Full Idea
Physical objects are identical if and only if coextensive.
Gist of Idea
Identity of physical objects is just being coextensive
Source
Willard Quine (On the Individuation of Attributes [1975], p.101)
Book Reference
Quine,Willard: 'Theories and Things' [Harvard 1981], p.101
A Reaction
The supposed counterexample to this is the statue and the clay it is made of, which are said to have different modal properties (destroying the statue doesn't destroy the clay).