Full Idea
Some thinkers claim the physical world consists just of relational properties - generally of active powers or fields; ..but an ontology of mutual influences is not an ontology at all unless the possessors of the influence have more substantial features.
Clarification
'Ontology' concerns what actually exists
Gist of Idea
If reality just has relational properties, what are its substantial ontological features?
Source
Howard Robinson (Perception [1994], IX.3)
Book Reference
Robinson,Howard: 'Perception' [Routledge 2001], p.220
A Reaction
I think this idea is one of the keys to wisdom. It is the same problem with functional explanations - you are left asking WHY this thing can have this particular function. Without the buck stopping at essences you are chasing your explanatory tail.