##  [Borderline Case](/borderline-case-0) 

 Definition

An object, event, or instance for which it is indeterminate—under a specified interpretation of a vague predicate—whether the predicate applies; such instances lie on the margin of the predicate’s extension where no sharp truth‑value assignment is mandated by ordinary usage.

 

 

 

 

 

 





## Principle

Principle

If a predicate is genuinely vague within a given interpretive frame, then there will exist instances for which the predicate’s application is not determinately true or false under that frame.

 

 

 

 

 





## Demonstration

Demonstration

Illustrative scenario → A committee must award the label “tall” in a context without a fixed threshold. A person of height 1.70 m yields disagreement among competent judges: some apply the predicate, others do not. Recognition: the committee identifies the case as marginal. Action: they either adopt an explicit cutoff for decisions or treat it case‑by‑case. Consequence: without an imposed rule, different competent speakers rightly disagree about application.

 

 

 

 

## Misapplication

Misapplication

Treating a borderline case as merely an epistemic lack of information (i.e., that a determinate fact exists but is unknown) rather than as semantic indeterminacy. The error confuses limited evidence with lack of determinacy in the predicate's extension under the chosen interpretation.

 

 

 

 

 





## Consequence

Consequence

Practical decisions that depend on the predicate require either an explicit convention (thresholds, measurement rules) or acceptance of indeterminacy; failure to do so produces inconsistent classifications, regulatory uncertainty, or ad hoc decision‑making.

 

 

 

 

## Reversal

Reversal

When the predicate is given a precise operational definition, measurement protocol, or legal threshold within the relevant context, previously borderline cases are resolved and cease to be indeterminate.

 

 

 

 

 





## Boundary

Boundary

Clearly within: an object whose properties satisfy an established, contextual standard for the predicate (e.g., a person with no hair regarded as bald under ordinary usage). Boundary case: a person losing hair gradually where ordinary usage yields persistent disagreement about “bald.” Clearly outside: an object that manifestly fails the predicate’s central criteria (e.g., a person with a full head of hair is not bald).

 

 

 

 

 





## Semantic Tension

Semantic Tension

Precision (the desire for unambiguous classification) ↔ Communicative flexibility (the utility of vague predicates for broad, context‑sensitive application).

 

 

 

 

 





## Synthesis

Synthesis

Borderline cases show that some applications of language resist determinate classification unless external conventions or decisions are introduced; resolving them is therefore as much a pragmatic or normative choice as a semantic one.