Unpossessed evidence revisited: our options are limited

Several influential thought experiments from Harman 1973 purport to show that unpossessed evidence can undermine knowledge. Recently, some epistemologists have appealed to these thought experiments in defense of a logically stronger thesis: unpossessed evidence can defeat justification. But these appeals fail to appreciate that Harman himself thought of his examples as Gettier cases, and so would have rejected this strengthening of his thesis. On the contrary, he would have held that while unpossessed evidence can undermine knowledge, it leaves justification intact. In this paper I seek to undermine the viability of Harman’s position. If this is correct, contemporary epistemology faces a choice: either we reject that unpossessed evidence in Harman-style cases bears on knowledge at all, or else we must allow that it undermines knowledge by defeating justification. The former option must explain why Harman’s thought experiments elicit strong ‘no knowledge’ intuitions; the latter option embraces a minority view about the bearing of social expectations on the assessment of knowledge and justification (= the doctrine of normative defeat).