Validity and Soundness: Additional Exercises

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Validity and SoundnessAdditional Exercises

• 2007 Makoto Suzuki

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Validity and Soundness, once again

• Instructions For each of the following
  arguments, determine whether or not it is valid
  and whether or not it is sound.

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Question 1

• Gloria is an adolescent because all adolescents
  are grumpy and Gloria is grumpy.
• Valid or invalid?
• Invalid.
• This argument has the following fallacious
  argument form, where the capital letters are the
  variables that take general terms as values and a
  is a particular thing
• All F are G.
• a is G.
• a is F.
• Sound or unsound?
• Unsound
• Invalid arguments are necessarily unsound.

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Question 2

• Some Muslims are fundamentalists. Some
  fundamentalists are dangerous. Hence, some
  Muslims are dangerous.
• Valid or invalid?
• Invalid.
• Sound or unsound?
• Unsound.

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Question 3

• All wasps are unfriendly. No puppies are wasps.
  Therefore, no puppies are unfriendly.
• Valid or invalid?
• Invalid
• This argument has the following fallacious
  argument form
• All G are H. or No F are G.
• No F are G. All G are H.
• No F are H. No F are H.
• Sound or unsound?
• Unsound.

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Question 4

• Every upright person is believable. No man is
  believable. Therefore, no upright person is a
  man.
• Valid or invalid?
• Valid.
• This argument has the following valid argument
  form
• All F are G.
• No H are G.
• No F are H.
• Sound or unsound?
• Unsound.
• The second premise is false!