Should You Defer to Individual Experts?

Should you defer to individual experts? That is, when a single expert—rather than a group of experts or a expert consensus—testifies that p, should you believe that p? In this paper, I argue that the answer to this question is, generally speaking, “no.” My argument is based on the notion of a complexity‐based defeater. Some questions are complex in a sense that makes inquirers less reliable at answering them. Expert testimony tends to be about such questions. Expert testimony thus tends to be subject to a complexity‐based defeater. The pressing question, then, is whether the speaker's expertise in turn defeats that complexity‐based defeater. I first draw on the extant literature to show why we cannot reliably make case‐by‐case determinations of whether a particular speaker's expertise counteracts the complexity of the particular question they are answering. Next, I argue that a speaker's status as an expert does not, in general, defeat the complexity‐based defeaters that tend to come with expert testimony. We thus should not, generally speaking, defer to individual experts. I then address some issues with the peer review system that are relevant to the core argument. Finally, I briefly discuss a path to rational deference that remains open: a path through expert judgment aggregation.