Must We Know What We Say?

Abstract

The knowledge account of assertion seems to provide a clear and simple connection between the key concept of epistemology, knowledge, and a key concept of philosophy of language, assertion. According to the knowledge account (presented by Williamson (1996, 2000), DeRose (1996, 2002), and Unger (1975)), assertion is governed by the norm of knowledge: that we should assert only what we know. The knowledge account draws support from cases in which we judge assertion without knowledge to be impermissible, including lottery cases in particular. It is a surprising and powerful hypothesis; it takes two concepts that are defined and motivated independently and posits a strong connection between them that appears to be confirmed by linguistic data. I will argue, however, that the knowledge account cannot succeed in unifying independently important conceptions of knowledge and assertion. On the most obvious accounts of knowledge and assertion, the knowledge account is inferior to a truth account, on which the primary norm on assertion is that we should assert only what is true. The knowledge account simply gets some cases wrong, because assertion without knowledge is sometimes permissible. When we dojudge assertion without knowledge to be impermissible, that judgment can be derived from the truth norm and other norms of conversation.