William (“Bill”) Walker Tait, professor emeritus of philosophy at the University of Chicago, has died.

Professor Tait was well-known for his work in philosophy of mathematics and logic, particularly proof theory. He is the author of The Provenance of Pure Reason: Essays in the Philosophy of Mathematics and its History, among many other works.

In a remembrance, Richard Zach (Calgary) discusses Professor Tait’s research:

He proved the consistency of second order logic, settling the Takeuti conjecture positively… His two most well-known contributions are perhaps the development of the Schütte-Tait method of proving cut elimination and the method of proving normalization for lambda calculus using Tait computability predicates… His most influential contribution in the philosophy of mathematics is what’s come to be known as “Tait’s thesis”: the identification of Hilbert’s “finitary standpoint” with what’s primitive recursively computable and provable in primitive recursive arithmetic.

You can learn more about his work here and here.

Professor Tait joined the philosophy faculty at Chicago in 1972. Prior to that, he held positions at the University of Illinois at Chicago and Stanford University. He earned his PhD from Yale University and his BA from Lehigh University.

You can read his own discussion of his life and work here.

Professor Tait died on March 15th, 2024.