Full Idea
Trope theory needs extra ontological baggage, the Axioms of Resemblance. There is a principle of symmetry, and there is the failure of transitivity - except in the special case of exact resemblance.
Gist of Idea
Trope theory needs extra commitments, to symmetry and non-transitivity, unless resemblance is exact
Source
David M. Armstrong (Properties [1992], §2)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.171
A Reaction
[see text for fuller detail] Is it appropriate to describe such axioms as 'ontological' baggage? Interesting, though I suspect that any account of properties and predicates will have a similar baggage of commitments.