Full Idea
Realism about universals is supported by the phenomenon of abstract reference - that is the fact that properties themselves have properties ('red is a colour'), and stand in relation to other properties ('red is more like orange than like blue').
Gist of Idea
Maybe universals are real, if properties themselves have properties, and relate to other properties
Source
J.P. Moreland (Universals [2001], Ch.1)
Book Reference
Moreland,J.P.: 'Universals' [Acumen 2001], p.6
A Reaction
While a property may be an obviously natural feature, properties of properties seem more likely to be the produce of human perception and convention. It is a good argument, though.