Richard Routley

Richard Routley (later Sylvan, 1935–1996) was a New Zealand-Australian philosopher and logician whose work transformed non-classical logic from a technical curiosity into a systematic philosophical program. He is best known as the co-founder of relevance logic (with Robert K. Meyer), a family of logics that reject the principle that a contradiction implies everything — the ex contradictione quodlibet that classical logic and intuitionistic logic both accept. Routley's philosophical motivation was not merely technical: he believed that classical logic systematically misrepresents the structure of valid inference by permitting irrelevant premises to determine conclusions.

Relevance Logic and the Meaning of Implication

Routley's central philosophical claim was that the classical material conditional — if