Full Idea
Non-actual states of affairs are possible if there actually was a substance capable of initiating a causal chain, perhaps non-deterministic, that could lead to the state of affairs that we claim is possible.
Gist of Idea
A state of affairs is only possible if there has been an actual substance to initiate it
Source
Alexander R. Pruss (The Actual and the Possible [2002]), quoted by Jonathan D. Jacobs - A Powers Theory of Modality §4.2
Book Reference
-: 'Philosophical Studies' [-], p.12
A Reaction
This is roughly my view. There are far fewer possibilities in heaven and earth than are dreamt of in your philosophy, Horatio. Logical possibilities and fantasy possibilities are not real possibilities.