Full Idea
We should abandon the idea that the use of plural forms commits us to the existence of sets/classes… Entities are not to be multiplied beyond necessity. There are not two sorts of things in the world, individuals and collections.
Gist of Idea
The use of plurals doesn't commit us to sets; there do not exist individuals and collections
Source
George Boolos (To be is to be the value of a variable.. [1984]), quoted by Henry Laycock - Object
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.
A Reaction
The problem of quantifying over sets is notoriously difficult. Try http://plato.stanford.edu/entries/object/index.html.