Norms of Assertion: The Quantity and Quality of Epistemic Support

We show that the contemporary debate surrounding the question “What is the norm of assertion?” presupposes what we call the quantitative view, i.e. the view that this question is best answered by determining how much epistemic support is required to warrant assertion. We consider what Jennifer Lackey (2010) has called cases of isolated second-hand knowledge and show—beyond what Lackey has suggested herself—that these cases are best understood as ones where a certain type of understanding, rather than knowledge, constitutes the required epistemic credential to warrant assertion. If we are right that understanding (and not just knowledge) is the epistemic norm for a restricted class of assertions, then this straightforwardly undercuts not only the widely supposed quantitative view, but also a more general presupposition concerning the universalisability of some norm governing assertion—the presumption (almost entirely unchallenged since Williamson’s 1996 paper) that any epistemic norm that governs some assertions should govern assertions—as a class of speech act—uniformly.