>No, you can't just assume you have supernatural powers, not even "in theory". If that is allowed, you could just say you are omniscient and thus know exactly what anyone will do, and thus there can be no free will. You have to play by the rules of the world we live in.
That sounds like 'logical determinism'. Statements about the future are true or false, therefore the future is something specific, set in stone. I agree with the conclusion, but there's something intuitively irksome about the reasoning...