• Re: Provability in PA --- Tarski "trivial" Wittgenstein"tautological" neither "true"

    From olcott@[email protected] to comp.theory,comp.ai.philosophy,sci.logic,sci.math on Sun Oct 11 20:19:01 2026
    From Newsgroup: comp.ai.philosophy

    On 10/11/2026 7:42 PM, Ross Finlayson wrote:
    On 10/11/2026 12:11 PM, Ross Finlayson wrote:
    On 10/11/2026 10:27 AM, olcott wrote:
    On 10/11/2026 11:36 AM, Ross Finlayson wrote:
    On 10/11/2026 06:00 AM, olcott wrote:
    On 10/11/2026 4:02 AM, Mikko wrote:
    On 06/10/2026 15:32, olcott wrote:
    On 10/6/2026 2:59 AM, Mikko wrote:
    On 04/10/2026 16:22, olcott wrote:
    On 10/4/2026 6:30 AM, Mikko wrote:
    On 02/10/2026 14:55, olcott wrote:
    On 10/2/2026 4:37 AM, Mikko wrote:
    On 01/10/2026 17:47, olcott wrote:
    On 10/1/2026 5:03 AM, Mikko wrote:
    On 29/09/2026 19:31, olcott wrote:
    On 9/29/2026 11:01 AM, Python wrote:
    No, Pete. Calling an undecidable sentence "out-of-scope" >>>>>>>>>>>>>>>> does not make undecidability disappear.

    For a formal theory T, "G is undecidable in T" simply means >>>>>>>>>>>>>>>>
        T |-/- G    and    T |-/- ~G

    That is a statement entirely about proofs. No model theory >>>>>>>>>>>>>>>> is involved.

    And G is not "out-of-scope": it is a perfectly well-formed >>>>>>>>>>>>>>>> sentence of the language of T. What is out-of-scope, >>>>>>>>>>>>>>>> apparently, is merely anything for which your proposed >>>>>>>>>>>>>>>> semantics fails to supply an answer.

    Within PTS any expression that is neither provable nor >>>>>>>>>>>>>>> refutable
    never acquires any semantic meaning.

    There is one more thing one needs to consider: there is no >>>>>>>>>>>>>> complete
    method to find out whether a sentence or its negation can be >>>>>>>>>>>>>> proven.
    Consequently, it is not possible to construct a system that >>>>>>>>>>>>>> rejects
    all undecidable sentences.

    If back-chained inference from expression X to axioms >>>>>>>>>>>>> has a loop it is rejected.

    Irrelevant. A direct proof is either a forward chain from >>>>>>>>>>>> premises
    to conclusion and an indirect proof is a similar chain from tne >>>>>>>>>>>> negation of the axioms and conclusion to a contradiction. >>>>>>>>>>>
    It turns out that automated proof systems expose
    the correct details the most clearly. They used
    back-chained inference. In any case when a finite
    canonical proof is impossible then the expression
    never gets semantically grounded.

    Existence of a proof and existence of a meaning are irrelevant to >>>>>>>>>
    The Goldbach conjecture is meaningful yet its truth value will be >>>>>>>>> unknown unless and until it proof can be algorithmically
    compressed.

    It truth value will be known as soon as its proof has been
    chekcked and
    found good. The proof can be algorithmically compressed as soon as >>>>>>>> it is
    found, even before the verification, though that is irrelevant to >>>>>>>> the
    knowledge of its truth. Thought it is possible that it will be >>>>>>>> found to
    be unprovable. But none of that affects its meaning and
    meaningfulness.
    What PTS says about its meaning is irrelevant.

    A finite proof might not exist.
    It may forever remain unknowable
    thus outside of the domain of knowledge.

    That is one possibility, as already noted above. But it is also
    possibe that a finite proof exists and is knowable but remains
    forever unknown.


    My 28 year goal has been to make
    "true on the basis of meaning expressed in language"
    reliably computable for the entire body of general knowledge.
    Anything unknown for any reason is not a member of the body of
    knowledge.

    However, these possibilities are irrelevant to the meaning of the
    of the conjecture, which we do know in spite or our ignorance of
    its provability and truth value.

    It might be the case that its truth value is unknowable.

    It even might be possible that we can't ever know whether its truth >>>>>>>> value is unknowable.

    I restricted my system to "the body of general knowledge that >>>>>>>>> can be
    expressed in language" to handle these edge cases.

    Then your system needs be updated when something unknonw becames >>>>>>>> known.

    It is updated the same way that Pluto ceased to be a planet.

    It is not updated unless somebody updates it. Also note that the
    process
    that resulted to Pluto not being regarded as a planet was not simple >>>>>> and
    easy.


    If no human mind knows a thing then it is outside
    the body of knowledge.

    each other. For example, the sentence ∀x ∀y (x * y = y * x) is >>>>>>>>>
    The Commutative Law For Multiplication
    https://en.wikiversity.org/wiki/Basic_Laws_of_Algebra

    meaningful in many theories and provable in some of them and >>>>>>>>>> unporvable others.

    That is merely a limitation of the individual formal systems. >>>>>>>>
    Being meaningful is not a limitation, nor is the ability to prove >>>>>>>> that the commutativity law is false.


    It is true, so that any attempt at proving that
    it is false is incorrect.

    Meaningless expressions are outside the body of knowledge.

    The commutativity law is not meaningless, whther provable or not.

    My focus has always been on "the body of general knowledge
    that can be expressed in language".

    That should include the meanings of the commutativity law and its
    negation nad that in some cases both are unprovable but meaningful. >>>>>>

    a mathematical property where changing the order of
    the operands does not change the final result.

    The proof that feline cats are a type of 15 story
    office building comes up empty because it is false.

    I never really cared that system X is too weak to fully express Y. >>>>>>
    Then you should not post to this discussion as its topic is whether >>>>>> PA is too weak to fully express the proof of G.


    On the Relation Between Heyting’s
    and Gentzen’s Approaches to Meaning
    Dag Prawitz (2013)

    "Gentzen’s idea could be summarized by saying that
    the meaning of a sentence is determined by what
    counts as a canonical proof of it..."

    https://doi.org/10.1007/978-3-319-22686-6_2
    This is the way that
    "true on the basis of meaning expressed in language"
    has always worked in actual reality.

    A weaker system has a larger scope of applications, which is often >>>>>>>> quite useful.


    counter-factual. "Weaker" is stipulated to mean a reduced scope.

    No, "stronger" is stipualted to mean a reduced scope, i.e., greater >>>>>> ability to exclude from the scope what is not wanted.

    For example, it is not provable in a group
    (where its negation isn't, either) nor in the quaternions (where >>>>>>>>>> its negation is provable) but it is meaningful in both.

    For
    "true on the basis of meaning expressed in language"
    when an expression cannot possibly connect to the
    expressions that give it meaning then it never gets
    any meaning.

    That is not the basis in the above examples.

    *This is the domain of my proposed system*
    "the body of general knowledge that can be expressed in language" >>>>>>>>
    Irrelevant to your attempt to deceive with an ireelevancy.

    If all words are defined in terms of other words and
    there is a string of symbols that it never assigned
    any relation to other strings then it remains meaningless. >>>>>>>>>>
    They are also meaningless if there are diretly or indirectly >>>>>>>>>> circular definitions.

    Like the cycle in the directed graph of the evaluation sequence >>>>>>>>> of the Liar Paradox formalized in Prolog.

    Quite unlike. Circular definitions don't define. A cyclic
    evaluation
    graph

    Never terminates thus never derives PTS semantic meaning.

    Irrelevant. A cyclic evaluation graph is not meaningless. A circular >>>>>> definition does not present a meaning.

    On the Relation Between Heyting’s
    and Gentzen’s Approaches to Meaning
    Dag Prawitz (2013)

    "Gentzen’s idea could be summarized by saying that
    the meaning of a sentence is determined by what
    counts as a canonical proof of it..."

    https://doi.org/10.1007/978-3-319-22686-6_2

    This is the way that
    "true on the basis of meaning expressed in language"
    has always worked in actual reality.




    It's a formal fact that any declaration has at least two readings,
    for examples, one where it's true and one where it's not, and for
    a wider example, one where it's true for itself (the usual "tau-
    tology")
    and one where it's as for "cosmic complement" given
    an actual account of formal identity (the less-than-usual "identity"). >>>>


    So its true that 5 equals 6 has more than one
    correct truth value?

    Then, for examples, a declaration is all the questions it answers,
    implicitly with all the other declarations (and all the other
    questions).

    Questions may stay the same temporally, declarations their answers
    change, with the times.


    What's "true" is what remains invariant under alternatives,
    tests and examinations, all the space of questions, all the
    space of declarations, sentences with meaning are re-readable.



    So, accounts of meaning or _significance_ vis-a-vis something like
    Russell's "isolation" and "significance", about the signification
    of statements, makes for mechanics in informatics and accounts of
    work, then for both what statements "prove" or what can be inferred
    from them, _and_ what "prove" them.


    Then, "the meaning" of a declaration about the relate-able,
    talking to yourself, then the relay-able, convey-able to others,
    makes for that there's always again _another_ layer of meaning,
    about the utterances and the utterers, and the audience, _another_
    layer, point being usual accounts about "Sowa" and so on are
    navel-gazing of the monomaniac variety.



    Too convoluted for yo top show that you understand
    the exact meaning of my words.


    Really, lots of people reject and refuse "Tarski-trivial" or
    "Wittgenstein-tautological" when it comes to "true",
    Tarski as trivial, Wittgenstein as tautological.


    There was a time when there was a universal consensus
    that the Earth was flat.

    There's Sheffer and Chwistek, and Huntington's universals, ....



    In Tarski's theory of a flat earth it's flat,
    and Wittgenstein says it doesn't matter anyways,
    due _a priori_ truths like "a strict inequality
    exists in ordinals as modeled by finite natural
    integers" that "5 < 6 and 5 =/= 6 is a fact"
    still has, for example, that neither five wrongs
    nor six wrongs is anyways right.


    Wittgenstein is a liar whose great contribution
    to liars is "don't break the spell", Tarski is
    a tabulator who has run out of fingers.


    The "invincible ignorance of inductive inference"
    is readily dis-spelled by deductive reasoning.



    The polaricentric and other accounts of deductive
    reasoning about space and space-time in the universals
    and wider Mach-ian and wider LaGrange-ian is a sort of
    ultimate refutation of "Flat-Earth".


    Statements and declaration and interrogatives and
    question in our rich natural language readily make
    for that it's a formal fact that while transliterations
    of words already have a "number", which is readily enough
    their letters in their alphabet the word, they also have
    a number that is infinite.


    Matters of motion and continuity and other accounts of
    ultimate universals make it so your mis-reading of Goedel
    and Prawitz and so on then the ostrich-heading is bull-shit.


    Quit trying, or change your ways.




    Wittgenstein says things like "you can't talk about what's
    not given in my theory" then "no-one can understand what
    you say in your theory",

    I never paid any attention to anything he ever said besides
    his exact agreement with the same analysis of Incompleteness
    that I independently derived before I ever heard of him.
    The record of this is on sci.logic

    https://www.liarparadox.org/Wittgenstein.pdf

    That the foundation of Proof Theoretic Semantics proves
    that he has always been correct within this alternative
    foundation is something new to me in 2026.

    these are logically insane and
    marks of a liar and abuser of language.


    Now, a lot of people find it liberating to latch onto something that Wittgenstein says as giving them free-will when it's perceived accounts
    like "determinism" or "natural order" or for that matter "positivism"
    or even "nominalism" or "nominalist fictionalism" get in the way,
    yet nobody needs Wittgenstein's permission or lack thereof for anything.


    Tarski is the type to try to make a model of a logical theory
    that you can only follow not change. He failed trying to prove
    he could make one.
    --
    Copyright 2026 Olcott

    The essence of computation is applying finite
    string transformations to finite string inputs
    to derive outputs. // paraphrase of Emil Post

    My 28 year goal has been to make
    "true on the basis of meaning expressed in language"
    reliably computable for the entire body of general knowledge.
    The complete structure of this system is now defined.

    The entire body of knowledge expressed in language is
    comprised of two types of relations between finite strings:
    (a) *Axioms* Expressions of language that are stipulated to be true.

    My system bridges the analytic/synthetic distinction by
    expressly encoding all empirical "atomic facts" in a formal
    language such as CycL of the Cyc project.

    (b) *Inference Rules* Expressions of language that are semantically
    entailed syntactically from (a) and/or (b).
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