Validity And Soundness - Practice Exercises

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| By Jlschwenkler
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Validity And Soundness - Practice Exercises - Quiz

Determine whether each of the following arguments are VALID and/or SOUND. Remember: A valid argument is one whose conclusion is guaranteed if we assume that its premises are true, and a sound argument is one that is valid and also has true premises.


Questions and Answers
  • 1. 

    Either President Lincoln was assassinated, or he was killed in an accident. President Lincoln was not killed in an accident. Therefore, President Lincoln must have been assassinated.

    • A.

      Check here if the argument is VALID.

    • B.

      Check here if the argument is SOUND.

    • C.

      Check here if the argument is NEITHER valid NOR sound.

    Correct Answer(s)
    A. Check here if the argument is VALID.
    B. Check here if the argument is SOUND.
    Explanation
    This argument is both valid AND sound: it is valid because the truth of the premises guarantees the truth of the conclusion (the first premise gives you two options, the second premise rules one of them out, and the conclusion chooses the other of the two); and it is sound because in addition to being valid the argument also has true premises.

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  • 2. 

    Either Princess Diana was assassinated, or she was killed in an accident. Princess Diana was not killed in an accident. So Princess Diana must have been assassinated.

    • A.

      Check here if the argument is VALID.

    • B.

      Check here if the argument is SOUND.

    • C.

      Check here if the argument is NEITHER valid NOR sound.

    Correct Answer
    A. Check here if the argument is VALID.
    Explanation
    This argument is valid but NOT sound: it is valid because the truth of the premises guarantees the truth of the conclusion (the first premise gives you two options, the second premise rules one of them out, and the conclusion chooses the other of the two); and it is unsound because Princess Diana was not *actually* assassinated, but rather was killed in a car crash.

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  • 3. 

    It is January. January is in the wintertime. So it must be winter.

    • A.

      The argument is VALID.

    • B.

      The argument is SOUND.

    • C.

      The argument is NEITHER valid NOR sound.

    Correct Answer
    A. The argument is VALID.
    Explanation
    This argument is valid, but NOT sound: it is valid because if it *were* January, then given that January's in the wintertime it would follow that it's winter; but it's unsound because it's not actually January.

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  • 4. 

    It is February.February is in the wintertime.So it must be snowing.

    • A.

      Check here if the argument is VALID.

    • B.

      Check here if the argument is SOUND.

    • C.

      Check here if the argument is NEITHER valid NOR sound.

    Correct Answer
    C. Check here if the argument is NEITHER valid NOR sound.
    Explanation
    This argument is neither valid NOR sound: the premises might make the conclusion *more likely*, but they don't *guarantee* that it's true, as of course it doesn't snow on every winter day in February.

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  • 5. 

    February 17th is Ash Wednesday.February 17th is this Wednesday.So this Wednesday must be Ash Wednesday.

    • A.

      Check here if the argument is VALID.

    • B.

      Check here if the argument is SOUND.

    • C.

      Check here if the argument is NEITHER valid NOR sound.

    Correct Answer(s)
    A. Check here if the argument is VALID.
    B. Check here if the argument is SOUND.
    Explanation
    This argument is both valid AND sound: the premises are true, and given what they say the conclusion has to follow; if the 17th is Ash Wednesday and this Wednesday is the 17th, then this Wednesday has got to be Ash Wednesday.

    Rate this question:

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  • Current Version
  • Jan 24, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Feb 15, 2010
    Quiz Created by
    Jlschwenkler
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