What is the rule of inference by which the conclusion of this argument follows from the premise?
C ? (A ? B)
? C ? (~~A ? B)
A)distribution
B)double negation
C)addition
D)constructive dilemma

Question

What is the rule of inference by which the conclusion of this argument follows from the premise?
C ? (A ? B) 
? C ? (~~A ? B)
A)distribution
B)double negation
C)addition
D)constructive dilemma

Quizplus · Accepted Answer

The rule of inference used here is double negation, which allows the removal or introduction of double negatives. In this case, "~~A" is equivalent to "A", making the statements logically equivalent.

What Is the Rule of Inference by Which the Conclusion