 One sign of depth (or at least desperation) is that commentators begin rejecting highly credible inference rules. The surprise test has been claimed to invalidate the law of bivalence, the KK principle (if one is in a position to know that \(p\), then one is also in a position to know that one knows that \(p\)), and the closure principle (if one knows \(p\) while also competently deducing q from \(p\), one knows \(q\)) (Immerman 2017).