The whole tone of current discussion about deficits is one of urgency: deficits must be brought down now now now or crisis looms. Where is this coming from? Not from the arithmetic.
The way the story is often told, deficits mean higher debt, which means higher interest payments, which can mean a spiral into bankruptcy. And qualitatively that’s not wrong. If you put numbers to it, however, for countries that are not facing huge risk premia, the spiral is very, very slow. (My italics)
---Balance of post here. He says the post is "Wonkish" but it's very easy to follow.