Full Idea
If classes alone cannot be eliminated from ontology on Quine's terms, and if classes are defined as property combinations, then neither are all properties, universals in the tradition sense, entirely eliminable.
Gist of Idea
If classes can't be eliminated, and they are property combinations, then properties (universals) can't be either
Source
Dale Jacquette (Ontology [2002], Ch. 9)
Book Reference
Jacquette,Dale: 'Ontology' [Acumen 2002], p.230
A Reaction
If classes were totally conventional (and there was no such things as a 'natural' class) then you might admit something to a class without knowing its properties (as 'the thing in the box').