In the following video, he explains that the economy is not like a family. If the public and private sectors both try to pay down debt, it will just cause a depression in which no one effectively pays down debt. We’ve seen this in southern Europe where intense austerity has so depressed the economy that debt-to-GDP ratios have actually gone up in some countries. But his main point is that austerity is just another way to make the poor pay for the mistakes of the rich. As he notes: first the poor paid for the bank bailouts and then they paid again by the austerity cuts in programs.
Check out the video. It’s only five minutes, but you might want to watch it a few times: