I’m pointing out that the negation of S=”X observes A at time T” does not imply that X exists. S’=”X observes ~A at time T” is subset of ~S, but not the whole thing (X not existing at all at time T is also a negation, for example). Therefore, merely because S’ is impossible, does not mean that S is certain.
The point about introducing differences in observers, is that this is the kind of thing that your theory has to track, checking when an observer is sufficiently divergent that they can be considered different/the same. Since I take a more “god’s eye view” of these problems (extinctions can happen, even without observers to observe them), it doesn’t matter to me whether various observers are “the same” or not.
I’m pointing out that the negation of S=”X observes A at time T” does not imply that X exists. S’=”X observes ~A at time T” is subset of ~S, but not the whole thing (X not existing at all at time T is also a negation, for example). Therefore, merely because S’ is impossible, does not mean that S is certain.
The point about introducing differences in observers, is that this is the kind of thing that your theory has to track, checking when an observer is sufficiently divergent that they can be considered different/the same. Since I take a more “god’s eye view” of these problems (extinctions can happen, even without observers to observe them), it doesn’t matter to me whether various observers are “the same” or not.