Which logical form is valid? (1) If P then Q. Not P. Therefore not Q. (2) If P then Q. Not Q. Therefore not P.

A Only (1)

B Only (2)

C Both

D Neither

✓ Correct Answer: Option B

(1) is the fallacy of denying the antecedent. (2) is modus tollens — a valid form. If P→Q and Q is false, P must be false.

💡 Why is B) the correct answer?

The correct answer to the question "Which logical form is valid? (1) If P then Q. Not P. Therefore not Q. (2) If P then Q. Not Q. Therefore not P." is Option B: Only (2).

The other options — A) Only (1), C) Both, D) Neither — are incorrect for this LSAT Exam Prep question. As explained above: (1) is the fallacy of denying the antecedent. (2) is modus tollens — a valid form. If P→Q and Q is false, P must be false.

📚 About This LSAT Exam Prep Practice Question

This 2-level LSAT Exam Prep question from the Logical Reasoning topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free LSAT Exam Prep practice test or use flashcards for spaced repetition review.

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Which logical form is valid? (1) If P then Q. Not P. Therefore not Q. (2) If P then Q. Not Q. Therefore not P.

✓ Correct Answer: Option B

📚 About This LSAT Exam Prep Practice Question

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