William of Ockham

William of Ockham was an English Franciscan friar, philosopher and theologian, and the most influential thinker of the fourteenth century. A brilliant logician, he championed nominalism — the view that only individual things exist, and that universals (“humanity”, “whiteness”) are merely concepts or signs that stand for many individuals — and he cut away the elaborate metaphysical entities of earlier scholastics (Scholasticism) with a principle of economy later named Ockham’s razor: “plurality should not be posited without necessity”. He emphasised God’s absolute freedom and the contingency of the created world, and insisted that knowledge begins with direct “intuitive cognition” of individual things. Summoned to Avignon on suspicion of heresy, he fled to the court of the Emperor and spent his last two decades writing against the political claims of the papacy. His “modern way” (via moderna) dominated late medieval universities and opened a path toward modern empiricism and science.

Life

William was born around 1287 in the village of Ockham, in Surrey, south-west of London. He joined the Franciscan order young and studied theology at Oxford, where, around 1317–19, he lectured on the Sentences of Peter Lombard, the standard theology textbook. He completed the requirements for the doctorate but never became a regent master, perhaps because his teachings were controversial — hence his nickname Venerabilis Inceptor (“venerable beginner”). The chancellor of Oxford, John Lutterell, accused him of heresy, and in 1324 he was summoned to the papal court at Avignon, where a commission examined fifty-one propositions from his writings; none was formally condemned.

In Avignon he became involved in the dispute between Pope John XXII and the Franciscans over apostolic poverty — whether Christ and the apostles owned nothing, as the Franciscans held. When the pope declared this view heretical, Ockham concluded that the pope himself was a heretic. In May 1328 he fled Avignon with the Franciscan minister-general Michael of Cesena, and was excommunicated. They took refuge with the Holy Roman Emperor Louis IV of Bavaria, then at war with the pope; Ockham is said to have told him, “Defend me with the sword, and I will defend you with the pen.” He spent the rest of his life in the Franciscan house in Munich, writing political works against papal absolutism. He died there around 1347, possibly of the Black Death.

Ockham’s razor

Ockham repeatedly invoked a principle of parsimony: “Plurality is never to be posited without necessity” (pluralitas non est ponenda sine necessitate) and “it is futile to do with more what can be done with fewer”. The famous formulation “entities are not to be multiplied beyond necessity” was coined later, by John Punch in 1639, and the principle was used before Ockham by others, including Aristotle and Duns Scotus. But Ockham used it so sharply against the metaphysical apparatus of his predecessors that it took his name. Its rationale was not that nature is simple — God could make the world as complex as He liked — but that we should affirm the existence of something only if experience, reason or revelation requires it.

Nominalism

The medieval problem of universals, inherited from Boethius, asked whether genera and species — “animal”, “man” — exist in reality. Realists held that a common nature, humanity, really exists in individual men; moderate realists, like Aquinas and Duns Scotus, that it exists in individuals though not separately. Ockham argued that every thing that exists outside the mind is individual (singular). A universal is not a thing but a sign — a concept in the mind, or a word — that “signifies” or “stands for” (supponit pro) many individuals. “Man” is common not because there is a common thing, humanity, in Socrates and Plato, but because it is a natural sign that applies to each.

Ockham developed this view through a sophisticated logic of terms — the theory of signification and supposition (the different ways a term stands for things in a proposition) — set out in his Summa Logicae, one of the masterpieces of medieval logic. He reduced Aristotle’s ten categories to two kinds of real things, substances and qualities; quantity, relation, place and time are not additional entities but ways of speaking about substances and qualities. A relation of similarity between two white things, for example, is not a third thing but just the two things being white.

Knowledge

Ockham distinguished intuitive cognition, the direct awareness of an individual thing as existing and present, by which we know contingent truths (that this wall is white), from abstractive cognition, which abstracts from existence. All knowledge of the world begins with intuitive cognition of individuals. He held, controversially, that God could by His absolute power produce in us an intuitive cognition of a non-existent object — which later thinkers saw as opening the door to scepticism, though Ockham held that such a cognition would cause us to judge correctly that the object did not exist.

He was sceptical about many proofs in natural theology: reason cannot demonstrate that there is only one God, or that the soul is immortal; these are known by faith. On causation, he held that we know that one thing causes another only by experience — by observing that when the one is present, the other follows — a view that anticipates Hume.

God’s absolute power

Ockham distinguished God’s absolute power (potentia absoluta) — His power to do anything that does not involve a contradiction — from His ordained power (potentia ordinata), by which He acts according to the order He has freely established. The created world, including the moral law, is radically contingent: God could have made it otherwise. In ethics this led him toward a divine-command view: God’s will is the ultimate standard of good and evil, and God could even command a creature to hate Him — though in fact He has established an order in which love of God is required.

Politics

From Munich, Ockham wrote voluminous works — the Work of Ninety Days, the Dialogus, the Breviloquium — against the claims of popes to “plenitude of power” over temporal rulers. The pope, he argued, has no power to command anything not required by divine law; temporal rulers derive their authority from the people, not the pope; and a pope who teaches heresy can be judged by a general council. He defended the natural right of property and the Franciscan ideal of poverty — the use of things without ownership — and became an early theorist of individual rights.

Legacy

Ockham’s followers — the nominales or moderni — dominated the universities of Paris, Oxford and Germany in the fourteenth and fifteenth centuries; the young Martin Luther was trained in the Ockhamist tradition. Later historians saw him as the destroyer of the medieval synthesis of faith and reason, or as a precursor of empiricism, modern science (through his followers Buridan and Oresme) and liberal political thought. Today his razor is a working principle of scientific method, and his logic is admired by analytic philosophers.

In conversation

• Ockham’s razor — no more entities than necessary.
• Universals as signs — nominalism against realism.
• “Defend me with the sword” — the philosopher and the emperor.