Full Idea
An instantiation condition seems to be a failure of nerve as regards realism about universals. If universals really are entities in their own right, why should their existence depend upon a relationship with existing particulars?
Gist of Idea
Why should a universal's existence depend on instantiation in an existing particular?
Source
Alexander Bird (Nature's Metaphysics [2007], 3.2.2)
Book Reference
Bird,Alexander: 'Nature's Metaphysics' [OUP 2007], p.55
A Reaction
I like this challenge, which seems to leave fans of universals no option but full-blown Platonism, which most of them recognise as being deeply implausible.