 Stern advances a conception of this kind of argument on which it addresses a skeptic who questions whether certain beliefs cohere with others in one’s set, as opposed to a skeptic who questions whether certain beliefs are true (Stern 1999). A modest transcendental argument would then aim to show that a belief whose coherence with the other beliefs is challenged so coheres after all. The requisite coherence might be demonstrated by showing that the belief in question is actually a necessary condition of a belief that is indispensable (in some coherentist sense) to one’s set. Mark Sacks (1999) objects that if at the same time one were to admit that the belief might not be true, one’s sense that one is justified in holding the belief would be undermined. This worry is a serious one. Sacks argues that it arises because of a tension between the coherentist theory of justification and the realist correspondence theory of truth that the external world skeptic presupposes. One might respond, he points out, by accepting a coherence theory of truth as well, but this would be to adopt a version of idealism. Moreover, it seems that Sacks’s proposal would not solve the problem, for the reason that even if one accepted a coherence theory of truth, one would still have to admit that for specific instances of a belief one might be mistaken, even if one maintained that one was justified in holding that belief on grounds of coherence.