The debt limit is a routine vote that Congress must periodically make to authorize payment on debts the government has incurred. It has no impact on the budget, but the failure to lift the debt ceiling means the U.S. government would go into default, a potentially disastrous event. Republicans used the threat of default to extract fiscal-policy concessions from the Obama administration in 2011, and they've attempted to repeat this hostage-taking periodically since. Some Republicans attempt to use as leverage the very credible belief that they are loopy enough to potentially set off a worldwide economic meltdown. South Carolina Republican Mick Mulvaney tells the New York Times, “I’ll play chicken with you every time. You think I am crazy, and I know you are not.” (I prefer to be governed by political parties whose leading members can answer questions about their sanity unambiguously, but your mileage may vary.)
Ben Carson, on the other hand, is in an even stronger position. He not only can exploit the perception that he is crazy, but he could, if elected president, take advantage of the fact that he literally does not know what the debt limit is. Kai Ryssdal has a harrowing interview with him, in which his lack of familiarity with the debt limit comes through clearly:
Ryssdal: All right, so let's talk about debt then and the budget. As you know, Treasury Secretary Lew has come out in the last couple of days and said, "We're gonna run out of money, we're gonna run out of borrowing authority, on the fifth of November." Should the Congress then and the president not raise the debt limit? Should we default on our debt?
Carson: Let me put it this way: if I were the president, I would not sign an increased budget. Absolutely would not do it. They would have to find a place to cut.
Ryssdal: To be clear, it's increasing the debt limit, not the budget, but I want to make sure I understand you. You'd let the United States default rather than raise the debt limit.
Carson: No, I would provide the kind of leadership that says, "Get on the stick guys, and stop messing around, and cut where you need to cut, because we're not raising any spending limits, period."
Ryssdal: I'm gonna try one more time, sir. This is debt that's already obligated. Would you not favor increasing the debt limit to pay the debts already incurred?
Carson: What I'm saying is what we have to do is restructure the way that we create debt. I mean if we continue along this, where does it stop? It never stops. You're always gonna ask the same question every year. And we're just gonna keep going down that pathway. That's one of the things I think that the people are tired of.
You think Carson is bluffing? He is not bluffing. This is a man who thinks “highfalutin scientists” concocted the theories of evolution and the origins of the universe for Satanic reasons. A reminder: Carson is the second-most-popular choice among Republicans to be their party’s nominee for president of the United States, behind the comparatively sober and well-informed Donald Trump.