For more than two centuries, Americans have gotten away with not knowing much about the world around them. But times have changed—and they’ve changed in ways that make civic ignorance a big problem going forward. While isolationism is fine in an isolated society, we can no longer afford to mind our own business. What happens in China and India (or at a Japanese nuclear plant) affects the autoworker in Detroit; what happens in the statehouse and the White House affects the competition in China and India. Before the Internet, brawn was enough; now the information economy demands brains instead. And where we once relied on political institutions (like organized labor) to school the middle classes and give them leverage, we now have nothing. “The issue isn’t that people in the past knew a lot more and know less now,” says Hacker. “It’s that their ignorance was counterbalanced by denser political organizations.” The result is a society in which wired activists at either end of the spectrum dominate the debate—and lead politicians astray at precisely the wrong moment.

With a trace of humor and no small amount of pride, Kelly Gneiting, 40, calls himself the Fat Man. He weighs 405 pounds and is not embarrassed by an ounce of it. He stands out. He is one of a very few white people on the reservation. He is 6 feet tall with a 60-inch waist. That makes him 5 feet around the middle. His fleshy body is devoid of angles.

Even so, he is an athlete, and he is hardly shy about saying how good he is. “I honestly think I’m one of the best athletes in the world,” he says. Bold overstatement, maybe, but this man who weighs nearly a quarter ton can do the splits, then bend at the waist and shoulders until his forehead touches the ground. He can reel off four consecutive sets of 25 pushups.

The Fat Man is a three-time national champion sumo wrestler.

But his evidence can also be used to tell a related story. It could be that the nature of technological change isn’t causing the slowdown but a shift in values. It could be that in an industrial economy people develop a materialist mind-set and believe that improving their income is the same thing as improving their quality of life. But in an affluent information-driven world, people embrace the postmaterialist mind-set. They realize they can improve their quality of life without actually producing more wealth.