6 ms·
The consistency of ZFC is (presumably) a theorem of second order PA, and ZFC is unable to prove it (unless ZFC is inconsistent).
by cevi 1y ago
The consistency of ZFC is (presumably) a theorem of second order PA, and ZFC is unable to prove it (unless ZFC is inconsistent).
- czbot 1y agoIndeed yes. But in a sense within ZFC one can say what N is given the categorical nature of second order PA. Each model of ZFC will have, up to isomorphism, one model of N.