The question itself is useless. No politician EVER answers such a question.
McCain did ok, but my answer would be "Our Founding Fathers, inspired by God, created the greatest nation in the history of the world. If we just follow their ideals, I don't know how it can fail. The only way I might learn that would be if you, Sen. Biden, Sen. Harry Reid and Speaker Pelosi were granted the power to surrender that legacy."