Ph.D., Princeton, 1960. Joined the faculty in 1960. His interests are in logic, the philosophy of mathematics, epistemology, metaphysics, and the philosophy of language. He has written on these subjects for journals and collections and is currently doing work in the philosophy of mathematics, specifically on the interconnections between theories of knowledge and theories of the meaning of mathematical statements. With Hilary Putnam, of Harvard, he is co-editor of Philosophy of Mathematics: Selected Readings.