Alasdair Urquhart

Alasdair Ian Fenton Urquhart ( ; born 20 December 1945) is a Scottish–Canadian philosopher and emeritus professor of philosophy at the University of Toronto. He has made contributions to the field of logic, especially non-classical logic. Amongst his most notable accomplishments is the proof of undecidability of the relevance logic R. He published numerous scientific papers in theoretical computer science venues, mostly on mathematical logic topics of relevance to computer science.

Early life Urquhart is a native of Scotland. He received his MA in philosophy from the University of Edinburgh in 1967.

He is currently on the Council of the Division for Logic, Methodology and Philosophy of Science and Technology of the International Union of History and Philosophy of Science and Technology (2020–2023).

Selected publications Urquhart, Alasdair and Rescher, Nicholas. Temporal Logic. New York: Springer Verlag, 1971. Urquhart, Alasdair. "The Undecidability of Entailment and Relevant Implication." Journal of Symbolic Logic 49:4 (1984): 1059–1073. Urquhart, Alasdair and Cook, Stephen A. "Functional Interpretations of Feasibly Constructive Arithmetic", Annals of Pure and Applied Logic, 1993; preliminary version at STOC'89 "The Complexity of Decision Procedures in Relevance Logic II", Journal of Symbolic Logic 64:4 (1999): 1774–1802.