Born circa 1285 in Ockham, Surrey; died 1349 in Munich. English philosopher, logician, and religious and political writer. Representative of late Scholasticism.

A Franciscan monk, Ockham studied and taught at Oxford. In 1323 he was summoned to Avignon by Pope John XXII to respond to charges of heresy. He remained there for four years. He actively supported the head of the Franciscan Order, Michael of Cesena, in his dispute with the pope. From 1328, Ockham lived in Munich at the court of the pope’s adversary, Emperor Louis of Bavaria. According to legend, he told the emperor: “Defend me by the sword, and I will defend you by the pen.” In his political tracts, Ockham opposed the pope’s claims to secular power and the absolutism of ecclesiastical and secular authorities. He defended the principle of “evangelical poverty.” Many of his ideas anticipated the Reformation.

Ockham was the chief representative of nominalism in the 14th century. He asserted that only individual substances and their absolute qualities have real existence, and he proposed that, outside of thought, the universals are only names and terms signifying classes of names—terms of primary and secondary intention. “Real” sciences (those dealing with real objects) correspond to the terms of primary intention, and “rational” sciences (logic and grammar, for example) to the terms of secondary intention.

Ockham was one of the greatest logicians of the Middle Ages. In particular, he originated the idea that the meaning of a term is determined entirely by its function in an expression. In his theory of consequence he virtually distinguished between material and formal implication. He formulated the principle of the duality of conjunction and disjunction, and he asserted that primary cognition is intuitive and includes both external perception and introspection. Ockham insisted that concepts that cannot be reduced to intuitive knowledge and that cannot be verified experientially should be eliminated from science: “entities are not to be multiplied without necessity.” This principle, which came to be known as “Ockham’s razor,” played an important role in the struggle against medieval realism and the theory of “hidden qualities.” Believing that there can be no necessary link between individual substances, Ockham restricted the use of the concept of causation to empirical statements. He urged that philosophy and theology be divided into separate branches of study. Religious dogmas were defined by him as suprarational prescriptions relating not to reason but to faith and will. Like John Duns Scotus, he assigned will priority over reason. Ockham exerted a considerable influence on the subsequent development of logic and philosophy, especially on J. Buridan, Nicolaus of Autrecourt, and Hobbes.