Definitionslücke

Definitionslücke is a term used to describe a gap or lacuna in the adequacy of a definition. It occurs when a proposed definition fails to cover all intended cases or when certain borderline cases cannot be cleanly classified by the definition. The result can be an extension that is too narrow or too broad relative to the term’s intended use, leaving phenomena undefined or misclassified.

The concept is used in philosophy of language, logic, linguistics, and law to critique definitions that are assumed to be sufficient for a term’s purpose. It is related to, but distinct from, vagueness and boundary problems, and it highlights tensions between extension (what falls under a term) and intension (the criteria that determine belonging).

Examples are typically hypothetical or domain-specific. A legal definition of “gefährlich” (dangerous) that hinges on physical injury may miss digital or systemic threats. A normative term like “gerecht” (just) can vary with context, creating a definitionslücke in ethical or political discourse. In science, terms such as “Spezies” may encounter definitional gaps at border cases like ring species, where clear categorization is problematic.

Addressing a definitionslücke often involves revising the definition to be more inclusive or context-sensitive, using disjunctive or multi-criteria criteria, or adopting a prototype or graded membership approach. In legal or policy contexts, supplementary criteria or open-ended lists can help mitigate gaps.

In scholarly discussions, recognizing a definitionslücke helps refine terminology, improve interpretive clarity, and prevent misapplication by making explicit the limits of a given definition.