Full Idea
Later standard theories said that a real distinction obtains between two things that can each exist without the other. For Scotus a real distinction requires only that one of the pair be able to exist without the other.
Gist of Idea
Are things distinct if they are both separate, or if only one of them can be separate?
Source
report of John Duns Scotus (In Metaphysics [1304], V.5-6 n91) by Robert Pasnau - Metaphysical Themes 1274-1671 12.5
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.241
A Reaction
His example is the similarity relation, which is independent of the whiteness on which it is based (since the other thing can become non-white).