Full Idea
If intentionality sometimes involves a relation to nonexistent objects, like my dreamed-of visit to a Greek island, then such thoughts cannot be explained physically or causally, because only actual physical entities and events can be mentioned.
Gist of Idea
Reduction of intentionality involving nonexistent objects is impossible, as reduction must be to what is actual
Source
Dale Jacquette (Ontology [2002], Ch.10)
Book Reference
Jacquette,Dale: 'Ontology' [Acumen 2002], p.244
A Reaction
Unimpressive. Thoughts of a Greek island will obviously reduce to memories of islands and Greece and travel brochures. Memory clearly retains past events in the present, and hence past events can be part of the material used in reductive accounts.