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 corresponding to the commonly ascribed date of his death on 10 April.

[19] 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.

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.

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.

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.

[19] 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.

[17] 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.

[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.

[17] His importance is as a theologian with a strongly developed interest in logical method, and whose approach was critical rather than system building.

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.

[29] William wrote a great deal on natural philosophy, including a long commentary on Aristotle's Physics.

[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.

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.

[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.