baseline scenario

The Arithmetic of Fantasy Fiscal Policy by Krugman

Sometimes — usually, though not always, in a belligerent tone — people ask me, well, how big do you think the stimulus should have been? How much debt should we have run up? Regardless of the tone, that is actually a question worth answering. With the benefit of hindsight, we do know roughly how depressed the economy has been; we have reasonably good estimates of the effects of government spending; so we can put together an estimate of what would have happened if we had, in fact, pursued a policy of government spending sufficient to keep output at potential. 

Start with the CBO estimates of potential GDP, which can be subtracted from actual GDP to estimate the output gap. Start the clock at the beginning of 2009, and the output gap — measured quarterly, but at an annual rate — looks like this: 

 

The output gap. 

If you add it up, the cumulative output gap since start-2009 comes to $2.29 trillion — that is, $2.29 trillion worth of goods and services we could and should have produced, but didn’t. 

How much government spending would have been required to close that gap? The evidence is now overwhelming that when you’re at the zero lower bound the multiplier is greater than one; see,e.g., Blanchard and Leigh. Suppose we take a multiplier of 1.3, which is fairly conservative. Then it would have taken $1.76 trillion in spending over the past 4 1/2 years to close the output gap. Yes, I know, it would have been politically impossible — but we’re just doing the economics here. 

So is that an extra $1.76 trillion in debt? No — the economy would have been stronger, leading both to higher revenue and to lower spending on means-tested programs. A fairly conservative estimate is that each dollar of extra GDP would have saved 1/3 of a dollar in the form of higher revenue and lower spending, which means 2.29/3 = $0.76 trillion. 

So the net extra debt we would have run up with my fantasy stimulus turns out to be a round $1 trillion. OMG: ONE TRILLION DOLLARS! 

But how bad is that? It’s about 6 percent of GDP. And remember, also, that GDP would have been higher — it would have been at potential, not well below. So at this point, instead of where we are — with federal debt at 72 percent of GDP — we would have had federal debt at 76 percent of GDP. Does anyone seriously claim that this difference would have caused a fiscal crisis? 

And in return for those 4 points on the debt ratio, millions of American families would have been spared the hardship and humiliation of mass unemployment, lost houses and savings, and more. We can further argue that by avoiding the corrosive effects of long-term unemployment, we would surely have avoided substantial damage to America’s longer-run economic prospects, which in turn means that future revenue would be higher — and my fantasy fiscal program would probably have improved, not worsened, our fundamental fiscal position. 

Again, I understand that none of this was going to happen. But you should understand that this reflects bad judgment by bad politicians and bad economists, not the logic of the case.