Full Idea
Many properties (being even) and relations (musical intervals, being a father) are such that it is not clear what it would mean to take them as natural things existing in space.
Gist of Idea
How could 'being even', or 'being a father', or a musical interval, exist naturally in space?
Source
J.P. Moreland (Universals [2001], Ch.4)
Book Reference
Moreland,J.P.: 'Universals' [Acumen 2001], p.89
A Reaction
'Being even' certainly seems to be a property, and it is a struggle to see how it could exist in space, unless it is a set of actual or potential brain states.