Re: Within Proof Theoretic Semantics Gödel's G h as no meaning in PA
dbush <[email protected]>
| Newsgroups | sci.logic,sci.math,comp.theory,comp.ai.philosophy,alt.philosophy |
|---|---|
| Organization | A noiseless patient Spider |
| Message-ID | <[email protected]> |
On 7/4/2026 1:07 PM, olcott wrote: > On 7/4/2026 3:06 AM, Mikko wrote: >> On 03/07/2026 21:20, olcott wrote: >>> On 7/3/2026 12:35 PM, André G. Isaak wrote: >>>> On 2026-07-03 09:38, olcott wrote: >>>>> On 7/3/2026 4:28 AM, Mikko wrote: >>>>>> On 02/07/2026 17:49, olcott wrote: >>>>>>> On 7/2/2026 1:55 AM, Mikko wrote: >>>>>>>> On 01/07/2026 18:16, olcott wrote: >>>>>>>>> On 7/1/2026 2:24 AM, Mikko wrote: >>>>>>>>>> On 30/06/2026 16:58, olcott wrote: >>>>>>>>>>> On 6/30/2026 3:18 AM, Mikko wrote: >>>>>>>>>>>> On 29/06/2026 16:29, olcott wrote: >>>>>>>>>>>>> On 6/29/2026 1:14 AM, Mikko wrote: >>>>>>>>>>>>>> On 29/06/2026 05:52, olcott wrote: >>>>>>>>>>>>>>> On 6/28/2026 3:39 AM, Mikko wrote: >>>>>>>>>>>>>>>> On 27/06/2026 17:50, polcott wrote: >>>>>>>>>>>>>>>>> On 6/27/2026 1:53 AM, Tristan Wibberley wrote: >>>>>>>>>>>>>>>>>> On 20/06/2026 18:32, olcott wrote: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> A proof theoretic expression is known to be true when >>>>>>>>>>>>>>>>>>> it is fully grounded in its atomic base. Only two >>>>>>>>>>>>>>>>>>> PTS semantics researchers deal with true Dag Prawitz >>>>>>>>>>>>>>>>>>> is the one that began this. PTS previously only dealt >>>>>>>>>>>>>>>>>>> with semantic meaning and never got around to true(L,x). >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> That's surprising, disregard for axioms? >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> If there is no sequence of inference steps in Q from >>>>>>>>>>>>>>>>> ~∃x x=S(x) to the axioms of Q then ~∃x x=S(x) is >>>>>>>>>>>>>>>>> ungrounded in the PTS atomic base of Q. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> This does not mean undecidable or incomplete >>>>>>>>>>>>>>>>> it means that ~∃x x=S(x) is out-of-scope for Q. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> It comes close. If ∃x x=S(x) is likewise "ungrounded" >>>>>>>>>>>>>>>> but in the >>>>>>>>>>>>>>>> language of Q then ~∃x x=S(x) and ∃x x=S(x) are both >>>>>>>>>>>>>>>> undecidable >>>>>>>>>>>>>>>> and Q is incomplete, bcause that is what the words mean. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Q also can't bake a birthday cake, this does not make >>>>>>>>>>>>>>> Q in any way "incomplete" relative to what it was >>>>>>>>>>>>>>> defined to do. Incomplete only counts relative to >>>>>>>>>>>>>>> its intended purpose. A car without an engine is >>>>>>>>>>>>>>> incomplete relative to a mode of transportation. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Irrelevant. The definition of completeness >>>>>>>>>>>>> >>>>>>>>>>>>> It a misnomer and does not literally mean (as it implies) >>>>>>>>>>>>> that something is missing that could be added to make >>>>>>>>>>>>> it complete. >>>>>>>>>>>> >>>>>>>>>>>> It does mean that something is missing that could be added to >>>>>>>>>>>> enabe a proof of an unprovable sentence. >>>>>>>>>>> >>>>>>>>>>> Base-Extension Semantics (B-eS) allows that. >>>>>>>>>>> It never was incomplete. It always did what it was defined to >>>>>>>>>>> do. >>>>>>>>>>> When Q is extended to become PA it stops being Q and becomes PA. >>>>>>>>>> >>>>>>>>>> However, there are theories that reamain incomplete even when >>>>>>>>>> more postolates are added, as long as there is a way to know >>>>>>>>>> which sentences are included in the added postulates. Important >>>>>>>>>> examples include Peano arithmetic and ZFC set theory. >>>>>>>>> >>>>>>>>> Base-Extension Semantics (B-eS) seems to be essentially a cheat. >>>>>>>>> When we ask what is grounded in an atomic base of Q and we >>>>>>>>> add axioms to Q to become PA we cheated in that we changed >>>>>>>>> the original question rather than answered it. >>>>>>>> >>>>>>>> Yes, in a sense. But sometimes it is better to have a partial >>>>>>>> answer >>>>>>>> rather than no answer at all. Of course Q with any additional >>>>>>>> postulate is not Q but if the additional postulates are true about >>>>>>>> natural numbers then the strengthened theory is still a theory of >>>>>>>> natural numbers. PA is one such strengthened Q but still incomplete >>>>>>>> and can be strengthened further. >>>>>>> >>>>>>> Is (∀x, S(x) ≠ x) provable or refutable in Q? >>>>>>> Yes if you cheat, no if you don't cheat. >>>>>> >>>>>> As I already pointed out in another message, which you apparently >>>>>> missed, it is neither. >>>>> >>>>> Thus PTS would say that (∀x, S(x) ≠ x) is semantically >>>>> undefined in Q. >>>> >>>> And that differs from claiming that Q is incomplete exactly how...? >>> >>> The base definition of "incomplete" means that it is >>> not operating according to design spec. >> >> No, it is not. The term "incomplete" in its base meaning is >> appicable to various things that are not exprected to operate. >> > > The English word "incomplete" establishes the base > meaning (parent node) in the knowledge ontology. > > I will not tolerate deceptive terms-of-the-art. In other words, you intend to lie by misusing definitions. > > A motor vehicle that lacks a motor is incomplete. > Q that cannot resolve (∀x, S(x) ≠ x) is complete > according to its definition. >