Frederic Brenton Fitch

Frederic Brenton Fitch (1908 – September 18, 1987) was an American logician, a Sterling Professor at Yale University.

Fitch earned his Ph.D. from Yale in 1934 under the supervision of F. S. C. Northrop.

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" (originally by Alonzo Church), which later became famous in context of the Knowability Paradox.

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