Full Idea
We are tempted to ask of second-order quantifiers 'what are you quantifying over?', or 'when you say "for some F" then what is the F?', but these questions already presuppose that the quantifiers are first-order.
Gist of Idea
If you ask what F the second-order quantifier quantifies over, you treat it as first-order
Source
Kit Fine (Replies on 'Limits of Abstraction' [2005])
Book Reference
-: 'Philosophical Studies' [-], p.379