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Jul 6, 2019 at 2:28 vote accept Pace Nielsen
Jun 24, 2019 at 15:04 comment added Timothy Chow By the way, in case you missed it, this MO question might interest you: mathoverflow.net/questions/331441/…
Jun 21, 2019 at 17:17 comment added Timothy Chow @PaceNielsen : I would suggest Torkel Franzén's book Inexhaustibility: A Non-Exhaustive Treatment, especially Chapter 7, which gives a detailed explanation of arithmetical truth.
Jun 21, 2019 at 15:54 comment added Pace Nielsen @TimothyChow Thank you for this answer. Would you have a good reference where I can learn more about (and the explicit definition of) arithmetical soundness and/or soundness in general?
Jun 21, 2019 at 12:55 comment added cody "No meta-theorem of this sort is known" Or, indeed, possible, since Con(ZFC) is a $\Pi^0_1$ statement already!
Jun 21, 2019 at 2:46 history edited Timothy Chow CC BY-SA 4.0
added 165 characters in body
Jun 21, 2019 at 2:44 comment added Timothy Chow Whoops! I mean that ZFC + universes could prove ¬Con(ZFC+universes).
Jun 21, 2019 at 2:43 comment added Noah Schweber "For example, it is conceivable that under these hypotheses, ZFC + universes could prove ¬Con(ZFC)." That's definitely false: ZFC + universes proves Con(ZFC), so if ZFC + universes is consistent it can't prove $\neg$Con(ZFC).
Jun 21, 2019 at 2:40 history answered Timothy Chow CC BY-SA 4.0