"Proof" and "zero-knowledge" certainly still have meaning in the situation you've described. If we actually needed to do zk proofs over concepts like that, we'd

"Proof" and "zero-knowledge" certainly still have meaning in the situation you've described. If we actually needed to do zk proofs over concepts like that, we'd need defined ontologies and all sorts of logic to codify "the real world". My point is mostly that it can be a subjective thing between the prover and the verifier. The verifier simply needs to be convinced, without making it easier for a cheating provers or future cheating provers, and the prover needs to not help a cheating verifier.