William of Ockham

William of Ockham was an English Franciscan friar, philosopher and theologian of the early fourteenth century. He is best known for nominalism, the view that only individual things exist and that general terms are signs rather than names of shared realities, and for the principle of economy in explanation later called Ockham's razor. In the second half of his life he broke with the pope, fled to the court of the emperor Ludwig of Bavaria and wrote powerful attacks on papal claims to power.

Little is known of his early years. He was probably born in late 1287 or early 1288 in the village of Ockham in Surrey, south-west of London, in the Kingdom of England. As a boy he was given to the Franciscans, the order of friars founded by Francis of Assisi, and was educated at their house in London, known as Greyfriars.

By about 1317 he was studying theology at Oxford, where he gave the required lectures on the Sentences of Peter Lombard, the standard textbook of the day. He completed the requirements for a master's degree but never formally took up the post, which is why he came to be called the "Venerable Inceptor", a beginner. Around 1321 he returned to London Greyfriars, a lively centre of debate where he lived alongside sharp critics of his own ideas, such as Walter Chatton and Adam Wodeham. Most of his philosophical works, including the Summa Logicae (Sum of Logic), date from these years.

His opinions aroused suspicion. In 1323 he had to defend them before a meeting of the English Franciscans, and someone denounced him for heresy at the papal court in Avignon. In 1324 he was summoned there, and a commission of theologians examined a list of his propositions. The inquiry dragged on for years and censured some of his views, but none was ever formally condemned as heretical.

In Avignon he became caught up in a much larger conflict. Pope John XXII had rejected the Franciscan teaching that Christ and the apostles owned nothing at all, individually or in common, a doctrine central to the order's identity. The head of the order, Michael of Cesena, asked Ockham to study the pope's statements. Ockham concluded that John was not just mistaken but a heretic, and so no true pope. On the night of 26 May 1328, Michael, Ockham and a few companions fled Avignon. They were excommunicated soon after.

The fugitives found protection with Ludwig IV of Bavaria, who was himself in conflict with John XXII over the pope's refusal to recognise him as emperor of the Holy Roman Empire. By about 1330 they had settled in Munich, where Ockham spent the rest of his life. A famous story has him telling the emperor that if Ludwig defended him with the sword, he would defend Ludwig with the pen; it is almost certainly a later invention, but it captures the arrangement.

In exile he wrote only on politics and church government, in works such as the Dialogus and the Eight Questions on the Power of the Pope. He argued that the pope's authority was limited, that it did not extend over temporal rulers, who received their power independently of the papacy, and that a pope who fell into heresy could be judged and deposed by the church. Even a general council could err; truth might be preserved by only a few believers. He died in Munich, probably on 9 or 10 April 1347. An older tradition placing his death in 1349, during the Black Death, is now generally rejected.

Ockham's central philosophical idea concerns universals, the general natures that terms such as "human" seem to name. Most of his predecessors, including Thomas Aquinas and Duns Scotus, held in different ways that such natures were in some sense real in individual things. Ockham argued that everything that exists is individual. A universal is only a concept in the mind, or a word, that signifies many individuals at once because they resemble one another. Peter Abelard had reached a similar position two centuries earlier, but Ockham worked it out in far more detail through a theory of how terms signify and stand for things in sentences.

He also reduced the categories of real things. Where many followers of Aristotle counted ten kinds of entity, Ockham accepted only individual substances, such as particular dogs and stones, and their individual qualities; relations, quantities and the rest were ways of talking about these. Behind this lay the principle that one should not multiply entities without necessity, or more exactly, that nothing should be assumed without reason, experience or the authority of scripture. Ockham did not invent the idea and never used the phrase that later became famous, but he applied it so consistently that it took his name.

Ockham stressed God's absolute power: God can do anything that does not involve a contradiction, and the order of the world depends on his free choice rather than on necessity. This led him to doubt that reason alone could prove many truths of theology, such as that there is only one God, which he held on faith. He argued that knowledge begins with "intuitive cognition", a direct awareness of particular things that tells us whether they exist. In ethics he emphasised the will, both God's and human, and held that the moral law depends on God's command, although he also gave right reason a large role.

Ockham's followers and critics formed the "modern way" (via moderna) that competed with the older schools of Aquinas and Scotus in the universities of the later Middle Ages. Through teachers such as Gabriel Biel, nominalist theology formed part of the education of Martin Luther. Historians once blamed Ockham for breaking up the medieval synthesis of faith and reason; most now see him as a careful logician and a major figure of Medieval Christian Philosophy. His political writings were read by later critics of papal power, and his razor remains a working rule in science and philosophy. He is one of the most important philosophers in the history of the United Kingdom and its predecessor states.