What if (3) Harry the Barber shaves all and only those who do not shave themselves? What follows from that?

It is impossible for Harry the Barber to shave all and only those who do not shave themselves. As we have seen, if Harry shaves all of those who do not shave themselves, then he must shave himself; and if he shaves only those who do not shave themselves, then he cannot shave himself. If Harry shaves all and only those who do not shave themselves, then he both shaves himself and does not shave himself, which is a contradiction and thus logically impossible.

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