Indistinguishability
A central bound in the theory concerns observational indistinguishability.
Consider two admissible possible worlds that differ in a fact relevant to the claim. For example:
text
World 1: no unauthorized consequential action occurred
World 2: an unauthorized consequential action occurred
If the claim is true in one world and false in the other, but both worlds produce identical observations under the specified observation model, that observation model cannot resolve the claim.
The important issue is that the worlds may differ in events, state, provenance, authorization, actions, or any other claim-relevant fact represented by the model.
The formal bound is therefore:
text
admissible worlds
+ identical observation
+ disagreement on claim truth
→ claim not resolved by that observation model