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Relevance theory proposes that utterance interpretation is driven by search for optimal relevance: listeners assume speakers provide information maximizing cognitive benefit relative to processing effort. This framework explains inferential implicatures and how context guides interpretation.
Apply Relevance Theory to resolve ambiguities and infer implicatures in real discourse; compare relevance-theoretic explanations with Gricean maxims for cases of divergence.
Relevance is not subjective preference; it is a technical property of relative cognitive effect to processing cost, formally defined by Relevance Theory.
You already know Grice's theory of conversational implicature: speakers generate meaning beyond what is literally said, and listeners recover this meaning by assuming the speaker is following the Cooperative Principle and its maxims (quantity, quality, relation, manner). Relevance Theory, developed by Dan Sperber and Deirdre Wilson in the 1980s, keeps Grice's core insight — that communication is inferential — but replaces his four maxims with a single, more fundamental principle. The claim is that human cognition is oriented toward relevance: we preferentially process information that yields the greatest cognitive benefit for the least mental effort. Communication works because speakers know this about listeners, and listeners know that speakers know it.
The technical definition is precise. Cognitive effects are changes to a listener's mental representation of the world: a stimulus has cognitive effects if it combines with existing knowledge to yield new conclusions, or if it strengthens or weakens existing assumptions. Processing effort is the mental work required to parse an utterance, access context, and compute an interpretation. Relevance is the ratio of cognitive effects to processing effort — greater effects for less effort means higher relevance. The Principle of Optimal Relevance states that every utterance is interpreted as achieving the greatest relevance the speaker could reasonably achieve, given the speaker's abilities and preferences. This is not a rule speakers consciously follow; it is a description of how the cognitive system operates automatically.
Consider why this improves on Grice. Grice's maxim of Relation ("be relevant") notoriously does the most explanatory work but receives the least formal specification — what counts as "relevant" is left to intuition. Relevance Theory makes this precise. Moreover, Grice's maxims can conflict, requiring ad hoc adjudication; Relevance Theory has only one principle. More importantly, Relevance Theory handles a wider range of phenomena than classical implicature. It explains lexical pragmatics — why "Can you pass the salt?" is interpreted as a request and not a question about ability — and loose use — why "France is hexagonal" is true enough to assert despite France not being perfectly hexagonal. In both cases, the interpretation selected is the one that delivers the highest relevance: alternative interpretations either require more processing effort (the literal ability-question interpretation) or yield fewer cognitive effects (a pedantically precise interpretation of France's borders).
The key analytical move Relevance Theory provides is the relevance-guided interpretation procedure: starting from the most accessible interpretation and stopping when relevance is achieved. This makes pragmatic interpretation not a matter of deliberate maxim-checking but an automatic, cognitively efficient process. It also predicts under-determination: a single utterance can be optimal-relevance-interpreted differently in different contexts, because context changes what cognitive effects are available. Your knowledge of formal pragmatics gives you the background to see why this matters — Relevance Theory does not replace truth-conditional semantics but adds an inferential layer above it, explaining how the minimal linguistic meaning of an utterance becomes a full pragmatic interpretation in context. Where Gricean accounts require listeners to detect maxim violations and generate implicatures as repairs, Relevance Theory describes a smoother, unified process in which every step in interpretation is guided by the search for optimal relevance.