Following Dorst (2026), this paper develops a higher-order account of epistemic vagueness. I begin by reconstructing Williamson’s epistemicist account of vagueness, focusing on the margin principle. I argue that epistemic vagueness cannot be explained by first-order indiscriminability alone, since such an explanation is self-undermining. A satisfactory account therefore appeals to higher-order uncertainty. I then clarify that the margin principle rests on two assumptions: the indiscriminability of just-noticeable differences (JNDs) and gradualness. I suggest that the former must be restricted, while the latter is incompatible with empirical data and unnatural. Finally, I argue that higher-order uncertainty provides a better explanation of non-gradual patterns in epistemic vagueness, and that this explanation is supported by psychological studies on discrimination and metacognition.
