A full house of 700 people crammed into the Grand Maple Ballroom of the Davis Center on Wednesday afternoon to watch Bill McKibben, award-winning writer, environmentalist, and Middlebury College scholar-in-residence, take on Russell Roberts, a prominent economist at George Mason University and Stanford University's Hoover Institute.

The occasion was an event titled "Buy Local or Buy Global: A Debate," the inaugural match-up in a new debate series called the Janus Forum featuring thinkers with opposing views on important social and economic issues.

Listen to a recording of the debate on UVM's iTunes U page. (Clicking on the link will launch iTunes on your computer, or prompt you to download the program.)

The event delivered Crossfire-like heat, on occasion, but a good amount of light, as both speakers enumerated in detail the environmental and economics analyses for which they're known, McKibben in support of the buy-local movement, Roberts in opposition.

The rules of the debate, spelled out by moderator Emerson Lynn, editor and publisher of the St. Albans Messenger, called for each speaker to deliver a 20 minute opening argument, followed by a 10 minute rebuttal of the other's position, concluding with questions from the audience.

McKibben opened the session with a high-speed recitation of 14 points, each one bristling with research citations, supporting the notion that buying food and energy locally would result in both a more environmentally durable economy and more cohesive communities. He challenged Roberts to answer his points — ranging from the fact that fertilizer-intensive agribusiness is eroding soil, an historic hallmark of civilizations that collapse, to the idea that Wal-Marts and other box stores deplete community well being and actually shorten lifespan — any one of which would win him the debate, he argued, if not factually disproven.

Roberts allowed his analysis to range beyond food and energy, which were set in advance as the twin focal points of the debate, McKibben reminded audience members several times, to more comprehensively indict the buy-local movement. Humans always want "more and better," Roberts said. While it's important to temper that basic human urge, he said, human striving has resulted in a bounty of innovation unimaginable100 years ago that has made life better. Eschewing global trade in favor of buy-local style self sufficiency, he said, is the road to poverty.

The mismatch in opening statements — McKibben presenting a detailed critique, Roberts offering a macro-economic analysis — led to one of the more pointed exchanges of the afternoon.

McKibben, describing Robert's remarks as a soliloquy, chided him for not answering his points (helpfully going through all 14 of them again). Roberts, he said, was presenting "assertion without evidence" and warned of the dangers of that rhetorical style by citing a radio interview Roberts did a year ago, where he downplayed the impact of sub-prime mortgage lending.

Admitting that he and many others erred on the mortgage issue but clearly piqued, Roberts responded that it was ironic for a graduate of the University of Chicago — where Roberts earned a Ph.D. in economics, studying under the legendary proponent of data driven analysis, Milton Friedman — to be criticized for lack of evidentiary rigor by "a guy in a sweater."

In his own inspired turn of phrase, McKibben took issue with Robert's characterization of life in an overly romanticized agricultural past as, in Thomas Hobbes phrase, "nasty, brutish and short," by asking audience members if they had ever been to Burlington's Intervale.

"Does it look like a Hobbsian hellhole to you?" he asked.

The two went back and forth over the reliability of the research studies McKibben cited. One study, by the United Nation Food and Agriculture Organization, demonstrating that world poverty was on the rise, provoked another salty exchange.

Roberts flatly disputed the study, saying poverty would be difficult to define and measure in a nation, let alone over the entire global population.

"Then we live in an existential universe where data doesn't matter," McKibben said.

"Numbers are important, Bill," Roberts shot back.

While there was no formal adjudication to determine the debate's winner, it was clear where the audience stood. During the Q&A period, nearly all of the dozen or so questioners asked pointed questions of Roberts and seemed supportive of McKibben's ideas.

That was likely due, however, not to debating prowess — although McKibben exhibited it in abundance — but to the audience's political predisposition, which Roberts, forewarned as he must have been about Vermont, might have miscalculated.

At one point he asked the students in the audience to stand, then asked those who did not intend to be farmers to sit. Quite a few remained defiantly on their feet, as the audience hooted and applauded.

"When I survey high school and colleges students" and ask this question, Roberts said, most sit down, "but maybe it's a different crowd here."

The Janus Project at UVM was established to produce a series of debates on important social and economic issues facing society and to stimulate reasoned discussion of those issues. The debates will stress the contrast and relative effectiveness of solutions that rely on freedom of individual choice as opposed to governmental or regulatory-based approaches to problems. The goal of the series is to improve our understanding of these alternatives through a direct confrontation of competing ideas. The topic of the next Janus Forum debate, scheduled for the spring of 2009, is health care.