William of Ockham 1287 – 1347

William of Ockham was an English Franciscan friar, philosopher, and theologian, one of the most important figures of late medieval thought. He defended a thoroughgoing nominalism, denying the real existence of universals outside the mind, and he is remembered for the methodological principle of parsimony now known as Ockham's razor. His political writings, composed during a long exile from the papal court at Avignon, articulated an early defense of limited papal power and natural rights. His logical and metaphysical works prepared the way for early modern philosophy and the new natural science.

William of Ockham was born around 1287 in the village of Ockham in Surrey. He entered the Franciscan order as a youth, studied theology at Oxford from about 1310, and lectured on the Sentences of Peter Lombard in the early 1320s. He never proceeded to the doctorate — earning him the medieval epithet inceptor — and in 1324 was summoned to the papal court at Avignon to answer charges of heterodoxy raised by the chancellor of Oxford.

While at Avignon he was drawn into the dispute between the Franciscan Spirituals and Pope John XXII over apostolic poverty. In 1328 he fled with the minister general Michael of Cesena to the court of the emperor Louis IV in Munich, where he was excommunicated and from which he wrote a long series of political works — the Dialogus, the Eight Questions, the Short Discourse — challenging papal absolutism. The earlier philosophical writings include the Summa Logicae, the Quodlibetal Questions, and his Sentences commentary.

Ockham's nominalism, his methodological razor against multiplied entities, his defense of divine omnipotence and human contingency, and his arguments for the limits of papal authority made him one of the most influential thinkers of the late Middle Ages and a founding figure of the via moderna. He died in Munich in 1347, probably of the Black Death.