Why is this crop of presidential candidates so incredibly unfunny?

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.)

You can go too far, of course. James Garfield's political adviser warned him against humor—"Never make the people laugh. If you would succeed in life you must be solemn, solemn as an ass."  Herman Cain used humor so much to dodge questions that it was unsettling. That joke about not knowing the name of foreign leaders isn't that funny if polls consistently show that voters think you're incapable of handling a foreign policy crisis or managing the serious duties of the Oval Office.

My characterization of the current field may be slightly unfair to Newt Gingrich, who has been known to offer some humor. At a rally in Wolfeboro he signed a photograph from a voter named "Slim," then said, "Nobody has ever called me slim." At the last debate he said he was struggling to hold his tongue so as not to appear "zany," a wry reference to a dig by Mitt Romney. But Gingrich is so busy calling people stupid and adopts such a lecturing tone it may be harder to hear the humor in his pitch. And the bile in some of his jokes may sap their effectiveness. When he said Michelle Bachmann was "factually challenged" and compared her to one of his dumb students, it may have struck some as funny, but it might also have just seemed mean.

It would be easier to endure the absence of laughter if the campaigns weren't otherwise so silly. It's not just that the debates and interviews force candidates into contortions. It’s also that the candidates spend much of their time engaging in ridiculous hyperbole, offering straw man arguments, and pandering outrageously. If there's going to be clownish behavior, at least voters should get a few laughs out of it.