Thomas Friedman, author of 'The World Is Flat'

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In response to the dangers posed by al-Qaida, Thomas has tried to remain fearless. Instead, he's been "going golfing. My motto is leave the cave-dwelling to bin Laden," he says.

Thomas says terrorists have effectively turned the best parts of our society—openness and trust—into what appears to be a sense of vulnerability. "What these people are doing is they're taking instruments from our daily life—the backpack, the car, the shoe, the cell phone—and they're turning them into weapons," he says. "In doing that, they're forcing us to take trust out of our open society. That's why it is so dangerous."