(The joke here is that, given the other axioms of ZF set theory, each of these three things can be used to prove the other two—they’re either all true or all false, regardless of how plausible or implausible they might seem on their own.)
(The joke here is that, given the other axioms of ZF set theory, each of these three things can be used to prove the other two—they’re either all true or all false, regardless of how plausible or implausible they might seem on their own.)