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|    Message 262,689 of 262,912    |
|    olcott to Mikko    |
|    Re: The Halting Problem asks for too muc    |
|    23 Jan 26 04:22:51    |
      XPost: sci.math, comp.theory       From: polcott333@gmail.com              On 1/23/2026 3:13 AM, Mikko wrote:       > On 22/01/2026 18:40, olcott wrote:       >> On 1/22/2026 2:21 AM, Mikko wrote:       >>> On 21/01/2026 17:22, olcott wrote:       >>>> On 1/21/2026 3:03 AM, Mikko wrote:       >>>>>       >>>>> No, it hasn't. In the way theories are usually discussed nothing is       >>>>> "ture in arithmetic". Every sentence of a first order theory that       >>>>> can be proven in the theory is true in every model theory. Every       >>>>> sentence of a theory that cannot be proven in the theory is false       >>>>> in some model of the theory.       >>>>>       >>>>>> only because back then proof theoretic semantics did       >>>>>> not exist.       >>>>>       >>>>> Every interpretation of the theory is a definition of semantics.       >>>>>       >>>>       >>>> Meta‑math relations about numbers don’t exist in PA       >>>> because PA only contains arithmetical relations—addition,       >>>> multiplication, ordering, primitive‑recursive predicates       >>>> about numbers themselves—while relations that talk about       >>>> PA’s own proofs, syntax, or truth conditions live entirely       >>>> in the meta‑theory;       >>>       >>> Methamathematics does not need any other relations between numbers       >>> than what PA has. But relations that map other things to numbers       >>> can be useful for methamathematical purposes.       >>>       >>>> so when someone appeals to a Gödel‑style relation like       >>>> “n encodes a proof of this very sentence,” they’re       >>>> invoking a meta‑mathematical predicate that PA cannot       >>>> internalize, which is exactly why your framework draws       >>>> a clean boundary between internal proof‑theoretic truth       >>>> and external model‑theoretic truth.       >>>       >>> Anyway, what can be provven that way is true aboout PA. You can deny       >>> the proof but you cannot perform what is meta-provably impossible.       >>       >> Gödel’s sentence is not “true in arithmetic.”       >> It is true only in the meta‑theory, under an       >> external interpretation of PA (typically the       >> standard model ℕ). Inside PA itself, the sentence       >> is not a truth‑bearer at all.       >       > There is no concept of "truth-bearer" in an uninterpreted theory because       > there is not concept of "truth". The relevant concept is "sell-formed-       > formula" and Gödels sentence is one. It may be true or false in an       > interpretation.       >              There is a       "true on the basis of meaning expressed in language"       and I figured out how to make it computable over the       body of knowledge.              > Gädel's metatheory contains PA. In Gödel's interpretation PA is       > interpreted in the same way as the PA part of the metathoéory.       > Gödel proves that G of PA as interpreted in the metatheory is       > true but cannot be proven in PA.       >                     --       Copyright 2026 Olcott |
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