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).

Harman 1973 年发表的几个有影响力的思想实验旨在表明，未掌握的证据会破坏知识。最近，一些认识论者诉诸这些思想实验来捍卫一个逻辑上更强大的论点：没有证据可以击败正当性。但这些上诉没有认识到，哈曼本人将他的例子视为盖蒂尔案例，因此会拒绝对他的论点的这种强化。相反，他会认为，虽然没有证据会破坏知识，但它会使正当性完好无损。在本文中，我试图削弱 Harman 立场的可行性。如果这是正确的，那么当代认识论就面临着一个选择：要么我们拒绝哈曼式案例中未掌握的证据与知识有任何关系，要么我们必须允许它通过击败正当性来破坏知识。前一种选择必须解释为什么哈曼的思想实验会引发强烈的“无知识”直觉;后一种选择包含了少数人的观点，即社会期望对知识和正当性评估的影响（= 规范性失败的学说）。