America’s social harmony has depended at least to some degree on economic growth. It is easier to get along when everyone, more or less, is getting ahead. But when the pie is shrinking, social groups are more likely to turn on each other. America has always been a remarkably classless society—obsessed by status and money, perhaps, but fluid enough so there was never an identifiable social class that was able to keep the rest out. But as the perception grows that the rich are intent on getting richer and the rest be damned, the folks outside the gated community are growing restless…

Little lies can add up to one Big Lie. Obama is a socialist! Health reform means death panels! They’re going to take away your guns! I don’t mean to be apocalyptic. I don’t think that Big Brother beckons. But the old and weary (and increasingly cowed) mainstream media, of which I have been a charter member for more than 30 years, may not be as successful as it used to be at exposing the sort of distortions that can fuel mindless rage. Whether those distortions come from the far right or far left, the consequences could be disastrous: a protectionist who sets out to shield workers from foreign competition and wrecks the free-trade regimen that has made America prosper; a law-and-order vigilante who comes to office after a terrorist attack with a program to suspend cherished individual liberties to keep America “safe”; a soak-the-rich populist who kills economic growth in the name of helping the little guy.