Given the argument: P ∨ J / ∼(J • ∼ P) // J ≡ ∼ P This argument is: A) Invalid; fails in 3^rd line. B) Invalid; fails in 2^nd line. C) Invalid; fails in 1^st line. D) Valid. E) Invalid; fails in 4^th line.

Question

Quizplus · Accepted Answer

The argument is invalid and fails in the 1st subproof where the assumption P is made and later J is derived. This is not a valid derivation as there is no justification for inferring J from P alone. Therefore, the argument cannot be valid.

Given the Argument: P ∨ J / ∼(J • ∼