  More generally, one might question whether the objection still has much bite once the metaphors of “accessing” and “comparing” are spelled out with more attention to the psychological details of belief formation and to epistemological issues concerning the conditions under which beliefs are justified or warranted. For example, it is quite unclear how the metaphor of “comparing” applies to knowledge gained through perceptual belief-formation. A perceptual belief that p may be true, and by having acquired that belief, one may have come to know that p, without having “compared” (the content of) one’s belief with anything.