Confronted by the sold out auditorium at Symphony Space this Wednesday, Superfreakonomics co-author and prize winning economist Steven Levitt had this to say: “You know, this is the first time that this has ever happened, that people had to pay to see us and that people actually showed up.”

Levitt wasn’t kidding. Before his and co-author Stephen Dubner’s first book Freakonomics won renown, a concert hall in Dallas canceled a talk when only eight tickets were purchased.

Of course, that has all changed. Freakonomics spent 111 weeks on The New York Times bestseller list and spawned a whole subset of similarly titled books (Soccernomics, Wikinomics, and so on).

The audience Wednesday night reflected Freakonomics‘ success. A wide spectrum of attendees – from kicks-sporting teens to elderly couples and coworkers – packed the hall for the authors’ only New York appearance. They listened as Dubner and Levitt recounted the story of their meeting and then joined the conversation in a question and answer session.

Though Dubner and Levitt had some charming anecdotes (Dubner remembers the first call he received after the book came out – a thank-you from Levitt’s mother, happy that he had “treated my son fair”), the most interesting parts of the evening occurred during the Q and A.

For over an hour, audience members queried the authors about controversial chapters in both the new book and its predecessor. One woman said she had recently read about a study that disproved Freakonomics‘ assertion that the legalization of abortion is directly related to a reduction in crime. Another noted the controversy surrounding a chapter on global warming in Superfreakonomics, and asked Levitt and Dubner to respond to allegations that the chapter misrepresents climatologists’ views.

In their responses to these questions, both authors displayed remarkable cool. At no point did they turn emotional or disgruntled, despite the fact that the criticisms were, in Dubner’s words, “serious.”

It is especially telling how Levitt replied to the question on climate change. Their goal, he said, was not to undermine or criticize the efforts of environmentalism to change consumers’ behavior, but to rationally examine other solutions that should be on the table. Carbon mitigation strategies, he pointed out, are expensive, difficult and will not show results for 50 to 100 years. On the other hand, acting directly to cool the planet using geo-engineering would have quick results and cost less. Levitt’s measured response displayed a clarity of thinking worthy of a world class economist. He did note, however, that “Geo-engineering is a solution to global warming in much the way that methadone is a solution to heroin.”

Dubner added that the climatologist in question actually ran models of his own design to test the geo-engineering alternatives highlighted in Superfreakonomics and found that they would work. “He read over the book,” Dubner said, dispelling the notion that Superfreakonomics distorts his views.

Perhaps the most interesting question posed – “Based on your research into the economics of prostitution, should prostitution be legalized?” – went unanswered. Levitt and Dubner only had time to highlight the chapter in their book before the event host came onstage to conclude the discussion.

Despite coming to a close too soon, the evening was a balanced composition of laughter and instruction. The quick banter between the two authors provided a rare glimpse into such a successful literary relationship. Though neither Dubner nor Levitt expected their zany book to succeed, the stream of audience members queing in the lobby for autographs after the event shows how far they have come.