Full Idea
The full Identity of Indiscernibles excludes the existence in this world of a symmetrical object, which is reduced to half of itself by the principle. If symmetrical about all planes that bisect it, it is precluded altogether from existence.
Gist of Idea
By the principle of Indiscernibility, a symmetrical object could only be half of itself!
Source
David Wiggins (Sameness and Substance [1980], 2.2)
Book Reference
Wiggins,David: 'Sameness and Substance' [Blackwell 1980], p.57
A Reaction
A really nice objection. Do the parts even need to be symmetrical? My eyeballs can't be identical to one another, presumably. Electrons already gave the principle big trouble.