Given the argument: M ⊃ Q / M ∨ ∼ Q // M • Q This argument is: A) Invalid; fails in 4^th line. B) Valid. C) Invalid; fails in 5^th line. D) Invalid; fails in 2^nd line. E) Invalid; fails in 3^rd line.

Question

Quizplus · Accepted Answer

The argument is invalid because it fails in the 4th line when using a truth table or logical derivation. The premises do not logically guarantee the conclusion. If M is false and Q is false, the premises are true (M ⊃ Q is true because a false antecedent makes a conditional true, and M ∨ ∼Q is true because ∼Q is true), but the conclusion M • Q is false, showing the argument can fail.

Given the Argument: M ⊃ Q / M ∨ ∼