1901 – 1983
Alfred Tarski was a Polish-American logician and mathematician, widely regarded as one of the greatest logicians of the twentieth century. He made foundational contributions to model theory, formal semantics, and the theory of truth, most notably his semantic definition of truth for formalized languages. His work bridged mathematical logic, metamathematics, and the philosophy of language.
Formulated the semantic conception of truth (Convention T) in 'The Concept of Truth in Formalized Languages'
Founded modern model theory and developed the theory of cylindric algebras
Proved the undefinability of truth (Tarski's undefinability theorem)
Developed a decision procedure for elementary algebra and geometry (quantifier elimination for real closed fields)
Made major contributions to set theory, including work on large cardinals and the Banach-Tarski paradox
The second 'broad assumption' (¬p ∧ ¬Fp) → P¬Fp is not true when p refers to a future contingency
claimMetric geometry is neither true nor false.
claimThe apparent multiplication of word-tokens from a single inscription based on different readings is not a genuine mereological multiplication of entities