Lesson 26: Testing Syllogisms by Rules Flashcards
How many rules are there for testing the validity of syllogisms?
Five rules.
What is the first rule for testing the validity of syllogisms?
In at least one premise, the middle term must be distributed.
What is the fallacy when the first rule is broken?
The Undistributed Middle
What is the second rule for testing the validity of syllogisms?
If a term is distributed in the conclusion, it must also be distributed in one of its premises.
What are the two names possible for the fallacy when the second rule is broken?
If the major term is distributed in the conclusion but not in the premise, the fallacy is known as The Fallacy of an Illicit Major.
If the minor term is distributed in the conclusion but not in the premise, the fallacy is known as The Fallacy of an Illicit Minor.
What is the third rule for testing the validity of syllogisms?
A valid syllogism cannot have two negative premises.
What is the fallacy when the third rule is broken?
The Fallacy of Two Negative Premises
What is the fourth rule for testing the validity of syllogisms?
A valid syllogism cannot have a negative premise and an affirmative conclusion.
What is the fallacy when the fourth rule is broken?
The Fallacy of a Negative Premise and an Affirmative Conclusion
What is the fifth rule for testing the validity of syllogisms?
A valid syllogism cannot have two affirmative premises and a negative conclusion.
What is the fallacy when the fifth rule is broken?
The Fallacy of Two Affirmative Premises and a Negative Conclusion
