indefiniteness

Indefiniteness is a general property describing referents that are not uniquely identified or known to the speaker or listener. It contrasts with definiteness, where a referent is assumed to be identifiable or has been previously specified in context. Indefiniteness can signal lack of specificity, non-uniqueness, or incomplete knowledge, and it arises in language, logic, and philosophy as a way to describe how speakers refer to things that are not fully determined.

In natural language, indefiniteness is typically encoded through indefinite noun phrases such as the English articles a and an in phrases like a cat, bare nouns in some languages, or through certain pronouns and quantifiers such as someone, anything, or some. Indefinite expressions often introduce a new discourse referent into the conversation, one that is not linked to a uniquely identifiable entity in the prior context. They can convey non-specific reference, generalizations, or existential readings.

Linguists distinguish several related notions. Specific indefinites refer to a particular, albeit not fully identified, entity understood from context. Non-specific indefinites lack a definite intended individual and are understood more generally, often with a wide scope over possible referents. The syntax and interpretation of indefinites can be sensitive to word order, quantifier scope, and discourse structure, influencing whether a sentence reads as having a specific, non-specific, or existential meaning.

In formal semantics, indefinites are commonly modeled using existential quantification, introducing a variable to represent an entity that is not uniquely determined. The definite description operator (iota) is used to represent definite noun phrases that imply uniqueness. Indefiniteness thus serves as a bridge between surface expression and underlying representations of reference and knowledge.

Cross-linguistic variation shows that not all languages mark indefiniteness the same way; some rely on articles, others on context, word order, or case. Beyond linguistics, indefiniteness also relates to epistemology and philosophy of language, describing indeterminacy in knowledge or future events.