View Poll Results: Is the argument logically valid?

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  • No, the argument is not logically valid.

    3 37.50%
  • Yes, the argument is logically valid.

    5 62.50%
  • I don't know.

    0 0%
  • The question doesn't make sense.

    1 12.50%
  • The argument doesn't make sense.

    0 0%
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Thread: Everyone is female... Therefore ... ?

  1. Top | #11
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by Politesse View Post
    Quote Originally Posted by Speakpigeon View Post
    Here is an interesting logical argument:

    Everyone is female;
    Therefore, any siblings are sisters.
    Do you personally think this argument is logically valid?

    Thank you to cast a vote before posting any comment.

    Please note you can vote for several options.
    EB
    Well, we all start our lives as biological sisters to our siblings, anatomically speaking. But I assume you were after philosophical, not empirical, validation.
    I didn't say "philosophical validity". I said "logical validity". Is the argument logically valid do you think?

    Can you explain why you voted "the question doesn't make sense"?
    EB

  2. Top | #12
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by fromderinside View Post
    Quote Originally Posted by Speakpigeon View Post

    Everyone is female;
    Therefore, any siblings are sisters.

    EB
    No.

    It fails logical limitation necessary to attribute everyone group. Is it everyone present is female, everyone everywhere are female? If it is everyone observed is female then then are the siblings product of the females present only? and are all the siblings of one parent or are the siblings are just those found in a group that was all female with other females who may have been mothers, grandmothers, daughters, or granddaughters.
    The premise "Everyone is female" does"t read "Everyone present is female".

    The premise "Everyone is female" does"t read "Everyone observed is female".

    The premise "Everyone is female" just reads "Everyone is female".

    Maybe I should put that in bigger size.
    EB

  3. Top | #13
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by fast View Post
    the technical terms’ technical usage often trumps common usage when the discussion pertains to a technical field.
    Sure, but "often trumps" won't be enough here.

    And you would have to justify your implicit notion here that mathematical logic is the correct way to do logic as people not trained in mathematical logic think of it. I think I have demonstrated it's not.

    Consequently, there is zero good reason to use mathematical logic's notion of validity when discussing logic.

    Quote Originally Posted by fast View Post
    A sound argument is a valid argument with true premises. That’s how it’s used by trained logicians. Coming in and using it like the everyday dictionary explains its usage intentionally creates ambiguity where there should be none.

    Validity doesn’t imply soundness whereas soundness implies validity — in accordance to technical usage.

    A sound argument is superior to an argument that is merely valid.
    That's entirely irrelevant to this thread since I asked about validity. It is also entirely irrelevant to my comment to DBT. I hope you're not suggesting DBT is confused about soundness and validity?

    I use the term "soundness" as most people understand it and we all understand enough of the difference between sound and valid to talk competently about it. And that's what I'm interested in anyway.

  4. Top | #14
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    You asked “is the argument logically valid?”

    When you specifically use the term “logically” to describe a particular sense of validity when discussing an argument, not only will Larry, Curly, Moe, Shemp, and Joe refrain from using “valid” in a layman sense as explained in dictionaries, they will (like most all logicians) turn to a glossary specific to the field of logic as used by those who study logic.

    ‘Logic’ need not even resemble “logic.” ‘Valid’ need not resemble “valid.”

  5. Top | #15
    Mazzie Daius fromderinside's Avatar
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    Quote Originally Posted by Speakpigeon View Post

    The premise "Everyone is female" just reads "Everyone is female".

    Maybe I should put that in bigger size.
    EB
    Ah the reason I left out because it is so obvious that I constructed instances for possibly logical true applications of everyone is female. It is demonstrably false that Everyone is female which would make you last comment really embarrassing for you. If it is demonstrably false it cannot be logically true.

  6. Top | #16
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    The conclusion doesn't follow from the premise. "Everyone" means "every person". "Sibling" means "one of two or more individuals having one common parent", not "one of two or more individual persons having one common parent". So everyone being female doesn't imply ducks don't have brothers.

  7. Top | #17
    Contributor DBT's Avatar
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    Maybe in that little universe all males were killed off and females took up the practice of cloning.....consequently, 'everyone is female?'

  8. Top | #18
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by fromderinside View Post
    Quote Originally Posted by Speakpigeon View Post

    The premise "Everyone is female" just reads "Everyone is female".

    Maybe I should put that in bigger size.
    EB
    Ah the reason I left out because it is so obvious that I constructed instances for possibly logical true applications of everyone is female. It is demonstrably false that Everyone is female which would make you last comment really embarrassing for you. If it is demonstrably false it cannot be logically true.
    How can you be so utterly ignorant?

    Still, I didn't ask whether the premise was true, or indeed "*logically true*", whatever you may mean by that.

    I ask about the argument, and I asked whether it was *logically valid*, not whether it was logically true.

    But I guess your answer goes a long way to explain how you don't understand anything I say.
    EB

  9. Top | #19
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by DBT View Post
    Maybe in that little universe all males were killed off and females took up the practice of cloning.....consequently, 'everyone is female?'
    DBT 1 - FDI 0.
    EB

  10. Top | #20
    Contributor Speakpigeon's Avatar
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    Quote Originally Posted by fast View Post
    You asked “is the argument logically valid?”

    When you specifically use the term “logically” to describe a particular sense of validity when discussing an argument, not only will Larry, Curly, Moe, Shemp, and Joe refrain from using “valid” in a layman sense as explained in dictionaries, they will (like most all logicians) turn to a glossary specific to the field of logic as used by those who study logic.
    LOL. This is preposterous. You are talking from ignorance.

    Beside, you can see for yourself that Joe does use "valid" to refer to logical validity. Everybody does. You should try it.

    You keep up the pretence that logic is only mathematical logic. Aristotle came 2,300 years before any mathematical logic and described logic as he saw it in the argument of philosophers at the time and indeed in the way people in general used language.

    Quote Originally Posted by fast View Post
    ‘Logic’ need not even resemble “logic.” ‘Valid’ need not resemble “valid.”
    Indeed.

    I just realised you don't argue.
    EB

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