At the most recent debate Rick Santorum did show a little of this agility. While Ron Paul was attacking him the bell went off. When Paul paused Santorum interjected: “It caught you not telling the truth, Ron.”

Wit suggests an agile mind, which is useful for a president who needs to cut through complex subjects, rally people to a cause, or break the tension in negotiations. Given the polarization in Washington at the moment, perhaps wit is required more than ever. Peggy Noonan tells the story about Reagan, who listened while a reluctant senator explained why he wasn’t supporting a bill. “I’d jump out of a plane for you,” said the senator, testifying to his loyalty. Reagan responded, “Jump.” He got the vote. Among this year’s stock answers when Republican candidates are asked about bipartisanship and compromise is to cite Ronald Reagan’s cooperation with Democratic House Speaker Tip O’Neill. Their relationship was founded in part on joke telling.

And here’s a little tip for the candidates: It’s actually not that hard to tell jokes. You can just steal from Rep. Mo Udall. That’s what John McCain and Lamar Alexander did. “I’m Mo Udall and I’m running for president,” the failed Democratic candidate said, walking into a shop. “Yeah,” replied the barber, “we were just laughing about that.” (Though candidates repeat Udall’s best lines at their peril, like his observation that the difference between a cactus and a caucus is that with a cactus, the pricks are on the outside.)