Hm, how about: “[...] of any observer which our best current theory of how minds work says could exist”.
So for example, a statement along the lines of “a ghost watches and sees whether or not Mars continues to exist when it passes behind the Sun from Earth’s perspective” would have been meaningful a long time ago, but is not meaningful for people today who know a little about brains.
This also means that a proposition may be meaningful only because the proposer is ignorant.
Hm, how about: “[...] of any observer which our best current theory of how minds work says could exist”.
So for example, a statement along the lines of “a ghost watches and sees whether or not Mars continues to exist when it passes behind the Sun from Earth’s perspective” would have been meaningful a long time ago, but is not meaningful for people today who know a little about brains.
This also means that a proposition may be meaningful only because the proposer is ignorant.
Taboo “could”. Basically, counter-factual surgery is a lot trickier than you seem to think.