From Chait, the best synopsis I've read yet:
The federal government shutdown, while important, is a dry run for the potentially cataclysmic debt-ceiling standoff. What does it portend? Evidence can be found for both alarm and complacency, but the preponderance of proof seems to lie on the side of freaking out.
In one stumbling way, or another, we will of course get through this. But the magnitude of the stumbles is what worries.
Sure, we stumbled our way through and out of the sectional crisis of the 1850s, too, but its aftershocks were both devastatingly immediate and chronically haunting; in fact, they laid the geopolitical foundation for today's madness.
So we're left asking, How big of a stumble can the nation bear, without crippling its fundamental character?