Dependence, Separability, and Theories of Identity and Distinction in Late Medieval Philosophy: Case Studies from Scotus and Ockham

Theories of distinctions surface some of the most fundamental elements of metaphysical and logical inquiry. For many medieval philosophers, theories of distinctions provided some semblance of rational order and unity to metaphysical, logical and theological questions. The two philosophers on which I focus, John Duns Scotus and William Ockham, discuss distinctions and metaphysical adjuncts in a variety of philosophical and theological contexts. When discussing Scotus, I emphasize his development of a robust theory of identity and distinction. I give special attention to his accounts of what he calls qualified non-identity or qualified distinction, which he surprisingly says is compatible with real identity. When I turn my attention to Ockham, I focus on his use of the real distinction in the context of the common fourteenth century disputes about universals.The question of separability has long been a central one for various theories of distinctions. Students of medieval philosophy who have interacted with Scotus's theory of distinctions have generally assumed two distinct claims: (1) that the real distinction entails separability; and (2) that the formal distinction entails inseparability. I raise concerns for both of those claims. The rejection of assumption (2) depends on a careful (and controversial) reading of Scotus's account. On the other hand, the rejection of (1) is comparatively straightforward, though perhaps still controversial.Ockham's interesting claims about universals make reference only to the real distinction (or its denial). Thus the emphasis in what follows is on Ockham's account of the real distinction and the proper conditions for separability when such a distinction obtains. Because Ockham's account of the distinctions is simpler than Scotus's in important ways, the discussion of separability might initially seem like it ought to be simpler as well. Surprisingly, Ockham's account of separability in relation to the real distinction - the only relevant case, since he denies the general usefulness of the formal distinction - is complicated, and he seems to deny that separability is possible in every case in which a real distinction obtains