William of Ockham OFM
William of Ockham depicted on a stained glass window at All Saints' Church, Ockham[5]
Born	1287 (1287) Ockham, Surrey, England
Died	9 April 1347(1347-04-09) (aged 59–60) Munich, Duchy of Bavaria, Holy Roman Empire
Education	Greyfriars, London[6]
Alma mater	University of Oxford[7][8]
Notable work	Summa Logicae
Era	14th-century philosophy Medieval philosophy
Region	Western philosophy
School	Scholasticism Occamism Nominalism[a] Theological voluntarism[1]
Main interests	Natural philosophy metaphysics epistemology theology logic ontology politics Theological voluntarism
Notable ideas	Occam's razor Nominalism Empiricism[2]

William of Ockham or Occam OFM (/ˈɒkəm/ OK-əm; Latin: Gulielmus Occamus;^[9][10] c. 1287 – 10 April 1347) was an English Franciscan friar, scholastic philosopher, apologist, and Catholic theologian, who is believed to have been born in Ockham, a small village in Surrey.^[11] He is considered to be one of the major figures of medieval thought and was at the centre of the major intellectual and political controversies of the 14th century. He is commonly known for Occam's razor, the methodological principle that bears his name, and also produced significant works on logic, physics and theology. William is remembered in the Church of England with a commemoration on the 10th of April.^[12]

William of Ockham was born in Ockham, Surrey, in 1287.^[13] He received his elementary education in the London House of the Greyfriars.^[14] It is believed that he then studied theology at the University of Oxford^[7][8] from 1309 to 1321,^[15] but while he completed all the requirements for a master's degree in theology, he was never made a regent master.^[16] Because of this he acquired the honorific title Venerabilis Inceptor, or "Venerable Beginner" (an inceptor was a student formally admitted to the ranks of teachers by the university authorities).^[17]

During the Middle Ages, theologian Peter Lombard's Sentences (1150) had become a standard work of theology, and many ambitious theological scholars wrote commentaries on it.^[18] William of Ockham was among these scholarly commentators. However, William's commentary was not well received by his colleagues, or by the Church authorities.^[19] In 1324, his commentary was condemned as unorthodox and he was ordered to Avignon, France, to defend himself before the papal court.^[18]

An alternative understanding, recently proposed by George Knysh, suggests that he was initially appointed in Avignon as a professor of philosophy in the Franciscan school, and that his disciplinary difficulties did not begin until 1327.^[20] It is generally believed that these charges were levied by Oxford chancellor John Lutterell.^[21][22] The Franciscan Minister General, Michael of Cesena, had been summoned to Avignon, to answer charges of heresy. A theological commission had been asked to review his Commentary on the Sentences, and it was during this that William of Ockham found himself involved in a different debate. Michael of Cesena had asked William to review arguments surrounding Apostolic poverty. The Franciscans believed that Jesus and his apostles owned no property either individually or in common, and the Rule of Saint Francis commanded members of the order to follow this practice.^[23] This brought them into conflict with Pope John XXII.

Because of the pope's attack on the Rule of Saint Francis, William of Ockham, Michael of Cesena and other leading Franciscans fled Avignon on 26 May 1328, and eventually took refuge in the court of the Holy Roman Emperor Louis IV of Bavaria, who was also engaged in dispute with the papacy, and became William's patron.^[18] After studying the works of John XXII and previous papal statements, William agreed with the Minister General. In return for protection and patronage William wrote treatises that argued for Emperor Louis to have supreme control over church and state in the Holy Roman Empire.^[18] "On June 6, 1328, William was officially excommunicated for leaving Avignon without permission",^[16] and William argued that John XXII was a heretic for attacking the doctrine of Apostolic poverty and the Rule of Saint Francis, which had been endorsed by previous popes.^[16] William of Ockham's philosophy was never officially condemned as heretical.^[16]

He spent much of the remainder of his life writing about political issues, including the relative authority and rights of the spiritual and temporal powers. After Michael of Cesena's death in 1342, William became the leader of the small band of Franciscan dissidents living in exile with Louis IV. William of Ockham died (prior to the outbreak of the plague) on 9 April 1347.^[24]

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In scholasticism, William of Ockham advocated reform in both method and content, the aim of which was simplification. William incorporated much of the work of some previous theologians, especially Duns Scotus. From Duns Scotus, William of Ockham derived his view of divine omnipotence, his view of grace and justification, much of his epistemology and ethical convictions.^[25] However, he also reacted to and against Scotus in the areas of predestination, penance, his understanding of universals, his formal distinction ex parte rei (that is, "as applied to created things"), and his view of parsimony which became known as Occam's razor.

William of Ockham espoused fideism, stating that "only faith gives us access to theological truths. The ways of God are not open to reason, for God has freely chosen to create a world and establish a way of salvation within it apart from any necessary laws that human logic or rationality can uncover."^[26] He believed that science was a matter of discovery and saw God as the only ontological necessity.^[16] His importance is as a theologian with a strongly developed interest in logical method, and whose approach was critical rather than system building.^[27]

William of Ockham was a pioneer of nominalism, and some consider him the father of modern epistemology, because of his strongly argued position that only individuals exist, rather than supra-individual universals, essences, or forms, and that universals are the products of abstraction from individuals by the human mind and have no extra-mental existence.^[28] He denied the real existence of metaphysical universals and advocated the reduction of ontology.^{[citation needed]}

William of Ockham is sometimes considered an advocate of conceptualism rather than nominalism, for whereas nominalists held that universals were merely names, i.e. words rather than extant realities, conceptualists held that they were mental concepts, i.e. the names were names of concepts, which do exist, although only in the mind. Therefore, the universal concept has for its object, not a reality existing in the world outside us, but an internal representation which is a product of the understanding itself and which "supposes" in the mind the things to which the mind attributes it; that is, it holds, for the time being, the place of the things which it represents. It is the term of the reflective act of the mind. Hence the universal is not a mere word, as Roscelin taught, nor a sermo, as Peter Abelard held, namely the word as used in the sentence, but the mental substitute for real things, and the term of the reflective process. For this reason William has sometimes also been called a "Terminist", to distinguish him from a nominalist or a conceptualist.^[29]

William of Ockham was a theological voluntarist who believed that if God had wanted to, he could have become incarnate as a donkey or an ox, or even as both a donkey and a man at the same time. He was criticized for this belief by his fellow theologians and philosophers.^[30]

One important contribution that he made to modern science and modern intellectual culture was efficient reasoning with the principle of parsimony in explanation and theory building that came to be known as Occam's razor. This maxim, as interpreted by Bertrand Russell,^[31] states that if one can explain a phenomenon without assuming this or that hypothetical entity, there is no ground for assuming it, i.e. that one should always opt for an explanation in terms of the fewest possible causes, factors, or variables. He turned this into a concern for ontological parsimony; the principle says that one should not multiply entities beyond necessity—Entia non sunt multiplicanda sine necessitate—although this well-known formulation of the principle is not to be found in any of William's extant writings.^[32] He formulates it as: "For nothing ought to be posited without a reason given, unless it is self-evident (literally, known through itself) or known by experience or proved by the authority of Sacred Scripture."^[33] For William of Ockham, the only truly necessary entity is God; everything else is contingent. He thus does not accept the principle of sufficient reason, rejects the distinction between essence and existence, and opposes the Thomistic doctrine of active and passive intellect. His scepticism to which his ontological parsimony request leads appears in his doctrine that human reason can prove neither the immortality of the soul; nor the existence, unity, and infinity of God. These truths, he teaches, are known to us by revelation alone.^[29]

William wrote a great deal on natural philosophy, including a long commentary on Aristotle's Physics.^[34] According to the principle of ontological parsimony, he holds that we do not need to allow entities in all ten of Aristotle's categories; we thus do not need the category of quantity, as the mathematical entities are not "real". Mathematics must be applied to other categories, such as the categories of substance or qualities, thus anticipating modern scientific renaissance while violating Aristotelian prohibition of metabasis.

In the theory of knowledge, William rejected the scholastic theory of species, as unnecessary and not supported by experience, in favour of a theory of abstraction. This was an important development in late medieval epistemology. He also distinguished between intuitive and abstract cognition; intuitive cognition depends on the existence or non-existence of the object, whereas abstractive cognition "abstracts" the object from the existence predicate. Interpreters are, as yet, undecided about the roles of these two types of cognitive activities.^[35]

William of Ockham is also increasingly being recognized as an important contributor to the development of Western constitutional ideas, especially those of government with limited responsibility.^[36] He was one of the first medieval authors to advocate a form of church/state separation,^[36] and was important for the early development of the notion of property rights. His political ideas are regarded as "natural" or "secular", holding for a secular absolutism.^[36] The views on monarchical accountability espoused in his Dialogus (written between 1332 and 1347)^[37] greatly influenced the Conciliar movement.^[38]

William argued for complete separation of spiritual rule and earthly rule.^[39] He thought that the pope and churchmen have no right or grounds at all for secular rule like having property, citing 2 Timothy 2:4. That belongs solely to earthly rulers, who may also accuse the pope of crimes, if need be.^[40]

After the Fall he believed God had given humanity, including non-Christians, two powers: private ownership and the right to set their rulers, who should serve the interest of the people, not some special interests. Thus he preceded Thomas Hobbes in formulating social contract theory along with earlier scholars.^[40]

William of Ockham said that the Franciscans avoided both private and common ownership by using commodities, including food and clothes, without any rights, with mere usus facti, the ownership still belonging to the donor of the item or to the pope. Their opponents such as Pope John XXII wrote that use without any ownership cannot be justified: "It is impossible that an external deed could be just if the person has no right to do it."^[40]

Thus the disputes on the heresy of Franciscans led William of Ockham and others to formulate some fundamentals of economic theory and the theory of ownership.^[40]

In logic, William of Ockham wrote down in words the formulae that would later be called De Morgan's laws,^[41] and he pondered ternary logic, that is, a logical system with three truth values; a concept that would be taken up again in the mathematical logic of the 19th and 20th centuries. His contributions to semantics, especially to the maturing theory of supposition, are still studied by logicians.^[42][43] William of Ockham was probably the first logician to treat empty terms in Aristotelian syllogistic effectively; he devised an empty term semantics that exactly fit the syllogistic. Specifically, an argument is valid according to William's semantics if and only if it is valid according to Prior Analytics.^[44]

William of Ockham denied papal infallibility and often went into conflict with the pope.^[45] As a result, some theologians have viewed him as a proto-Protestant.^[46] However, despite his conflicts with the papacy he did not renounce the Roman Catholic Church.^[47] Ockham also held that councils of the Church were fallible, he held that any individual could err on matters of faith, and councils being composed of multiple fallible individuals could err.^[48] He thus foreshadowed some elements of Luther's view of sola scriptura.^[49][50][51]

Ockham taught the separation of church and state, believing that the pope and emperor should be separate.^[47]

Ockham advocated for voluntary poverty.^[52]

Ockham opposed Pope John XXII on the question of the Beatific Vision. John had proposed that the souls of Christians did not instantly get to enjoy the vision of God, rather such vision would be postponed until the last judgement.^[53]

William of Ockham and his works have been discussed as a possible influence on several late medieval literary figures and works, especially Geoffrey Chaucer, but also Jean Molinet, the Gawain poet, François Rabelais, John Skelton, Julian of Norwich, the York and Townely Plays, and Renaissance romances. Only in very few of these cases is it possible to demonstrate direct links to William of Ockham or his texts. Correspondences between Ockhamist and Nominalist philosophy/theology and literary texts from medieval to postmodern times have been discussed within the scholarly paradigm of literary nominalism.^[54] Erasmus, in his Praise of Folly, criticized him together with Duns Scotus as fuelling unnecessary controversies inside the Church.

The standard edition of the philosophical and theological works is: William of Ockham: Opera philosophica et theologica, Gedeon Gál, et al., eds. 17 vols. St. Bonaventure, New York: The Franciscan Institute, 1967–1988.

The seventh volume of the Opera Philosophica contains the doubtful and spurious works.

The political works, all but the Dialogus, have been edited in H. S. Offler, et al., eds. Guilelmi de Ockham Opera Politica, 4 vols., 1940–1997, Manchester: Manchester University Press [vols. 1–3]; Oxford: Oxford University Press [vol. 4].

Abbreviations: OT = Opera Theologica vol. 1–10; OP = Opera Philosophica vol. 1–7.

• Summa logicae (Sum of Logic) (c. 1323, OP 1).
• Expositionis in Libros artis logicae prooemium, 1321–1324, OP 2).
• Expositio in librum Porphyrii de Praedicabilibus, 1321–1324, OP 2).
• Expositio in librum Praedicamentorum Aristotelis, 1321–1324, OP 2).
• Expositio in librum in librum Perihermenias Aristotelis, 1321–1324, OP 2).
• Tractatus de praedestinatione et de prescientia dei respectu futurorum contingentium (Treatise on Predestination and God's Foreknowledge with respect to Future Contingents, 1322–1324, OP 2).
• Expositio super libros Elenchorum (Exposition of Aristotle's Sophistic refutations, 1322–1324, OP 3).
• Expositio in libros Physicorum Aristotelis. Prologus et Libri I–III (Exposition of Aristotle's Physics) (1322–1324, OP 4).
• Expositio in libros Physicorum Aristotelis. Prologus et Libri IV–VIII (Exposition of Aristotle's Physics) (1322–1324, OP 5).
• Brevis summa libri Physicorum (Brief Summa of the Physics, 1322–23, OP 6).
• Summula philosophiae naturalis (Little Summa of Natural Philosophy, 1319–1321, OP 6).
• Quaestiones in libros Physicorum Aristotelis (Questions on Aristotle's Books of the Physics, before 1324, OP 6).

• In libros Sententiarum (Commentary on the Sentences of Peter Lombard).
  • Book I (Ordinatio) completed shortly after July 1318 (OT 1–4).
  • Books II–IV (Reportatio) 1317–18 (transcription of the lectures; OT 5–7).
• Quaestiones variae (OT 8).
• Quodlibeta septem (before 1327) (OT 9).
• Tractatus de quantitate (1323–24. OT 10).
• Tractatus de corpore Christi (1323–24, OT 10).

• Opus nonaginta dierum (1332–1334).
• Epistola ad fratres minores (1334).
• Dialogus (before 1335).
• Tractatus contra Johannem [XXII] (1335).
• Tractatus contra Benedictum [XII] (1337–38).
• Octo quaestiones de potestate papae (1340–41).
• Consultatio de causa matrimoniali (1341–42).
• Breviloquium (1341–42).
• De imperatorum et pontificum potestate [also known as Defensorium] (1346–47).

• Tractatus minor logicae (Lesser Treatise on logic) (1340–1347?, OP 7).
• Elementarium logicae (Primer of logic) (1340–1347?, OP 7).

• Tractatus de praedicamentis (OP 7).
• Quaestio de relatione (OP 7).
• Centiloquium (OP 7).
• Tractatus de principiis theologiae (OP 7).

• Philosophical Writings, tr. P. Boehner, rev. S. Brown (Indianapolis, Indiana, 1990)
• Ockham's Theory of Terms: Part I of the Summa logicae, translated by Michael J. Loux (Notre Dame; London: University of Notre Dame Press, 1974) [translation of Summa logicae, part 1]
• Ockham's Theory of Propositions: Part II of the Summa logicae, translated by Alfred J. Freddoso and Henry Schuurman (Notre Dame: University of Notre Dame Press, 1980) [translation of Summa logicae, part 2]
• Demonstration and Scientific Knowledge in William of Ockham: a Translation of Summa logicae III-II, De syllogismo demonstrativo, and Selections from the Prologue to the Ordinatio, translated by John Lee Longeway (Notre Dame, Indiana: University of Notre Dame, 2007)
• Ockham on Aristotle's Physics: A Translation of Ockham's Brevis Summa Libri Physicorum, translated by Julian Davies (St. Bonaventure, New York: The Franciscan Institute, 1989)
• Kluge, Eike-Henner W., "William of Ockham's Commentary on Porphyry: Introduction and English Translation", Franciscan Studies 33, pp. 171–254, JSTOR 41974891, and 34, pp. 306–382, JSTOR 44080318 (1973–74)
• Predestination, God's Foreknowledge, and Future Contingents, translated by Marilyn McCord Adams and Norman Kretzmann (New York: Appleton-Century-Crofts, 1969) [translation of Tractatus de praedestinatione et de praescientia Dei et de futuris contigentibus]
• Quodlibetal Questions, translated by Alfred J. Freddoso and Francis E. Kelley, 2 vols (New Haven; London: Yale University Press, 1991) (translation of Quodlibeta septem)
• Paul Spade, Five Texts on the Mediaeval Problem of Universals: Porphyry, Boethius, Abelard, Duns Scotus, Ockham (Indianapolis, Indiana: Hackett, 1994) [Five questions on Universals from His Ordinatio d. 2 qq. 4–8]

• The De sacramento altaris of William of Ockham, translated by T. Bruce Birch (Burlington, Iowa: Lutheran Literary Board, 1930) [translation of Treatise on Quantity and On the Body of Christ]

• An princeps pro suo uccursu, scilicet guerrae, possit recipere bona ecclesiarum, etiam invito papa, translated Cary J. Nederman, in Political thought in early fourteenth-century England: treatises by Walter of Milemete, William of Pagula, and William of Ockham (Tempe, Arizona: Arizona Center for Medieval and Renaissance Studies, 2002)
• A translation of William of Ockham's Work of Ninety Days, translated by John Kilcullen and John Scott (Lewiston, New York: E. Mellen Press, 2001) [translation of Opus nonaginta dierum]
• Tractatus de principiis theologiae, translated in A compendium of Ockham's teachings: a translation of the Tractatus de principiis theologiae, translated by Julian Davies (St. Bonaventure, New York: Franciscan Institute, St. Bonaventure University, 1998)
• On the Power of Emperors and Popes, translated by Annabel S. Brett (Bristol, 1998)
• Rega Wood, Ockham on the Virtues (West Lafayette, Indiana: Purdue University Press, 1997) [includes translation of On the Connection of the Virtues]
• A Letter to the Friars Minor, and Other Writings, translated by John Kilcullen (Cambridge: Cambridge University Press, 1995) [includes translation of Epistola ad Fratres Minores]
• A Short Discourse on the Tyrannical Government, translated by John Kilcullen (Cambridge: Cambridge University Press, 1992) [translation of Breviloquium de principatu tyrannico]
• William of Ockham, [Question One of] Eight Questions on the Power of the Pope, translated by Jonathan Robinson^[55]

William of Occam served as an inspiration for the creation of William of Baskerville, the main character of Umberto Eco's novel The Name of the Rose, and is the main character of La Abadía del Crimen (The Abbey of Crime), a video game based upon said novel.

• Occam's razor
• Gabriel Biel
• Philotheus Boehner
• History of science#Middle Ages
• List of Catholic clergy scientists
• List of scholastic philosophers
• Ernest Addison Moody
• occam (programming language)
• Ockham algebra
• Oxford Franciscan school
• Rule according to higher law
• Terminism

• Adams, Marilyn (1987). William Ockham. Notre Dame: University of Notre Dame Press. ISBN 0-268-01940-1.
• Beckmann, Jan (1992). Ockham-Bibliographie, 1900–1990. Hamburg: F. Meiner Verlag. ISBN 978-3-7873-1103-3.
• Freppert, Lucan (1988). The Basis of Morality According to William Ockham. Franciscan Herald Press. ISBN 978-0-8199-0918-3.
• Keele, Rondo (2010). Ockham Explained: From Razor to Rebellion. Chicago and La Salle, Illinois: Open Court. ISBN 978-08126-965-09. Retrieved 19 November 2012.
• Knysh, George (1996). Political Ockhamism. Winnipeg: WCU Council of Learned Societies. ISBN 978-1-896637-00-6.
• Labellarte, Alberto (2015). Logica, conoscenza e filosofia della natura in Guglielmo di Ockham. Roma: Gruppo Albatros Il Filo. ISBN 978-88-567-7421-4.
• Lenzen, Wolfgang (2015). "Ockham's Calculus of Strict Implication". Logica Universalis. 9 (2): 181–191. doi:10.1007/s11787-014-0114-4. S2CID 11132528.
• McGrade, Arthur Stephen (2002). The Political Thought of William Ockham. Cambridge University Press. ISBN 978-0-521-52224-3.
• Panaccio, Claude (2004). Ockham on Concepts. Aldershot: Ashgate. ISBN 978-0-7546-3228-3.
• Pelletier, Jenny (2012). William Ockham on Metaphysics. The Science of Being and God. Leiden: Brill. ISBN 978-9-0042-3015-6.
• Robinson, Jonathan (2012). William of Ockham's Early Theory of Property Rights in Context. Leiden: Brill. ISBN 978-9-0042-4346-0.
• Schierbaum, Sonja (2014). Ockham's Assumption of Mental Speech: Thinking in a World of Particulars. Leiden: Brill. ISBN 978-9-0042-7734-2.
• Spade, Paul (1999). The Cambridge Companion to Ockham. Cambridge: Cambridge University Press. ISBN 0-521-58244-X.
• Wood, Rega (1997). Ockham on the Virtues. Purdue University Press. ISBN 978-1-55753-097-4.

• Mediaeval Logic and Philosophy, maintained by Paul Vincent Spade
• "William of Ockham" entry by Paul Vincent Spade, Claude Panaccio, Jenny Pelletier in the Stanford Encyclopedia of Philosophy
• William of Ockham at the Internet Encyclopedia of Philosophy
• William of Ockham biography at University of St Andrews, Scotland
• Dialogus, text translation and studies at British Academy, UK
• The Nominalist Ontology of William of Ockham, with an annotated bibliography
• Richard Utz and Terry Barakat, "Medieval Nominalism and the Literary Questions: Selected Studies." Perspicuitas
• The Myth of Occam's Razor by William M. Thorburn (1918)
• BBC Radio 4 'In Our Time' programme on Ockham Download and listen
• Literature by and about William of Ockham in the German National Library catalogue
• Works by and about William of Ockham in the Deutsche Digitale Bibliothek (German Digital Library)
• "Occam, Guillelmus". Repertorium "Historical Sources of the German Middle Ages" (Geschichtsquellen des deutschen Mittelalters).