William of Ockham was a controversial fourteenth-century Franciscan friar and scholar. His work focused at first on philosophy and logic and later on the separation of Church and state. He deeply influenced European ideas about the practice of science, well into the Scientific Revolution of the seventeenth century.
Studies as a Franciscan
William of Ockham was probably born about 1287 in Ockham, a village near London in Surrey. When he was still a boy of perhaps 8 years old, his family dedicated him to serve the Church in the Franciscan Order and sent him to the Franciscan convent in London. This was a piece of good fortune, since his career and education as a scholar were subsidized by the Order. This was one way in which someone from an undistinguished background could pursue a career in the Church.
The Franciscan School in London was called Greyfriars. It was an excellent school. Ockham learned Latin there, and from the age of 14, basic logic and natural science. He was ordained Subdeacon in 1306 at Southwark near London, and became licensed to hear confessions by 1318. In fact, we can infer his date of birth from these dates, which are known from official records.
Ockham attended Oxford University starting in 1309. He lectured on the Bible from 1314-1316, which was required of candidates for the Master of Theology degree. In 1317-1319 he fulfilled another required for his Theology degree by lecturing on the Sentences of Peter Lombard. 
After lecturing on the Sentences Ockham taught and participated in disputations. He even gave an inaugural lecture as a theologian, but he did not actually receive a degree and become a master, which is why he is called "The Venerable Inceptor."
Ockham never became a master because he did not fulfill the last requirement for the degree, which was to teach for a year at Oxford as a master. At the time there was only one such post open to Franciscans, so he had to wait his turn.
While waiting Ockham taught at Greyfriars in London, where he remained from 1321-23. There he led a lively intellectual life, receiving sharp critical input from Walter Chatton and Adam Wodeham. He produced his Quodlibetal Questions, parts of his Summa Logicae, and a revised version of the reportatio of the first book of his Lectures on the Sentences (the “Ordinatio” on Book I).
Controversy and Inquiry
Ockham was brilliant and intellectually uncompromising. In some circles, he began to gain a reputation for unorthodox views. While he was at Oxford, Walter Burley opposed his views and went on to write a response to Ockham’s logical works. Chatton, at Greyfriars, seemed determined to refute him at every turn.
In 1323, Ockham was asked to defend his views in a provincial chapter meeting at Bristol. By 1324, someone had complained to the Papal Court at Avignon about Ockham, and he was summoned there to defend himself. He was never to return to England or teach at Oxford, so he did not become a Master of Theology.
In 1326 the commission of theologians established to hear Ockham's case tentatively declared that 51 propositions in Ockham’s writings were worthy of censure, and that 29 of these were heretical, but that was as far as things went. No papal pronouncement against him was based on the work of the commission -- events intervened before there could be any final resolution of the matter.
Ockham's troubles with the Pope
One would have thought Ockham was in enough hot water, but he managed to get into yet more trouble. He stayed at the Franciscan convent in Avignon, but there is no record of any restrictions on his activities. Though he must have shown up for hearings, of course, Ockham continued with his scholarly work.
At Avignon, Ockham met Michael of Cesena, then Minister General of the Franciscan Order. Under Cesena's influence, Ockham became involved in the major controversy then affecting the Franciscan order: Did Christ and his apostles own anything? If not, then, in imitation of Christ and following their vows, neither should the Franciscans. Franciscan friars should depend for their living on the charity of the community. They could legitimately live by begging while following their preaching vocation wandering around outside the convent. Indeed, the convent building itself would not belong to the Order, nor would the friars even have any right to make use of it. Permission might be granted to them by the owner, but such permission could be withdrawn at any time.
This Franciscan position was legally and administratively impractical and had alienated many of the powerful people of the Church. The matter was eventually settled by compromise: The Order and its members could have a right to use things, though they did not own them. “Use” could thus be given a status under the law equivalent to ownership, satisfying the needs of administration, while the Friars could continue to live without owning anything in imitation of Christ.
Instead of accepting the compromise, however, Ockham sided with the position taken by the order in 1321 at Perugia and espoused by the so-called “Michaelists.” Ockham was encouraged in his defiance by Michael Cesena. Michael was, in fact, in Avignon to defend his friars from charges of heresy: Pope John XXII had rejected the doctrine of the poverty of Christ as heretical in 1323. So the "Michaelist" party faced increasing pressure to acquiesce, but they did not do so.
After a confrontation between Michael and the Pope, Ockham and a few principal members of the Order fled from Avignon in 1328. Ockham was particularly well-advised to flee, since he had argued openly that Pope John’s opposition to the Franciscan teaching about Christ's poverty was heretical. On this point Ockham agreed with the position stated by Louis of Bavaria, Holy Roman Emperor in 1324.
Ockham also defended Louis' claim that John's stubborn adherence to his views, even after others had attempted to correct him many times, made him no Pope at all! (Was Ockham right? Some experts on church law held that he would have been right if the doctrine of Christ’s absolute poverty was an established doctrine of the Church. Ockham thought that Pope Nicholas III had established the doctrine in 1279. According to the general opinion of the Catholic Church, however, Nicholas never defined this teaching as dogma.)
The refugees fled under cover of night to Pisa in Italy, where they found refuge with Louis of Bavaria. Louis was continually at odds with the Pope over the powers of the Church in secular affairs. In fact, before the Emperor had declared the Pope a heretic, the Pope had disputed Louis' election as Emperor. The election had been opposed by a minority of princes whom Louis defeated after eight years in 1322 at the Battle of Muhldorf. The Pope claimed the right to decide such disputed elections, inasmuch as it was his job officially to present the Emperor with the regalia of his office. There is a legend that when Ockham arrived before Emperor Louis, he said to him, “O Imperator, defende me gladio, et ego defendam te verbo.”
Eventually the little group of Franciscan refugees followed Louis to Munich. Excommunicated for leaving Avignon without permission, Ockham spent the rest of his life in Munich writing controversial works on Church-State relations, the limits of legitimate authority, and Papal power. He never returned to philosophical matters. Instead he wrote continuously in defense of Louis against John XXII, against Benedict XII, and against Clement VI (John's immediate successors).
In support of Ockham's work, in 1338 the German princes declared that whomever the majority of the Electors chose was King of the Holy Roman Empire, a central European territory. without any need of confirmation or investiture by the Pope. But in 1346 Louis’s cards seem played out, and the princes, weary of the excommunication and the endless struggle with the Pope, tried to end the affair by electing Charles of Luxembourg in Louis’ place. In 1347 Louis died, avoiding complete humiliation at the hands of his enemies.
Ockham was left without a protector, and all of his companions were dead or reconciled with the Church. People used to think that Ockham also tried to reconcile himself with his Order and the Church — that he had returned the Seal of the Order, obtained from Michael Cesena, and that the General Chapter of the Order interceded for him with the Pope. But, in fact, the seal seems to have been returned by a different “William of England.” Ockham died in 1347, apparently still recalcitrant.
God's Absolute Power and Theology
Ockham held strict views not only about Christ's poverty and about ontology, but also about what we can know. His strict views about knowledge and scientific demonstration led him to hold different theological views from many older theologians in several respects.
Ockham denied, for instance, that we can prove that there is only one God, since we cannot be certain that there is only one universe. Perhaps we could show “the most perfect of beings” exists. But we could not show that there was only such being, God. There might be several such beings, all equally perfect. Ockham did not deny that there was one God —he said that Christians "know" there is one God. Unlike older theologians, however, Ockham said we could not prove this by natural reason. We only know that there is one God, because sacred scripture says there is.
Similarly, some of Ockham’s opinions about God’s absolute power conflict with Roman Catholic notions about what God can do. In particular, Ockham held to a divine command theory of morality. He argued that God freely determined from eternity what was good and bad and made human reason able to know his determinations in these matters -- just as human reason knows that there are natural laws governing the physical world.
God’s will thus precedes God’s intellect. God does not, as Thomas Aquinas would have it, first determine the nature of the good and then seek it. Rather, what God seeks is necessarily the good simply because he wills it. This “Voluntarism,” as it is sometimes called, is rooted in Ockham’s conviction that God is not simply good and a being, but rather that God is the standard itself by which goodness and being are identified. So it is not possible that God should fail either to be, or to be good.
God's Absolute Power and Knowledge of the
Natural World: Ockham's Razor
Ockham's beliefs about God's absolute power also led him to restrict what we can know about the natural world. Considering only his power, God could connect any cause to any effect. That means that an examination of the underlying nature of a thing, considered in itself and absolutely, cannot reveal its causal properties. These can only be known through observation, coupled with the knowledge that there are natural regularities established by God that we can discover.
An observable regularity most likely reflects the operation of a natural cause. For example, observing that eclipses occur when the earth comes between the sun and moon shows us what causes eclipses. However, given the limits of what we can know, Ockham thought we should affirm only:
- what is self-evident or what can be deduced from self-evident propositions
- a proposition of Faith or what can be deduced from propositions of the Faith
- what sense experience indicates or what we know from experience.
Ockham added to these requirements what the foundations of human knowledge are. He held that our explanations must be economical. They should assume as little as possible and not postulate theoretical entities unnecessarily. This principle of parisimony, though not original with Ockham, has long been associated with him and is often called Ockham's razor.
Philosophical Thought: No Real Universals
Ockham’s philosophical thought is founded on a few underlying doctrines. Most importantly, he rejected the notion that Real Universals, or shared common natures, exist and explain particular things. Ockham insisted that the world is composed of particulars alone. These include accidents as well as substances.
The key to figuring out what really exists in the world is to note that two things are “really distinct” only if each can exist without the other. Logically speaking if we cannot think of one thing without another, then we are not really thinking of two things, but of one. One thing may appear to be two on account of the relations it has to other things, particularly relations to our intellect or senses, but this appearance is illusory.
Consider roses. There are two things that must happen if there is to be a real universal. Let us say this real universal is “the nature of a rose,” which is distinct from the individual roses that this nature is found in. First, the same identical nature (not merely similar natures) must be present in different roses. Somehow this nature must be the same as the nature found in one particular rose. But Ockham argues that this is impossible: Suppose for the sake of argument that the "nature of a rose" is really distinct from a particular rose. It still cannot be really distinct from itself, as it would have to be if really the same nature were really present in different roses. So if there is a universal, there can only be one nature, even though there are several roses. But the same thing cannot be many and one -- singular and universal -- at the same time. So the universal nature cannot be the same as the individual rose.
The second thing that must happen is that the real nature must be both in the rose and in the mind as a concept. Concepts in the mind and the things we conceive can exist apart from each other, when each is considered simply by itself. That is, even if all roses were destroyed, we could still have in mind the concept of a rose. Similarly, roses could exist, even if no one had a concept of a rose in mind. So the rose in the external world and its concept are two different things and have two different natures. The rose is a flower and the concept is a representation of the flower in someone’s mind. They have a real relation to one another -- the concept resembles the actual rose. Indeed it bears the greatest such similarity any concept can have to a rose. But this similarity is not due to anything that is identically the same in both the rose and our concept of a rose.
In fact, it is very difficult to understand what Ockham meant by claiming that things and their concepts are similar. But Ockham thought they had to be in order to account for the fact that the concept of a rose (and not some other concept) naturally arises from acquaintance with roses. Indeed, Ockham held that concepts signify their objects naturally, not by convention, within a universal mental language common to all human beings. There are universals, but they do not exist in the external world independently of language. Rather universals are concepts -- or mental words -- suited to stand for and to serve as a basis for understanding more than one thing. Universals are linguistic entities, different in kind from the objects they represent in the mind.
With this nominalistic conceptualism in place, Ockham attempted to lay out an ontology, an account of the sorts of things that are to be found as real beings in the world. Ockham appeals to God’s absolute power to determine whether two things are really distinct. If they are, then they can exist separately, at least if God sets aside the natural order of things; if not, then not even God can bring about that the one thing can exist without the other.
On this basis Ockham asks what kinds of things -- really distinct from one another -- could God have made, that would account for the world as we encounter it? Ockham argues that there are only two sorts of things that can be real, independently existing things: particular substances and particular qualities. In the natural order, qualities do not exist separately, but always belong to a particular substance in the natural order. By God's absolute power, however, they could exist independently and be associated with a determinate time and place.
By contrast, relations and quantities could not exist independently of substances and qualities even by God's absolute power. Rather, the terms we use to refer to relations are just shorthand expressions that describe complex states of affairs, necessarily involving substances and qualities. For example, we speak of 'paternity', but there is no such thing as paternity that we can point to in the external world. There are only men and their children, related as father and son or father and daughter.
Ockham's Impact on his Peers and his Successors
Ockham’s philosophy is deeply considered, and rooted in a thorough knowledge and appreciation of the work of his predecessors, especially John Duns Scotus. It also presents a philosophical vision of things strongly unified by carefully thought-out Empiricist principles. His influence was somewhat limited on account of his disappearance early on from the academic scene at Oxford and the notoriety he gained defending the lost cause of the "Michaelists" and Louis of Bavaria.
Nonetheless, such was the quality of the work Ockham had done before his flight from Avignon that it continued to be consulted at Oxford. Indeed, some fourteenth-century English thinkers saw Ockham's fundamental principles as the key to philosophical truth. By the fifteenth century, a school of "nominalist" or "terminist" thought had arisen, establishing itself at Oxford, in Italy, Germany, Austria, the Czech Republic, and France. Along with the Scotists, Averroists, and Thomists, this school was a major presence in the universities at the end of the Middle Ages.
Moreover, Ockham's influence extends beyond the Renaissance and the later Middle Ages. Ockham's empiricism and realism in the modern sense helped shape the climate in which early modern British philosophy and science developed. The "Venerable Inceptor" -- was a major thinker of the later Middle Ages, whose ideas gave a new direction to the metaphysics and theories of knowledge.