Occam, or Occham (William of), was a celebrated scholastic divine in the 14th century, of the order of Cordeliers. He was a native of England, and disciple to the famous Duns Scotus. He was head of the Nominalists; and acquired so much celebrity, as to be denominated the Invincible Doctor.

At the request of Michael de Cefena, general of his order, he became a party-man with Lewis of Ravierie, who was an avowed enemy of the church of Rome; and he really wrote vigorously against pope John XXII. and his successors. Trithemius informs us, that he used to say to Lewis, "My Lord, let your sword defend me, and my pen shall be always ready to support you." He treated Charles and Clement in a book he wrote against them with gross scurrility.

This, however, was a bold, dangerous, and imprudent step, and cannot well be defended on any proper principle. The effect of it, as might be expected, was an accusation against him and Cefena. They were charged with maintaining, that neither Christ nor his apostles had any possessions at all, either in common or as private property. This doctrine gave rise to that pleasant question called the bread of the Cordeliers; and consisted in determining, whether the dominion of things consumed in the use, such as bread and wine, belonged to them, or only the simple use of them, without the dominion? Their rule not permitting them to have anything as property, Pope Nicolas III. who had been of their order, devised a method to enrich them, without breaking their rule. To this end he made an ordinance, that they should have only the usufruct of the estates which should be given to them, and that the foil and fund of all such donations should belong to the Roman church at large. By this means he gave them the possession of an almost infinite number of estates, in the name of the church of Rome: but on this account, Pope Nicolas's bull was revoked by John XXII. who condemned the use without the dominion, by his Extravaganta ad Conditorem. He also condemned, by another Extravaganta cum inter, the doctrine about the possession of estates by Christ and his apostles. Ockham and Cefena were also excommunicated, because they had departed from Avignon without the pope's licence, and had written against him. Ockham, however, was absolved, as is said, from this censure before he died, which was about the year 1347.

We have several pieces of his, which are written with considerable wit and subtlety. The reformed church sometimes makes use of his reasoning against the church of Rome. Melchior Goldalt printed, in his treatise upon monarchy, 413 questions of Ockham. His works are mentioned by many authors.