His two Wesleyan grandfathers, the Reverends Samuel Fowler Prior and Hugh Henwood Teague, were sent from England to South Australia as missionaries in 1875.

As the son of a doctor, Prior at first considered becoming a biologist, but ended up focusing on theology and philosophy, graduating from the University of Otago in 1935 with a B.A.

While studying for his B.A., Prior attended the seminary at Dunedin's Knox Theological Hall but decided against entering the Presbyterian ministry.

[7] In 1936, Prior married Clare Hunter, a freelance journalist, and they spent several years in Europe, during which they tried to earn a living as writers.

The correspondence is known as the Wartime letters, span more than several thousand pages and contain much important information about the development of Prior's view on several philosophical and theological matters.

[11] He began teaching philosophy and logic at Canterbury University College in February 1946, filling the vacancy created by Karl Popper's resignation.

Prior was several times warned by J. J. C. Smart against making tense-logic the topic of his John Locke lectures.

Smart feared that tense-logic would get Prior "involved in side issues, even straight philosophy, and not in the stuff that will do Oxford most good.

[14] During his time at Oxford, Prior met Peter Geach and William Kneale, influenced John Lemmon, and corresponded with the adolescent Saul Kripke.

Logic in the United Kingdom was then in a rather low state, being "deeply out of fashion and its practitioners were isolated and somewhat demoralized.

"[15] Prior arranged Logical a Colloquium which brought together such Logicians as John Lemmon, Peter Geach, Czesław Lejewski and more.

[16] The colloquiums were a great success and, together with Prior's John Locke lecture and his visits around the country, he helped revitalize British logic.