Prior, Arthur Norman (1914–1969)

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Arthur Norman Prior was born on December 4 at Masterton, near Wellington, New Zealand. He acknowledged an early philosophical debt to John Findlay. But his first academic post was at Canterbury University College, where he succeeded Karl Popper. He was the visiting John Locke Lecturer at Oxford in 1956, and in 1958 he was appointed a professor of philosophy at the University of Manchester. After short periods as a visiting professor at the University of Chicago and at the University of California at Los Angeles, he moved in 1966 to a tutorial fellowship at Balliol College, Oxford, and Oxford University appointed him to a concurrent readership.

Prior's early intellectual interests were very much religious in character. He was influenced for several years by the theologian Arthur Miller, who combined a strict adherence to Presbyterian doctrine with an equally strong support for socialism and opposition to nationalism. But Prior's pacifism weakened, and he served from 1942 to 1945 in the New Zealand air force. And the central focus of his interests gradually shiftedhelped by an occasional bout of atheismfrom theology to ethics and logic. He exchanged ideas with a wide circle of friends and acquaintances, and his hospitality to students was legendary.

Prior's first book, Logic and the Basis of Ethics (1949) traced seventeenth-, eighteenth-, and nineteenth-century anticipations of G. E. Moore's criticism of the so-called naturalistic fallacy. But his main claim to fame lies in his pioneering work on the formal logic of temporal relationships. His most important investigations in this field were published in Time and Modality (1957), Past, Present, and Future (1967), and Papers on Time and Tense (1968). But he also wrote on several logical topics in this encyclopedia; he published a substantial survey of the current state of logical inquiry under the title of Formal Logic (1955; 2nd ed., 1962); and a posthumous volume of papers, Objects of Thought (1971), was edited by P. T. Geach and A. J. P. Kenny.

Prior almost always used the Polish style of notation in the discussion of logical proofs and principles and was a convinced, though largely unsuccessful, champion of its virtues. The major inadequacy in his tense logic, however, was a failure to discuss or accommodate aspectual differencesroughly, differences between the meanings expressed by verbs in a perfect tense and those expressed by verbs in an imperfect tense (see Galton, 1984). Other criticisms may be found in L. J. Cohen's (1958) review of Time and Modality and in his subsequent controversy with Prior (Philosophy 34 [1959]). In his Formal Logic Prior displayed an impressively wide acquaintance with logical systems outside the field of tense logic, and this book remains a useful text for anyone interested in comparisons between different axiomatizations of the propositional calculus, between different kinds of logical quantification, between different modal logics, or between different three-valued or institutionist logics. But the treatment of metalogical issues in the book is occasionally rather selective: for example, in its discussion of completeness proofs for the predicate calculus as against its treatment of completeness proofs for the propositional calculus.

Outside the brilliant originality of his work on tense logic, perhaps Prior's most striking idea was expressed in "The Runabout Inference-Ticket" (1960), where he argued that, if the meaning of a logical connective consisted just in the logical uses to which it can be put (as many seemed to hold), then it would be easy to invent a connective with a meaning that would enable one to infer any conclusion from any premises.

See also Atheism; Modal Logic; Moore, George Edward; Nationalism; Pacifism; Popper, Karl Raimund; Socialism.


works by prior

Logic and the Basis of Ethics. Oxford: Clarendon Press, 1949.

Formal Logic. Oxford: Clarendon Press, 1955. 2nd ed., 1962.

Time and Modality. Oxford: Clarendon Press, 1957.

"The Runabout Inference-Ticket." Analysis 21 (1960): 3839.

Past, Present, and Future. Oxford: Clarendon Press, 1967.

Papers on Time and Tense. Oxford: Clarendon Press, 1968.

Objects of Thought, edited by P. T. Geach and A. J. P. Kenny. Oxford: Clarendon Press, 1971.

works on prior

Cohen, L. J. Review of Time and Modality. Philosophical Quarterly 8 (1958): 266271.

Gallon, A. The Logic of Aspect. Oxford: Clarendon Press, 1984.

L. J. Cohen (1996)