A2 Categorical Syllogisms

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A2 Categorical Syllogisms

• A2.11 Rules and Fallacies

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Categorical Syllogisms

• There are 5 rules for and 5 corresponding
  fallacies that beset categorical syllogisms. They
  are
• The middle term must be distributed at least once
  (fallacy Undistributed Middle)
• All Tacos are Messy things
• All Sandwiches are Messy things
• All Sandwiches are Tacos
• All Messy things are Fun
• All Tacos are Messy things
• All Tacos are Fun
• If a term is distributed in the conclusion, it
  must be distributed in a premise (fallacies
  illicit major or illicit minor)
• Two negative premises are not allowed (fallacy
  Exclusive premises)
• A negative premise requires a negative
  conclusion, and a negative conclusion requires a
  negative premise (fallacies Drawing an
  affirmative conclusion from a negative premise or
  Drawing a negative conclusion from affirmative
  premises)
• If both premises are universal, the conclusion
  cannot be particular (fallacy existential
  fallacy)

T
T
S
F
M
M
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Testing Syllogisms by Rule

• Construct these syllogisms and test
• IAI-2
• EIO-1
• IEO-1
• EOO-4
• AII-3
• AAI-4