Full Idea
The Fregean argument for platonism is that some true assertions contain singular terms which denote abstract objects if they denote anything; since the assertions are true, the singular terms denote.
Gist of Idea
Platonism claims that some true assertions have singular terms denoting abstractions, so abstractions exist
Source
Timothy Williamson (Review of Bob Hale's 'Abstract Objects' [1988])
Book Reference
-: 'Mind' [-], p.487
A Reaction
I am perplexed that anyone would rest their view of reality on such an argument. The obvious comparison would be with true remarks about blatantly fictional characters, or blatantly invented concepts such as 'checkmate'.