1. (F • ∼ G) ⊃ H
2. J $ \lor $ F
3. ∼G • ∼I
4. ∼J / H $ \lor $ I
-Which of the following propositions is an appropriate assumption for an indirect proof of the conclusion of the given argument?
A) H $ \lor $ I
B) H • I
C) ∼H $ \lor $ ∼I
D) ∼H • ∼I
E) None of the above

Question

Quizplus · Accepted Answer

In an indirect proof, we assume the negation of the conclusion and try to derive a contradiction. Here, the conclusion is H $ \lor $ I, so we assume its negation, which is ∼(H $ \lor $ I) ≡ ∼H • ∼I. This matches with option D, so it is the best choice.

1 (F • ∼ G) ⊃ H 2 ∨ \lor ∨

1 (F • ∼ G) ⊃ H
2 $\lor$