Full Idea
If there were impossible objects, ones that do not possibly exist, we would have no difficulty in understanding what it is for such objects to be identical or distinct than in the case of possible objects.
Gist of Idea
We would understand identity between objects, even if their existence was impossible
Source
Kit Fine (Necessity and Non-Existence [2005], 08)
Book Reference
Fine,Kit: 'Modality and Tense' [OUP 2005], p.344
A Reaction
Thus, a 'circular square' seems to be the same as a 'square circle'. Fine is arguing for identity to be independent of any questions of existence.