The first certain date of Ockham’s life is that he was ordained subdeacon in 1306. He joined the Franciscans, and lectured on the Sentences of Peter Lombard in Oxford between 1317 and 1319. His progress towards master of theology was halted by one Peter Lutterell, an ‘overzealous Thomist’, who accused Ockham of heresy before the university and the Pope. In 1328 his relations with the papacy deteriorated further when he defended, on behalf of the Franciscans and against the papacy, the doctrine that Jesus and the disciples owned no property; Ockham was forced to take refuge with Emperor Louis of Bavaria. He may have died of the Black Death, in the course of moves of reconciliation with the papacy.

Ockham is famous as the leader of the nominalists, or those who denied the reality of universals, or real distinct properties and natures apart from the things possessing them. While Ockham certainly held that everything that exists outside the mind is singular, he also allowed the mind a power of abstractive cognition (e.g. Bk. ii of the Sentences, q. 15), so his position may be nearer to a form of conceptualism. With the abandonment of realism about universals goes the epistemology postulating cognitions of intelligible species, and Ockham’s own epistemology depends on the intuitive cognition of particular, single things, and subsequent abstraction. Ockham’s scrupulous attention to the nature of language and to logic, as well as his doctrine of abstraction, makes him a forerunner of subsequent British empiricism. Ockham’s chief works are the Four Books of the Sentences, written around 1323, the Summa of Logic (before 1329), and the Quodlibeta septem (before 1333).