  William of Ockham goes well beyond Scotus in his rejection of any kind of isomorphism between words, concepts, and things. Ockham is well known for what is usually called “nominalism,” that is, the view that universals or natures do not have any ontological status outside the mind. Moreover, in contrast to many fourteenth-century authors who posit ten categories, Ockham argues that our experience leads us to posit only two extra-mental categories: substance and quality.