Full Idea
There is a difficulty for any view of facts which sees them as being wholly abstract entities, and yet also being causal relata; for it seems that only concrete entities, existing in time and space, can enter into causal relations.
Gist of Idea
Facts cannot be wholly abstract if they enter into causal relations
Source
E.J. Lowe (The Possibility of Metaphysics [1998], 11.3)
Book Reference
Lowe,E.J.: 'The Possibility of Metaphysics' [OUP 2001], p.234
A Reaction
There seems a lot of ambiguity in the air here, between epistemology and ontology (surprise!). I take causation to be a physical activity in the concrete world. Our understanding of it is expressed with abstractions. 'Fact' seems to have two meanings.