  Even though Scotus does not believe that it can be demonstrated that there are only ten categories, he accepts that there are in fact only ten categories of being (Pini 2005). Clearly, for him, reality (the actual number of categories) and what we know about them (what we can demonstrate about them) do not correspond to each other. The categories, as distinct kinds of things, are diverse from each other and this diversity entails that there is nothing from which we can establish their number. As Pini notes, “[e]ven when Scotus comes to think that being is a univocal concept, he will always make clear that there is no one real mode of being corresponding to that concept from which the different categories can be derived. Metaphysically speaking, there are ten irreducible essences, even though they can be understood under a common concept” (Pini 2003, 13). Scotus' view of categories reveals that he does not accept the isomorphism between thought and reality common among medieval authors before him. For him, however, the inability to deduce the number of categories is only one of the ways in which signifying, understanding, and being are not demonstrably isomorphic.