The Roman satirist Juvenal famously quipped "Difficile est saturam non scibere" -- it's difficult not to write satire. It was difficult nearly two millennia ago, and it still is today. What seems even more difficult now, however, is for the perennially offended in the media and academe to understand satire. Just ask Rush Limbaugh and Mike Adams.

Limbaugh and Adams have recently weathered ill-conceived attacks on their parodies, Limbaugh's song "Barack, the Magic Negro" and Adams' article supposedly advocating terrorism against gay bath houses in San Francisco. Opportunistic critics acted as if Limbaugh and Adams were seriously promoting racism and mass murder, when the truth was, both were turning to satire to denounce racism and mass murder.

One wonders, reading the overreactions to and deliberate misreadings of satire in today's climate, whether Jonathan Swift's publicist would have just resigned or tried to defend his client from reports that he advocated cooking kids in stews (as opposed, presumably, to harvesting their stem cells).

There is a simple but effective test of satire, one that hails back to Aristotle. "Humor is the only test of gravity, and gravity of humor," he said, "for a subject which will not bear raillery is suspicious, and a jest which will not bear serious examination is false wit."

Note that the great logician pinpointed a very compelling reason for using humor: it is the best test of ideas. Humor is a challenge to the very core of an idea -- its gravity, its seriousness. Laughter demands a response.

As Aristotle explains, an idea that cannot withstand mockery is suspicious. You shouldn't trust it. Those who cannot tolerate jokes cracked at their ideology's expense betray its weakness. Weak ideologies require something other than citizens' shared ideals and support to maintain their power; frequently they resort to the power of the gun. It's no coincidence that the Khmer Rouge and the Taliban banned laughter, or that citizens of Soviet Russia had to tell each other jokes behind their hands, hiding in bathrooms with the water running.

Also note that Aristotle provided a way to test the humor used to try an idea. It's not enough that there is a joke. The joke must be defensible; i.e., it must "bear serious examination." In other words, humor or satire should present a serious challenge to the idea, a challenge that can be investigated in its own right. If the humor fails to have a serious basis, it's "false wit." The satirist should therefore be able to defend his jest.

Back to Limbaugh and Adams. Controversy was slow in finding Limbaugh's months-old spoof, but it has been growing recently. On Monday, a TV morning show on KOVR CBS-13 in Sacramento, Calif., suggested that the song was racist and implied that it might even be responsible for putting Obama in mortal danger. On his show that day, Limbaugh proved the parody wasn't false wit.

In a line-by-line defense of the song, Limbaugh showed it spoofs the absurd problems Obama's candidacy poses to race-obsessed Democrats. Its lyrics make clear that its provocative title and some material hail from David Ehrenstein's March 19 Los Angeles Times article, "Obama, the 'Magic Negro.'" He showed how other portions were inspired by the Obama/Sharpton feud and the steady drip of media reports doubting whether Obama is "black enough." Continued...