A deductive argument cannot be valid if:
2013
A deductive argument cannot be valid if:
Answer: B. If its premise / premises is /are true and its conclusion is false. — CONCEPTA deductive argument is valid exactly when there is no possible case in which all its premises are true and its conclusion is false. Validity concerns…
- A.
If its premise / premises is/are true and its conclusion is true.
- B.
If its premise / premises is /are true and its conclusion is false.
- C.
If its premise / premises is/are false and its conclusion is false.
- D.
If its premise / premises is / are false and its conclusion is true.
Show answer & explanation
Correct answer: B
CONCEPT
A deductive argument is valid exactly when there is no possible case in which all its premises are true and its conclusion is false.
Validity concerns the preservation of truth from premises to conclusion, not whether the statements happen to be true in the actual world.
APPLICATION
The combination “premise(s) true and conclusion false” is therefore the one truth-value pattern that a valid deductive argument cannot have. The other three combinations do not by themselves decide validity.
CONTRAST
True premises with a true conclusion can occur in a valid argument.
False premises with a false conclusion can occur in either a valid or an invalid argument.
False premises with a true conclusion can also occur in either a valid or an invalid argument.
RESULT
A deductive argument cannot be valid if its premise or premises are true and its conclusion is false.