A pair of authors takes a look at the what, why, and how of American comedy in a new book and companion documentary. IT WAS EARLY 2004, and the heated November presidential election was inching closer by the day. Michael Kantor and Laurence Maslon had just wrapped the PBS documentary series about the history of New York theater called Broadway: The American Musical, and they realized that America was tense. “There was something about the moment in time and the country being polarized that made me think, ‘We could use a good joke right now,’ ” Kantor says. Better yet, he thought, a century of good jokes.So Kantor and Maslon set about chronicling the history of humor in the United States for a new book, Make ’Em Laugh: The Funny Business of America (Twelve Books, $45), and its accompanying six-part documentary series of the same name, which will air on PBS in January. The duo gave us the scoop on their entertaining new project.A century of American comedy is a pretty big topic to tackle. How did you handle it?KANTOR: What we realized is that comedy is all about surprise. If we told this story chronologically in the documentary, we would lose a lot of the surprise.MASLON: Or the first hour would have been black-and-white and silent, and good luck getting people to tune in to episode two. So one afternoon, we wrote out major figures [of comedy] on an index card -- and a couple of favorites who hadn’t achieved mass-market ubiquity. We found out very quickly you could put them into six different categories. That made us realize Larry David and W.C. Fields aren’t so far off, and that what Jon Stewart is trying to do is in the same vein of what Will Rogers was trying to do.You interviewed many big names in comedy for the project. What was that like?KANTOR: Comedians can be very serious when they’re thinking about their career or talking about other people’s work. There’s definitely a dichotomy between somebody onstage, who might use vulgar language and say outrageous things, and the kind of shy and considerate person you meet in a living room.MASLON: I think one of the things that was fascinating to me … was how generous these comedians were. I was just amazed at how comedians really felt they were standing on the shoulders of giants. Bob Newhart was in awe of Richard Pryor. Joan Rivers was in awe of Lucille Ball.KANTOR: Steve Martin was in awe of Jerry Lewis.Overall, how would you characterize comedians?KANTOR:Chris Rock said that all comedians are nerds and geeks, and if you can take your shirt off on camera …MASLON: Without people laughing …KANTOR: Then you’re not a comedian.