Screwing with logic.

Discussion in 'Off Topic' started by Numerous, Feb 13, 2010.

  1. Numerous

    Numerous L4: Comfortable Member

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    So, I was bored, and having nothng else to do, I started screwing with logic. The following is what happens when you try it:
    "This sentence is true."
    Is that true or false? The obvious answer is true, but that's wrong. We can't really tell, default would be neither. But if we assume it's true, then it's true. If we assume it's false, then it's obviously false. So basically, it's potentially both. But something can't normally be both true and false, so which is it?

    It depends which you assume it is.. Except that has no actual effect on reality. No matter what we assume it is, it could be either. Because it is* both true and false, it's neither true nor false, but you can't change what it is because the sentence isn't dependent on anything.

    The point? I have no f:(king clue.
     
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  2. Leminnes

    aa Leminnes

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    the standard logic sentence that makes no sense is "This sentence is false."

    If the sentence is false then it's true but then it's false but then it's true... etc. etc.
     
  3. Numerous

    Numerous L4: Comfortable Member

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    Yes, but I'm talking about "this sentence is true", not "this sentence is false". See, if "this sentence is true" is true, then it's true. But if "this sentence is true" is false, then it's false. Wherease "this sentence is false" is false, then it's true, which means its false etc. And same thing for true.
    So basically:
    "this sentence is true" = both true and false, hypothetically.
    "this sentence is false" = inherently neither true nor false.

    Besides, I usually deal with "is the answer to this question no?", rather than "this sentence is false".
     
  4. Mexican Apple Thief

    Mexican Apple Thief L3: Junior Member<br>LEAD FARMER

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    It can't be false, it's true.
     
  5. Leminnes

    aa Leminnes

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    This, basically. In logic you don't really deal with if's, only is's.
     
  6. Numerous

    Numerous L4: Comfortable Member

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    It isn't true by default. Otherwise if I say "the bible is true" then I can use that to justify that if the bible says the bible is true, the bible must be true. This is known as "begging the question". Not that the bible is false, if you like you can replace "bible" with "Quran" (or Koran). And if we assume the statement "this sentence is true" is false, then as it says it's true but is actually false, it's false. Since both ways it's self-affirming, then I say it can be potentially either.
    Don't debate with me, I read university textbooks when I'm bored (the logic one was useful).

    PS: For some reason my iTouch capitalises "Quran" and "Koran" but not "bible".
    PPS: typing on an iTouch drives you crazy. The buttons are half the size of your finger, and in iTouch safari you can't rotate for a larger keyboard while typing on this forum.
     
  7. Lancey

    aa Lancey Currently On: ?????

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    I just heard that some guy named Isaac Newton discovered this new thing called Gravity.
     
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  8. gamemaster1996

    gamemaster1996 L13: Stunning Member

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    Please dont screw with any techno-logic :p
     
  9. A Boojum Snark

    aa A Boojum Snark Toraipoddodezain Mazahabado

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    Your bible thing doesn't have any weight to it. Logic is logic and only deals in facts, it cannot be held accountable for humans misusing it in ways that make it anything less than concrete (e.g. This sentence is false).
     
  10. Okrag

    aa Okrag Wall Staples

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    Oh snap! This thread just got Boojumed!
     
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  11. SPHinx

    SPHinx L2: Junior Member

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    "This sentence is true" is a straight-forward proposition. It is either true or false depending upon our semantic model.

    It gets more interesting if you use it in a conditional statement, like "If this sentence is true, then I can has cheeseburger." If "this is sentence is true" is true, then the entire conditional "If this sentence is true, then I can has cheeseburger" is only true if the consequent, "I can has cheeseburger" is also true. If "I can has cheeseburger" is false, then the conditional as a whole is false (so long as "this sentence is true" is true). And if "this is sentence is true" is false, then the conditional, no matter what the consequent, will always be true.

    The interesting thing, as has been noted, about "this sentence is false" is that it is neither true nor false. It is one of those peculiar cases in a language of a well-formed statement (i.e., a meaningful statement) in that language, yet it cannot be evaluated truth-functionally.
     
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  12. Lancey

    aa Lancey Currently On: ?????

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    Not to mention that logic can't be based on subjective fact.
     
  13. FaTony

    FaTony Banned

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    "This sentence is true" is true if we believe it and assume that it's truth. "This sentence is true" is false if we don't believe it and assume that it's lie. We have no other information about the sentence so we can't link this sentence with our beliefs so we can assume either case.

    Simple.
     
  14. Tapp

    Tapp L10: Glamorous Member

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    Congratulations, you just invented the NAND latch
     
  15. Numerous

    Numerous L4: Comfortable Member

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    If you assume something is true by default, then if I write a book that says "this entire book is true", then we can assume it's true and that means since it confirms its true, then it must be true. Circular logic. But the fact is, that's making an assumption and an unwarranted one.
    Besides, if we assume it's false then that means its false.
    I never said that it is true and false. I said it's potentially both true and false. If we make an assumption.
    Just because it states its true, doesn't mean it's true. It's like maths with square roots of squares, you can use straightforward logic and get one answer, but you've gotta go through the quadratic formula etc if you want to get both (and I'm thinking back a year or two here, i dont care if i've forgotten something in this analogy).

    Besides, you didn't actually explain how exactly my bible example "doesn't hold water".

    And by the way, this thread did NOT get Boojumed, he made unjustified assumptions and completely missed the point.
    Since FaTony actually got the picture, This thread just got FaTony'd.

    (screw past tense y>>~ied)
     
    Last edited: Feb 15, 2010