?

ABSTRACT

Defeaters in epistemology are the things that make justified beliefs lose their justification. Philosophers distinguish between different kinds of defeaters, and one such distinction is commonly made between rebutting and undercutting defeaters. That this distinction is both tenable and important has been orthodoxy ever since Pollock introduced it more than half a century ago. This article challenges the orthodoxy. I argue that, taken together, Pollock's definitions and the assumptions made by subsequent literature imply one of two things: Either every defeater is both rebutting and undercutting, which means that there is no material distinction between the two, or else the distinction turns out to be arbitrary, yielding counterintuitive implications and lacking the significance attributed to it.