Can a sentence be both true and false in the same sense? - Dialetheism

It might seem nonsensical until one sees the liar’s paradox:

This sentence is false.

Using classical logic, this sentence seems to be both true and false. Due to the explosion rule, that implies every sentence. This is absurd, but philosophers don’t agree on what has gone wrong here.

Dialetheism is the solution that accepts that it is both true and false and modifies logic to exclude the principle of explosion

@general

  • P00ptart@lemmy.world
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    3 days ago

    It’s not a logical issue because the sentence itself is nonsense. There’s no information in it and isn’t proper English. If you have to break a language to invent a paradox, then it likely isn’t worthy of consideration to begin with.

    • CrayonRosary@lemmy.world
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      2 days ago

      Nothing you said is true.

      1. Nonsense. False.
      2. No information. False.
      3. Improper English. False.

      This is a very well known sentence that leads to things like Gödel’s Incompleteness Theoreom.

      If you don’t enjoy the philosophy of logic, that’s fine, but don’t go saying a very famous sentence is improper English.

    • J Lou@mastodon.socialOP
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      3 days ago

      There is information in it. Namely, that it itself is false. It is fully grammatical. Similar sentence are obviously valid such as:

      This sentence has five words.

      That is a true valid grammatical sentence.

      I didn’t invent the paradox. Philosophers have been contemplating this paradox for a long time.

      The problem it gestures at is very deep and similar paradoxes showed up in the foundations of mathematics in the 20th century. It can’t be dismissed easily.

      @general

      • P00ptart@lemmy.world
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        2 days ago

        The sentence refers to a fact that can be true or false, but doesn’t refer to any fact in and of itself. Nobody would ever use this sentence outside of grading papers. So the one sentence is grammatically incorrect because it refers to nothing. It’s a waste of thought.