witnesswhether

Witnesswhether is a term used in formal semantics and philosophy of language to denote an operator that encodes the act of producing a witness for the truth value of a proposition. The idea is to model how a statement’s truth can be settled not merely by asserting it, but by providing concrete evidence that supports its truth or its negation.

Formally, the operator is described as a mechanism that, given a proposition p, engages the process of obtaining a witness for p or, alternatively, a witness for not p. In constructive or game-theoretic semantics, this can be represented as a requirement that a witness exist for p (certifying p) or a witness exist for ¬p (certifying its negation). The resulting discourse focuses on evidential grounds rather than on truth conditions alone.

Witnesswhether is distinct from existential quantification, which seeks an object that makes a predicate true, because it centers on the availability of evidence about the proposition’s truth value rather than on the existence of a particular object satisfying a predicate. It is related to evidentiality in linguistics and to proof-theoretic and game-semantics frameworks, where the legitimacy of a claim depends on obtaining appropriate support.

Examples are often hypothetical. For instance, in discussing the proposition “The sensor indicates a fault,” a witnesswhether construction would consider whether there exists a verifiable witness (such as a diagnostic report) that confirms p or, alternatively, a witness that confirms ¬p. The concept remains primarily theoretical and is not widely standardized across literature, though it has been used to explore how evidence and witnesses shape the assessment of truth in discourse.

See also: witness, evidence, evidentiality, constructive logic, game semantics.