OCCAM, WILLIAM OF (c. 1300-1349), English school man, known as Doctor invincibilis and Venerabilis inceptor, was born at Ockham, Surrey, and after joining the Franciscans, studied from 1312 to 1318 at Merton college, Oxford, where he taught until 1324, when he was summoned to Avignon to account for some of his doctrines. While he was confined to his convent, in 1326, John XXII. ordered various theses from his works to be examined by the masters of theology, but his works were not actually condemned. Two years later his championship of the Spirituals brought him into a further conflict with the pope, and as a result, he and Michael of Cesena, general of the order, joined the emperor Louis of Bavaria who was at that time in contest with the papal curia. It was for Occam's share in this contro versy that he was best known in his lifetime. Michael of Cesena died in 1342, and Occam, who had received from him the official seal of the order, was recognized as general by his party. He probably died at Munich in 1349, having tried to be reconciled with the Church after the death of the emperor.
Occam was one of the most interesting figures in the great contest between pope and emperor, which laid the foundation of modern theories of government, in the disintegration of scholasti cism and in the rise of theological scepticism. In the Opus nona ginta dierum (1330) (written in reply to John XXII.'s libellus against Michael of Cesena), and in its successors, the Tractatus de dogmatibus Johannis XXII. papae (1333-34), the Compendium errorum Jehannis XXII. papae (1335-38) and in the Defensorium contra errores Johannis XXII. papae (1335-39), Occam only incidentally expounds his views as a publicist, the Compendium being of special interest because it selects f our papal constitu tions which involved a declaration against evangelical poverty, and insists that they are full of heresy. The Super potestate summi pontificis octo quaestionwn decisions (1339-42) attacks the temporal supremacy of the pope, insists on the independence of kingly authority, which he maintains is as much an ordinance of God as is spiritual rule, and discusses what is meant by the State. His views on the independence of civil rule were even more decidedly expressed in the Tractatus de jurisdictiaile impera toris in causis matrimonialibus, in which he contends that it belongs to the civil power to decide cases of affinity and to state the prohibited degrees. By 1343 his great work the Dialogus (see Goldast ii. 398-957), in which he attempted to summarize his views, was in circulation. His last work, De Electione Caroli IV., restates his opinions upon temporal authority.
In philosophy, Occam's most significant doctrines fall within the departments of psychology, metaphysics and theology. In the
first, he contends that since singulars alone exist, the universal, which is a kind of mental label, has an objective value only inasmuch as it is thought ; that the intellectus agens and the species intelligibiles are superfluous because abstraction follows naturally upon perceptions or intuition, the fundamental form of human knowledge ; that will and not intellect is the primary faculty of the soul, and that both faculties, like memory, are identical with the substance of the soul; and that a forma cor poreitatis must be admitted if the independence of the soul is to be preserved. In metaphysics, Occam teaches that matter has its own essence apart from form ; that accidents are only aspects of substance; that the problem of individuation is meaningless because each thing is singular in itself, and that between essence and existence there is no real distinction. The famous dictum Essentia non suet multiplicanda praeter necessitatem—has become known as "Occam's Razor," but it was already stressed by Duns Scotus. In theology, Occam's scepticism is especially noticeable in his assertion that the existence of God and His attributes, including His unity and infinity, are not strictly provable. Accord ing to Occam, the most characteristic activity of God is willing, and moral laws are good only because God wills them and not in their own right.
BIBLIOGRAFllY.-OCcaM'S political works were edited by Goldast (Frankfurt, 1614) and further mss. by R. Scholz (Rome, 1914). The Dialogus appeared separately in 1495, the Defensorium contra Joannem XXII. in 1513, and the De Imperatorum et pontificum potestate in 1927 (edit. C. K. Brampton). Of the non-political works, the Com mentary on the Sentences appeared in 1483 and 1495, the Quodlibet in 1487 and 1491 and the logical treatises fairly frequently in the 55th and 16th centuries.
See Prantl, Geschichte der Logik (1855-7o) ; Riezler, Die literarischen Widersacher der Piipste zur Zeit Ludwig des Baiers (1874) ; A. J. Little, Grey Friars in Oxford (1892) ; F. BruckmUller, Die gotteslehre W. v. Ockham (Munich, 1911) ; L. Kugler, Der Begriff d. Erkenntniss bei W. v. Ockham (Breslau, 1913) ; J. Hofer, "Biographische Studien fiber W. von Ockham" in Arch. Fran. Hist. (1913) ; R. L. Poole, Illustrations in Mediaeval Thought (2nd ed., 192o) ; A. Pelzer, "Les 51 articles de G. d'Occam censures a Avignon en 1326" in R. Hist. eccles. (5922) F. Federhofer, "Ein Beitrag zur Bibliographie and Biographic des W. v. Ockham" in Philos. Jahrb. (1925), and "Die Psych . . . W. v. Ockham," in Philos. Jahrb. (1926). Full bibliography in ITherweg, Gesch. der Philosophie (ed. 2, 1928) .