Given the argument: H ⊃ G / G ⊃ H / H ∨ G // G • H This argument is: A) Invalid; fails in 1^st line. B) Invalid; fails in 6^th line. C) Invalid; fails in 3^rd line. D) Valid. E) Invalid; fails in 4^th line.

Question

Quizplus · Accepted Answer

The argument is valid because it follows the rule of hypothetical syllogism (if A implies B and B implies C, then A implies C) in the first two lines. The disjunction in the third line (H v G) does not affect the validity of the argument. And by using the conjunction elimination rule (if A and B are true, then A • B is true), we can conclude that G • H is true in the last line.

Given the Argument: H ⊃ G / G ⊃ H