[citation needed] Belnap worked as a programmer on the IBM 701 for the National Security Agency through the United States Air Force for two years before attending graduate school at Yale University.
[1] He enjoyed metaphysics, and his professors included Paul Weiss, Arthur Pap, Henry Margenau, Frederic Fitch, and Rulon Wells.
Feys directed Belnap to read Wilhelm Ackermann's article on rigorous implication in the Journal of Symbolic Logic.
Belnap began to teach philosophy of social sciences, with students including Bas van Fraassen and Jon Michael Dunn.
[3] Wary of consequences of contradictory stored data, Belnap proposed a four-valued logic to avoid run-away inferences such as (A & ~A) → B for an arbitrary statement B.
Beyond propositional logic, they noted that the evolving databases make possible "dossier files on individuals" (page 146) leading to the "problem of privacy in record keeping."
The book included a 45-page annotated bibliography of erotetics, sectioned by philosophy, linguistics, automatic question-answering, and pedagogy, compiled by Hubert Schleichert and Urs Egli.
In 1982 at Stanford's Center for Advanced Studies in the Behavioral Sciences, and in 1996 at Leipzig, Centrum für Höhere Studien with Heirich Wansing.