What is the contrapositive of a general statement 'If P then Q'?

• A. If not Q then not P
• B. If P then Q
• C. If Q then P
• D. If not P then not Q

Answer: (C)

The main idea is that the contrapositive of a conditional preserves truth by swapping and negating both parts. For "If P then Q," the contrapositive is "If not Q, then not P." This version is true exactly when the original statement is true, so they always share the same truth value. That equivalence is what makes the contrapositive a reliable way to reason about conditionals.

This differs from the converse, which would be "If Q then P," and the inverse, which would be "If not P then not Q." Neither of those forms necessarily has the same truth value as the original.