Given the argument: R ⊃ (G • D) / N ⊃ (A • L) / R ∨ N / L ⊃ K // D • K
This argument is:
A) Uncogent.
B) Sound.
C) Invalid.
D) Valid.
E) Cogent.

Question

Quizplus · Accepted Answer

The argument is invalid. 
To see this, suppose the premises are true while the conclusion is false. We need R ∨ N to be true, but both of its disjuncts, R and N, lead to false conclusions as shown below:
- If R is true, then (G • D) must be true, but this doesn't guarantee that D • K is true since K may or may not be true.
- If N is true, then (A • L) must be true, but this doesn't guarantee that D • K is true since D may or may not be true.

Given the Argument: R ⊃ (G • D) / N