Full Idea
If the Identity of Indiscernibles is referring to qualitative properties, such as 'being red' or 'having mass', it is contentious; if it is referring to non-qualitative properties, such as 'member of set s' or 'brother of a', it is true but trivial.
Gist of Idea
The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities
Source
Joseph Melia (Modality [2003], Ch.3 n 11)
Book Reference
Melia,Joseph: 'Modality' [Acumen 2003], p.177
A Reaction
I would say 'false' rather than 'contentious'. No one has ever offered a way of distinguishing two electrons, but that doesn't mean there is just one (very busy) electron. The problem is that 'indiscernible' is only an epistemological concept.