Explanation
Vagueness arises when an expression has clear positive and negative cases but also borderline cases for which no completely sharp boundary of application is fixed. Terms such as tall, young, or heap remain context-dependent despite precise measurements and tolerate small changes, producing the Sorites paradox across a long sequence. Vagueness is not simply lack of knowledge: even with all facts known, category membership may remain unsettled. The conceptual movement determines comparison class and purpose, identifies clear regions and the borderline zone, and tests which theory—such as indeterminate boundaries, supervaluation, or an epistemic account—best explains the judgements.
Movement of thought
1. Clear positive and clear negative instances of the expression are collected first. 2. Comparison class, conversational purpose, and relevant dimension are made explicit. 3. Gradually changing cases expose tolerance and the emerging borderline region. 4. Ignorance of facts is separated from indeterminacy in the linguistic category. 5. Competing formal accounts are tested against judgements, inferences, and context shifts.
Scientific use case
Semantics, logic, law, and cognitive research study vagueness through Sorites series, judgements, and formal models. Applications must distinguish everyday language from legally stipulated boundaries and statistical classifications.
Example
Whether a person counts as tall for a particular group depends on comparison class and purpose. Exact height does not eliminate the borderline case unless the context supplies a binding threshold.
Counterexample
A situation is not necessarily vague when measurement data are missing. If a definite threshold has been stipulated, ignorance can be resolved by measurement; genuine vagueness concerns the category boundary itself.
Distinction
Distinguish vagueness from ambiguity with multiple readings, underdetermination of intended content, mere ignorance, and statistical uncertainty. Vagueness concerns blurred application boundaries within a meaning.
Effect on thought and perception
Vagueness makes language flexible enough for changing contexts and continuous reality. It also produces disagreement over borderline cases and enables strategic shifting of standards.
Resonance
Between an unambiguous yes and no lies a transition where language does not fully close its contours. Meaning remains mobile because the world need not provide natural cut lines.
Cite this entry
Reich, Michael (Hrsg./ed.): „Vagueness“. Atlas der Sprache, AT-134-008. ATLAS 260, data model 1.6.0. https://atlasoflanguage.com/concept/AT-134-008The address remains stable; editorial content may evolve. Editorial reading state: 2026-10-15. Include your access date for precise references.
Historical background
In III.ix.6–9 Locke attributes uncertain signification partly to complex ideas assembled differently and to the absence of shared standards. Ordinary usage can aid everyday communication while leaving substantial latitude for complex terms, especially moral designations. This historical problem connects with vagueness, but is not identical with a present theory of indeterminate category boundaries.
How conceptual history changes the analysis
Disagreement about usage, multiplicity of meanings and indeterminate boundaries should not be collapsed into one category.
References for the historical section
- John Locke, An Essay Concerning Human Understanding (first published with the date 1690), Books III–IV; Gutenberg transcription identified as based on the second edition · III.ix.4–9, doubtful signification and latitude in common use
Selected original-English passages read; not collated against first-edition page images. Modern profile labels are explicitly distinguished from the terminology used by Locke. His account of ideas is a historical philosophical position, not a verified contemporary model of language or cognition.