Frederic Fitch


Frederic Brenton Fitch was an American logician, a Sterling Professor at Yale University.

Education and career

At Yale, Fitch earned his B.A in 1931 and his Ph.D. from Yale in 1934 under the supervision of F. S. C. Northrop. From 1934 to 1937 Fitch was a postdoc at the University of Virginia. In 1937 he returned to Yale, where he taught until his retirement in 1977.
His doctoral students include Alan Ross Anderson, Ruth Barcan Marcus, and William W. Tait.

Work

Fitch was the inventor of the Fitch-style calculus for arranging formal logical proofs as diagrams. In his 1963 published paper "A Logical Analysis of Some Value Concepts" he proves "Theorem 5", which later became famous in context of the knowability paradox.
He also contributed to the philosophy of how logic relates to language.