William Ockham (c.1287–1347) was an English Franciscan friar, famous for his nominalism (Klima 2006), whose name is preserved in the commonly used designation of the methodological principle called ‘Ockham's razor’ (Adams 1987: 156–7, 281). This chapter will focus primarily on Ockham's nominalist doctrine and its impact on his theology.

William Ockham was born around 1287 in a little village called Ockham, twenty-five miles from London. He received his elementary education in London in the convent of the Franciscan order (the Greyfriars). At the time, the London House of the Greyfriars was a distinguished intellectual centre for not only elementary but also higher education, although it was not a university. Thus, having completed his studies in grammar, logic and natural philosophy, Ockham began studying theology there around the age of twenty-three, but soon moved on to Oxford. Probably in 1317, he began lecturing on the Sentences of Peter Lombard in Oxford, which was a general requirement for getting one's licence as a Master of Theology. However, in 1321, Ockham returned to the Franciscans in London before completing the programme at Oxford; thus he never became a Master of Theology (hence his honorific title, Inceptor Venerabilis, the venerable inceptor; that is, one who began work on, but has not received, his degree). Accordingly, it is only book I of his Commentary on the Sentences that exists in the form of an ordinatio (a text revised by the author himself for copying); the remaining three books exist only in the form of reportationes (unrevised lecture notes).