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|    Message 262,881 of 262,912    |
|    olcott to Mikko    |
|    Re: Making all knowledge expressed in la    |
|    13 Feb 26 07:32:25    |
   
   XPost: sci.math, comp.theory   
   From: polcott333@gmail.com   
      
   On 2/13/2026 2:30 AM, Mikko wrote:   
   > On 12/02/2026 17:48, olcott wrote:   
   >> On 2/12/2026 2:11 AM, Mikko wrote:   
   >>> On 11/02/2026 14:38, olcott wrote:   
   >>>> On 2/11/2026 4:51 AM, Mikko wrote:   
   >>>>> On 10/02/2026 15:37, olcott wrote:   
   >>>>>> On 2/10/2026 3:06 AM, Mikko wrote:   
   >>>>>>> On 09/02/2026 17:36, olcott wrote:   
   >>>>>>>> On 2/9/2026 8:57 AM, Mikko wrote:   
   >>>>>>>>> On 07/02/2026 18:43, olcott wrote:   
   >>>>>>>>>>   
   >>>>>>>>>> Conventional logic and math have been paralyzed for   
   >>>>>>>>>> many decades by trying to force-fit semantically   
   >>>>>>>>>> ill-formed expressions into the box of True or False.   
   >>>>>>>>>   
   >>>>>>>>> Logic is not paralyzed. Separating semantics from inference rules   
   >>>>>>>>> ensures that semantic problems don't affect the study of proofs   
   >>>>>>>>> and provability.   
   >>>>>>>>   
   >>>>>>>> Then you end up with screwy stuff such as the psychotic   
   >>>>>>>> https://en.wikipedia.org/wiki/Principle_of_explosion   
   >>>>>>>   
   >>>>>>> That you call it psychotic does not make it less useful. Often an   
   >>>>>>> indirect proof is simpler than a direct one, and therefore more   
   >>>>>>> convincing. But without the principle of explosion it might be   
   >>>>>>> harder or even impossible to find one, depending on what there is   
   >>>>>>> instead.   
   >>>>>>   
   >>>>>> Completely replacing the foundation of truth conditional   
   >>>>>> semantics with proof theoretic semantics then an expression   
   >>>>>> is "true on the basis of meaning expressed in language"   
   >>>>>> only to the extent that its meaning is entirely comprised   
   >>>>>> of its inferential relations to other expressions of that   
   >>>>>> language. AKA linguistic truth determined by semantic   
   >>>>>> entailment specified syntactically.   
   >>>>>>   
   >>>>>> Well-founded proof-theoretic semantics reject expressions   
   >>>>>> lacking a "well-founded justification tree" as meaningless.   
   >>>>>> ∀x (~Provable(T, x) ⇔ Meaningless(T, x))   
   >>>>>   
   >>>>> Usually it is thought that an expression can be determined to be   
   >>>>> meaningful even when it is not known whether it is provable. For   
   >>>>> example, the program fragment   
   >>>>>   
   >>>>> if (x < 5) {   
   >>>>> show(x);   
   >>>>> }   
   >>>>>   
   >>>>> is quite meaningful even when one cannot prove or even know whether   
   >>>>> x at the time of execution is less than 5.   
   >>>>>   
   >>>>   
   >>>> Only Proof-Theoretic Semantics   
   >>>> https://plato.stanford.edu/entries/proof-theoretic-semantics/   
   >>>>   
   >>>> Can make   
   >>>> "true on the basis of meaning expressed in language"   
   >>>> reliably computable for the entire body of knowledge.   
   >>>   
   >>> In order to achieve that all arithmetic must be excluded from   
   >>> "true on the basis of meaning expressed in language". There   
   >>> is no way to compute wheter a sentence of the first order   
   >>> Peano arithmetic is provable.   
   >>   
   >> ∀x (Provable(T, x) ⇔ Meaningful(T, x)) --- (Schroeder-Heister 2024)   
   >> ∀x (Provable(x) ⇒ True(x)) --- Anchored in (Prawitz, 2012)   
   >>   
   >> What is the appropriate notion of truth for sentences whose meanings   
   >> are understood in epistemic terms such as proof or ground for an   
   >> assertion? It seems that the truth of such sentences has to be   
   >> identified with the existence of proofs or grounds...   
   >   
   > Which means that if it is not determined whether there is a proof of   
   > a sentence and no way to find out the truth of that sentence is not   
   > known and cannot be computed.   
   >   
      
   Its all in a finite directed acyclic graph of knowledge.   
   If a back-chained inference does not exist from x to the   
   axioms of T then then x does not have a well-founded   
   justification tree and is rejected as meaningless.   
      
   When a cycle in the inference chain is detected this   
   also proves x does not have a well-founded justification   
   tree and is rejected as meaningless.   
      
   This gets rid of all pathological self-reference such   
   as the liar paradox and the halting problem proof.   
      
      
   --   
   Copyright 2026 Olcott
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