Full Idea
In the Identity of Indiscernibles, one speaks about properties, and the notion of a property is by no means clearly fixed and formalized in modern symbolic logic.
Gist of Idea
The notion of 'property' is unclear for a logical version of the Identity of Indiscernibles
Source
C. Anthony Anderson (Identity and Existence in Logic [2014], 1.5)
Book Reference
'Bloomsbury Companion to Philosophical Logic', ed/tr. Horsten,L/Pettigrew,R [Bloomsbury 2014], p.60
A Reaction
The unclarity of 'property' is a bee in my philosophical bonnet, in speech, and in metaphysics, as well as in logic. It may well be the central problem in our attempts to understand the world in general terms. He cites intensional logic as promising.