Full Idea
There are some who claim that there can be uninstantiated universals, which are not exemplified by any particular, past, present or future; this would certainly imply that those universals have a Platonic transcendent existence outside time and space.
Gist of Idea
It is claimed that some universals are not exemplified by any particular, so must exist separately
Source
David M. Armstrong (Universals [1995], p.504)
Book Reference
'A Companion to Metaphysics', ed/tr. Kim,Jaegwon/Sosa,Ernest [Blackwell 1995], p.504
A Reaction
Presumably this is potentially circular or defeasible, because one can deny the universal simply because there is no particular.