[(G • H) ⊃ I] ⊃ [G ⊃ (H ⊃ I)]
Which of the following propositions is a proper assumption for conditional proof to prove that the above wff is a logical truth of PL?
A) [(G • H) ⊃ I] ⊃ [G ⊃ (H ⊃ I)]
B) [(G • H) ⊃ I] ⊃ (G ⊃ H)
C) [(G • H) ⊃ I] ⊃ G
D) (G • H) ⊃ I
E) G • H

Question

Quizplus · Accepted Answer

To use conditional proof to prove [(G • H) ⊃ I] ⊃ [G ⊃ (H ⊃ I)] as a logical truth of PL, we need to assume its antecedent, which is (G • H) ⊃ I. Therefore, choice D is the proper assumption for this conditional proof. The other choices do not provide the necessary assumption for the proof.