Suppose sentence U is such that relevant experts currently have no effective procedure for determining whether what the sentence expresses is true or false. Semantic realism is the thesis that understanding U consists in grasping U's truth-conditions, and these conditions may obtain or not regardless of whether relevant experts are in principle able to recognize it. Semantic anti-realists agree that understanding U consists in grasping U's truth-conditions, but claims these truth-conditions are constrained by speaker evidence. Why accept this latter thesis over realism? Consider the following so-called Manifestation Argument against semantic realism a central tenet of which if found in the supposition in line (1):

(1)   SUPPOSE: U has evidence-transcendent truth-conditions
(2)  Relevant experts understand U
(3)  If speaker S understands sentence P then S grasps P’s truth-conditions
(4)  Hence, relevant experts grasp U’s truth-conditions
(5)  If S grasps P’s truth-conditions, this manifests in S’s use of P
(6)  Hence, experts manifest grasp of U’s truth-conditions in use of U
(7)  Hence, relevant experts manifest grasp of U’s evidence-transcendent truth-conditions in use of U
(8)  It is not the case relevant experts manifest grasp of U’s evidence-transcendent truth-conditions in use of U
(9)  Hence, U does not have evidence-transcendent truth-conditions

Since (9) conflicts with semantic realism, if the argument is sound this thesis is false. Come explore whether it is sound or not, as well as the delicate dialectic between realists and anti-realists in a paper I'm working on here!