Barton's and Zinn's works have also made a discernible impression on secondary education. Barton served as an expert consultant for the Texas State Board of Education's recent revamp of its influential state social studies curriculum, while A People's History (which first appeared more than three decades ago) is aggressively marketed by an education project that bears Zinn's name and has been taught in countless middle school and high school classes.

It's not just that Barton and Zinn have large constituencies. They also inspire a degree of passion that verges on the pugnacious. In early 2011, Mike Huckabee quipped that the country's schoolchildren should be forced "at gunpoint ... to listen to every David Barton message." (Elaborating on his pedagogical vision, Huckabee suggested that students be exposed to Barton's teaching through a "simultaneous telecast.") Zinn received his own bellicose endorsement from Matt Damon's character in the 1997 film Good Will Hunting. "If you wanna read a real history book," Damon instructed his therapist, "read Howard Zinn's A People's History of the United States. That book'll [expletive] knock you on your [expletive]."

What exactly is it about Barton's and Zinn's versions of history that inspire such uncompromising, take-no-prisoners fervor? And how do they manage to wield so much influence, given the widespread skepticism about their accuracy?

Partisanship is the first answer that comes to mind. Barton and Zinn have served as eloquent and vocal supporters of right- and left-wing causes respectively, and both have reworked the past for transparently political purposes. Each has offered conclusions that resonate with his audiences' beliefs. Whatever the validity of their claims, in other words, many readers apparently think they should be true. (It's also likely that partisanship accounts for some proportion of votes against Barton and Zinn's credibility.)

But that's only part of the explanation. There's a more insidious mechanism that helps explain both the passionate support these authors inspire and the well-founded suspicion that they are fudging the record. In short, Barton and Zinn have each crafted a sort of Da Vinci Code history. Nearly everyone knows the basic plotline of that bestselling Dan Brown novel, which leads readers via a highly dubious series of clues to the previously undisclosed origin of Christianity while unraveling the malicious web of deception that concealed it for centuries.

Adapting this gripping storytelling approach, Barton and Zinn offer audiences the illusion that they have been hoodwinked by undisclosed authorities -- Ivy League academics, textbook authors, the New York Times, eighth-grade social studies teachers, parents. They give readers the intellectual self-assurance that accompanies expertise without the slog of unglamorous study required to attain it.