Any theory saying that if we are to refer to an object we must be in some relevant causal contact with it. We cannot therefore refer to fictitious objects, but must be using their names in some other way.
Suppose that I try talking about one 'Ebenezer Pilkington, who is "F"' (where 'F is some elaborate description, satisfied by one person only, who happens also to be the only person called 'Ebenezer Pilkington'); and suppose that all this is pure coincidence and I have never heard of him or been in any causal contact with him.
On the views in question I am not referring to him, whatever else I am doing.
These views are akin to the causal theory of names, though not the same since only people refer.
S Kripke, Naming and Necessity (1980)