Presupposition

A presupposition is information an utterance treats as background that is taken for granted, surviving under negation and questioning.

Definition

A presupposition is a proposition whose truth an utterance takes for granted; it characteristically remains constant when the utterance is negated or questioned.

Scope

This topic covers the nature of presupposition, the lexical and constructional items that trigger it (definite descriptions, factive verbs, aspectual verbs, clefts, and others), and its defining diagnostic of constancy under negation. It treats the contrast between semantic accounts, on which presupposition yields a truth-value gap when it fails, and pragmatic accounts, on which presupposing is treating a proposition as common ground.

Core questions

• What does it mean for an utterance to presuppose a proposition?
• Which expressions trigger presuppositions?
• Why do presuppositions survive under negation?
• Is presupposition fundamentally semantic or pragmatic?

Key concepts

• presupposition trigger
• constancy under negation
• factive verbs
• truth-value gap
• common ground
• presupposition failure

Key theories

Semantic presupposition and truth-value gaps (Strawson)

An expression like a definite description presupposes the existence of its referent, so when the presupposition fails the sentence is neither true nor false, contrary to Russell's analysis.

Pragmatic presupposition (Stalnaker)

Presupposition is a relation between a speaker and a proposition: to presuppose is to treat the proposition as part of the common ground, shifting the phenomenon from sentence semantics to speaker behaviour in context.

History

Strawson's 1950 critique of Russell introduced presupposition to the philosophy of language via referring expressions. In the 1970s presupposition became a major topic of linguistic pragmatics, with semantic accounts using truth-value gaps and Stalnaker's pragmatic account framing presupposition in terms of the common ground, a contrast that still organizes the field.

Debates

Russellian quantification vs. Strawsonian presupposition

Whether sentences with empty definite descriptions are false (Russell) or lack a truth value because a presupposition fails (Strawson), with broad consequences for the analysis of reference.

Key figures

• P. F. Strawson
• Robert Stalnaker
• Lauri Karttunen

Seminal works

• strawson1950
• stalnaker1974

Frequently asked questions

Why is constancy under negation a test for presupposition?

Because a presupposition is preserved when the main assertion is negated: both 'John stopped smoking' and 'John didn't stop smoking' presuppose that John used to smoke, which distinguishes the presupposed background from the asserted content.