Full Idea
Boolos proposes that second-order quantifiers be regarded as 'plural quantifiers' are in ordinary language, and has developed a semantics along those lines. In this way they introduce no new ontology.
Gist of Idea
Second-order quantifiers are just like plural quantifiers in ordinary language, with no extra ontology
Source
report of George Boolos (To be is to be the value of a variable.. [1984]) by Stewart Shapiro - Foundations without Foundationalism 7 n32
Book Reference
Shapiro,Stewart: 'Foundations without Foundationalism' [OUP 1991], p.201
A Reaction
This presumably has to treat simple predicates and relations as simply groups of objects, rather than having platonic existence, or something.