Here are some of his notable works:
* Summa Logicae (Summa of Logic): A comprehensive work on logic, considered one of the most important treatises on the subject in the medieval period.
* Quodlibetal Questions (Disputed Questions): A collection of philosophical and theological debates on various topics, including free will, the nature of God, and the relationship between faith and reason.
* Opus Nonaginta Dierum (Work of Ninety Days): A treatise on the power of the pope, challenging the papacy's authority over secular matters.
* Sentences Commentary: A commentary on Peter Lombard's Sentences, a standard textbook of theology in the Middle Ages.
William of Ockham is best known for his principle of Occam's Razor, which states that the simplest explanation is usually the best. However, he did not originate this principle, which was already in use by other philosophers.
While he did not specifically write a work called "Occam's Razor", his writings and debates about the nature of reality and the role of reason led to the popularization of this principle.