• BB100
    107
    As far As I been researching Intuitionistic logic does not use True or false values, Denies Law of excluded middle, and Has the True and not provable system. From these I got that it does not accept proof by contradiction, pierce law, -(-p)=p, and such. Seems so far, this axiomatic system conflates ability to actively prove and Truth together. Anyone able to inform me more, for I intend to have a discussion about how The Three Classical laws are true, therefore anything others that conflict is not true.
  • I like sushi
    4.3k
    For those interested there is more information here:

    https://plato.stanford.edu/entries/logic-intuitionistic/
  • BB100
    107
    I have a question, since intuitionistic logic stems from a mathematical. Axiom, does it not mean from Godel's Incompleteness Theorem that it cannot prove everything itself?
  • tim wood
    8.7k
    edit: incomplete post posted by accident, deleted
  • tim wood
    8.7k
    Seems so far, this axiomatic system conflates ability to actively prove and Truth together.BB100

    Can you make that a little clearer? Within certain given systems truth and provability are not identical, but it's not categorically true across systems, or in subsequently expanded systems. This material is very sensitive to definitions - I'm not asking. But clarification where needed is good.
  • BB100
    107
    What I mean is it says what is true if you can prove it and if not then not priveable. The condition of truth is dependant on provability in a sense.
  • A Seagull
    615
    90

    What I mean is it says what is true if you can prove it and if not then not priveable. The condition of truth is dependant on provability in a sense.
    BB100

    So how come you apply (in the other thread) truth to the 3 laws of logic, which are unproven?
  • BB100
    107
    I mentioned before that The three laws are neccessarily come from meaning of truth, what is.
  • aletheist
    1.5k

    If you need to understand intuitionistic logic better in order to argue against it effectively, how do you already know that you will want to argue against it once you do better understand it? Perhaps understanding it better will lead you to realize that it makes perfect sense on its own terms, even though it is inconsistent with classical logic--which, by the way, absolutely no one denies. Everything that conforms to intuitionistic logic also conforms to classical logic, but certain results of classical logic do not obtain in intuitionistic logic. In that sense, it is a more modest formal system, like non-Euclidean geometry relative to Euclidean geometry--one fewer axiom.
  • TheMadFool
    13.8k
    Is this another Wittgensteinian moment? Language games complicating an already confusing and overcrowded landscape of ideas?
  • A Seagull
    615
    I mentioned before that The three laws are neccessarily come from meaning of truth, what is.BB100

    Well that is entirely illogical.
  • Eli
    4
    Hey does anyone have the time to help me out with a simple logic problem really quick???
  • tim wood
    8.7k
    What I mean is it says what is true if you can prove it and if not then not priveable. The condition of truth is dependant on provability in a sense.BB100

    That is, if not true then not provable? I think you've got yourself tangled up. If not true propositions were provable, then you run into what's called explosion, in this context meaning that everything is provable.

    Maybe you mean that you think what "they're" saying is that if not provable, then not true. But Godel's theory hinges on there being a lot of unprovable propositions that can be known to be true by what's called meta-mathematical reasoning.
  • BB100
    107
    Yes, that is what I mean.
  • BB100
    107
    The simple fact that proof by contradiction is not accepted as valid, even though the result must be true. Inherently the axiomatic system is focused on proof results that specifies an object. I know that the system accepts Law of Excluded Middle over a finite set boundaries, but not over an infinity. Last reason is because the system is based on pire mathematical concepts. The Three Laws are based independant to such and thus between them is the implications of The three laws are more overarching.
  • tim wood
    8.7k
    Consider a reboot? What exactly are you asking?

    You can if you like argue the three rules are true, but then you shall have to give a definition of true. i do not think that what you come up with there will be satisfying, nor be what you're looking for.
  • tim wood
    8.7k
    I know that the system accepts Law of Excluded Middle over a finite set boundaries, but not over an infinity.BB100
    This an example of the problems you're looking at. Let me try a metaphor. "If I had an infinite amount of money, I could buy anything. But I do not, therefore there are things I cannot buy." Question: how much does the thing you cannot afford cost? You see the problem, yes?
  • BB100
    107
    Sorry, Grammar is still not the best.

    Truth is defined and I assume is defined as what is, or another way of saying, what exists.

    What exists must be in compliance to the three laws. You can extrapolate the three laws from the very concept of the meaning exist.
  • BB100
    107
    First I would ask whether that money is tradable in the currency exchange system, then say that question requires emperical evidence to solve.
  • tim wood
    8.7k
    Truth is defined and I assume is defined as what is, or another way of saying, what exists.
    What exists must be in compliance to the three laws. You can extrapolate the three laws from the very concept of the meaning exist.
    BB100
    The stone in my backyard is truth, or the truth, or a truth? That won't do. If truth is things, and all things differ, then truth is far and away a many. Is that where you want to go?

    First I would ask whether that money is tradable in the currency exchange system, then say that question requires emperical evidence to solve.BB100
    The idea here is that once you indicate a price, then someone with a non-infinite amount of money could buy it. The point being that the logic of the infinite gets strange, different, and non-intuitive. What works here doesn't work there; and there not here. All in the way of showing that if a question generates a lot of do you mean this or that, then the question needs work. Which is to say that if it's a question that's any good, it needs to be approached before it can be asked.
  • BB100
    107
    Sorry, still need to check before posting to see If I wrote something correctly.

    But, "The stone in your backyard", I would say needs to be said as There is the stone in your backyard. This would be a truth. Just stone would not provide any distinction of what you are saying.

    Infinity is more so a concept, so it would not be strange that something that is true such as in a finite system , to not apply in a non finite system. Infinite Hotel being an example, full but can hold more people.
  • tim wood
    8.7k
    There is the stone in your backyard. This would be a truth. Just stone would not provide any distinction of what you are saying.BB100
    Contrast this with your "Truth is defined and I assume is defined as what is, or another way of saying, what exists."

    I think you have moved from the stone as truth to the proposition expressing something true about this stone here. A big jump, and nothing about truth where we've landed.
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