1916 – 2013
Peter Geach (1916–2013) was a British analytic philosopher renowned for his work in philosophical logic, philosophy of language, and metaphysics, with a strong commitment to Thomistic and Aristotelian thought. He made foundational contributions to theories of predication, reference, and identity, while simultaneously engaging with medieval logic and scholastic metaphysics. His marriage to G.E.M. Anscombe placed him at the center of mid-twentieth-century analytic Catholic philosophy.
Developed the relative identity thesis, arguing that identity statements are only meaningful relative to a sortal predicate
Authored Reference and Generality (1962), a major work reconceiving predication and the logic of general terms
Formulated the Geach–Kaplan sentence, a landmark example demonstrating limits of first-order logic
Wrote Mental Acts (1957), influencing philosophy of mind by defending an abstractionist account of concept formation
Revived engagement with medieval Aristotelian-Thomistic logic within the analytic tradition