Thomas Grundmann

Undoubtedly, the testimony of scientific experts carries significant epistemic weight. But how exactly does it normatively constrain the belief formation of laypeople? This book argues that expert testimony holds epistemic authority over laypeople in a way that partly preempts their critical reasoning from being rationally usable in belief formation. This Preemption View of epistemic authority, shaped by philosophers such as Joseph Raz, Arnon Keren, and Linda Zagzebski, has yet to receive a thorough epistemological explanation, a compelling motivation, or a robust defense against challenges—all of which this book aims to provide. Preemptive reasons are explored through the framework of higher-order defeat, with a novel argument demonstrating how expert testimony generates these higher-order defeaters. Because these defeaters are themselves defeasible and of limited scope, the book systematically addresses and overcomes the ten most significant objections to the Preemption View. The emerging view explains how laypeople’s deference to experts is properly linked to their thinking for themselves and what remains of their epistemic autonomy. Additionally, the book offers a short history of epistemic authority and applies its theoretical insights to real-world phenomena.

Contemporary epistemologists typically define a priori justification as justification that is independent of sense experience. However, sense experience plays at least some role in the production of many paradigm cases of a priori justified belief. This raises the question of when experience is epistemically relevant to the justificatory status of the belief that is based on it. In this paper, I will outline the answers that can be given by the two currently dominant accounts of justification, i.e. evidentialism and reliabilism. While for the evidentialist, experience is epistemically relevant only if it is used as evidence, the reliabilist requires that the reliability of the relevant process depends on the reliability of experiential processes. I will argue that the reliabilist account accommodates our pre-theoretic classifications much better. In the final part of my paper I will use the reliabilist criterion to defend the a priori—a posteriori distinction against recent challenges by Hawthorne and Williamson