Abstract

An epistemic trespasser is someone who lacks expertise in a domain yet expresses an opinion about its subject matter based on their own assessment of the evidence. Epistemic trespassing is prima facie problematic, but philosophers have argued that it is appropriate when the trespasser possesses relevant skills and evidence. We argue that this defence is available to epistemic trespassers more often than most philosophers have recognized, but it does not vindicate trespassing. The justified trespasser must also possess an appropriately refined sense of how and to whom they ought to defer, with ‘deference’ understood as taking opinions and the shape of debates very seriously in deliberation, and as appropriate caution in dissent. This sense of what we call the guardrails is constituted largely by a kind of know-how, which arises from long experience in a domain: the epistemic trespasser almost always lacks this know-how.