A semantic theory of vagueness that holds that vague predicates in fact have precise, sharp boundaries or extensions, but that those boundaries are epistemically inaccessible to speakers; vagueness is therefore a matter of ignorance about exact cutoffs rather than semantic indeterminacy.

Principle

If epistemicism is true, every borderline case has a determinate status (P or not‑P), and classical bivalence and standard logical laws remain valid even though speakers cannot identify the boundary.

Demonstration

Illustrative scenario — Situation: There exists an exact height h such that everyone equal to or above h is 'tall' and everyone below is not. Recognition: Speakers cannot know h. Action: Faced with a borderline individual, an assessor admits ignorance. Consequence: Semantically the individual is determinately tall or not, but the assessor lacks the means to establish which.

Misapplication

Conflating epistemicism with mere practical indistinguishability or claiming it dissolves all problems of vagueness in practice; the error is to treat ‘‘unknowable sharp boundary’’ as implying ‘‘no substantive theoretical differences’’ rather than recognizing it preserves classical semantic commitments while relocating difficulty to knowability.

Consequence

Epistemicism preserves classical logic and bivalence, so paradoxes like sorites are explained by unknown cutoffs; the theory shifts the explanatory burden from semantic indeterminacy to a metaphysical or semantic thesis about determinate but unknowable boundaries.

Reversal

Epistemicism does not hold in semantic frameworks that treat vagueness as genuine indeterminacy (e.g., supervaluationism or degree semantics) or in contexts where meanings are explicitly context‑sensitive and lack fixed extensions.

Boundary

Applies to debates about the semantics of vague predicates in philosophy of language; it does not by itself supply empirical evidence about where cutoffs lie, nor does it claim that speakers can, in practice, find the boundaries.

Semantic Tension

Preservation of bivalence and classical logic ↔ Intuitions of semantic indeterminacy and the need for graded or indeterminate semantics; epistemicism trades the latter for epistemic inaccessibility.

Synthesis

Epistemicism reframes vagueness as a problem of unknowable exactitude: it retains classical semantics at the cost of positing determinate boundaries that, though metaphysically present, are practically and epistemically out of reach.