Full Idea
It is difficult for Resemblance Nominalists to construct their interconnected classes in practice.
Gist of Idea
'Resemblance Nominalism' finds that in practice the construction of resemblance classes is hard
Source
David M. Armstrong (Universals [1995], p.503)
Book Reference
'A Companion to Metaphysics', ed/tr. Kim,Jaegwon/Sosa,Ernest [Blackwell 1995], p.503
A Reaction
Given the complexity of the world this is hardly surprising, but it doesn't seem insuperable for the theory. It is hard to decide whether an object is white, or hot, whatever your theory of universals.