1.4: Validity, Truth, Soundness, Strength, Cogency Flashcards
This section introduces the central ideas and terminology needed to evaluate arguments—to distinguish good arguments from bad arguments.
Deductive argument to…
Inductive argument to…
Validity, Strength
What two characteristics are associated to deductive and inductive arguments?
Think: “V and S…”
validity and strength
invalid, valid; strong, weak
What is a valid deductive argument?
it’s impossible for the conclusion to be false since the premises are true
What is an invalid deductive argument?
it is possible for the conclusion to be false since the premises are true
What is a sound deductive argument?
valid argument + true premises
What is an unsound deductive argument?
invalid argument + false premises
the false premise or premises must be needed to support the conclusion
What is a strong inductive argument?
the conclusion does follow from the premises, assuming they’re true
What is a weak inductive argument?
the conclusion doesn’t follow from the premises, assuming they’re true
What is a cogent argument?
strong argument + all true premises
What is an uncogent argument?
weak argument + no true premises
fails to meet total evidence requirement (TER)
Is this deductive argument valid or invalid?
All television networks are media companies.
NBC is a television network.
Therefore, NBC is a media company.
Valid
Is this deductive argument valid or invalid?
All banks are financial institutions.
Wells Fargo is a financial institution.
Therefore, Wells Fargo is a bank.
Invalid
Is this inductive argument strong or weak?
All dinosaur bones discovered to this day have been at least 50 million years old. Therefore, probably the next dinosaur bone to be found will be at least 50 million years old.
Strong
Is this inductive argument strong or weak?
Dom Pérignon champagne, which is made in France, sells for over $100 per bottle. Marquis de la Tour is also a French champagne. Therefore probably it, too, sells for over $100 per bottle.
Weak
