Carmen Reinhart and Ken Rogoff came as close to celebrity status as an economist can ever come, with their book, This Time Is Different. They claimed that 800 years (!) of financial history proves that high government debt ratios lead to low economic growth. Governments all over the world took heed and downsized, adopting austerity that cost millions upon millions of workers their jobs.

But it was all a lie. Yes, a lie. They screwed up their data analysis. Like so many times before—think Larry Summers at Harvard, Chicago’s Gene Fama, or Charles Plosser at the University of Rochester—the economists reach results counter to intuition and the real world.

Their work doesn’t pass the smell test: if it smells like nonsense it probably is nonsense.

Yeva Nersisyan (my brilliant student and coauthor) and I critiqued their book soon after it came out; see here: To put our conclusions as simply as possible, we concluded that they didn’t know what they are talking about.

They argued that “high” government debt ratios—say, 90% of GDP—nearly invariably lead to slow growth and to financial crisis. Our debt hysterians took that and ran—using their book as justification for austerity.

We noticed that their data just did not add up. Leave to the side the silliness of simply aggregating across 8 centuries of experience, and adding up debt ratios of countries as disparate as the USA today or, say, Greece in 1932, let alone some feudal state operating on a gold standard a couple of hundred years ago. As I’ve remarked, any real historian would find the methodology ludicrous.

More importantly, they have no idea what sovereign debt is. They add together government debts issued by states on gold standards, fixed exchange rates and floating rates. They aggregated across governments that issue debt in their own currency and states that issue debt denominated in foreign currency. It is not even possible to determine from their book exactly what is government debt versus private debt.

When we couldn’t make sense of their results, Yeva wrote to them to get the data. After all, their book touted their contribution to good research by proclaiming they were accumulating all this data for the good of humanity. They ignored our request. I have heard from several other researchers that Rogoff and Reinhart also ignored their repeated requests for the data.

So, finally, someone was able to obtain the data. And as we suspected, it did not add up. Rogoff and Reinhart committed the cardinal sin of academics: while their purported results fit their theory, the data they supposedly used does not. Either they fudged or they erred. It really doesn’t matter. Their results were completely, utterly wrong. And their own data proves it.

You can read a summary of the expose here: The academic paper is here:

The paper confirms what we suspected: the Rogoff and Reinhart research is crap. They threw out all the high debt, good growth countries. If you put those back in, it simply is not true that high government debt leads to low growth.

Was it intentional? Who cares. Motive is not the issue. Crappy research is the problem. And this was one of the most cited papers in recent economic research. Here’s the abstract from the critical analysis of their work:

We replicate Reinhart and Rogoff and find that coding errors, selective exclusion of available data, and unconventional weighting of summary statistics lead to serious errors that inaccurately represent the relationship between public debt and GDP growth among 20 advanced economies in the post-war period. Our finding is that when properly calculated, the average real GDP growth rate for countries carrying a public-debt-to-GDP ratio of over 90 percent is actually 2.2 percent, not -0.1 percent as published in Reinhart and Rogoff. That is, contrary to RR, average GDP growth at public debt/GDP ratios over 90 percent is not dramatically different than when debt/GDP ratios are lower. We also show how the relationship between public debt and GDP growth varies significantly by time period and country. Overall, the evidence we review contradicts Reinhart and Rogoff’s claim to have identified an important stylized fact, that public debt loads greater than 90 percent of GDP consistently reduce GDP growth.

Whoops. Do Over?

Here’s the bigger problem highlighted by Yeva and Me: they do not know what they are talking about. Sovereign countries that issue their own floating currency cannot be forced into involuntary default no matter what the debt ratio. For that reason, even if their results had not been tainted by bad research, it would have been irrelevant to the situation of any country that issues its own floating currency, such as the USA, the UK, Japan, and so on. No matter what the debt ratio, a sovereign government that issues its own currency can choose to grow the economy.

That was the lesson that should have been learned. Here’s how we ended our critique:

When it comes to a sovereign government’s budget deficit and debt there are no magic numbers or ratios that are relevant for all countries and all times. There are no thresholds that once crossed will be unsustainable or lead to lower growth. The government’s budget balance in most advanced nations is highly endogenous and is merely the other side of the coin of the nongovernment sector’s balance. The public deficit is the result of the private sector’s willingness to net save and net import.

Modern monetary theory is often interpreted as claiming that there is no real limit to the government’s ability to spend or that the government should run up deficits. Of course there is a limit to the government’s ability to spend and of course it shouldn’t spend an infinite amount. Yet, the sovereign government is not constrained financially, which means that it can never face a solvency issue. Still, it is certainly constrained in real terms meaning it can face another kind of sustainability issue: how much of the nation’s resources ought to be mobilized by government? Given the level of resources that the nongovernment sector wants to mobilize, how large should the government’s deficit be to mobilize the rest?

More than five decades ago, Abba Lerner gave the answer to this question. If there are involuntarily unemployed (we would add underemployed) people it means the deficit is too low. The government should either cut taxes or increase spending. It is certainly debatable which one is a better policy, but that’s beyond the scope of this paper. When is the deficit too large? When it’s over 3%, 7%, 10%? Again, there is no magic number and anyone who comes up with a universal number simply misunderstands the modern monetary regime and macroeconomics. In opposition to magic, Lerner proposed “functional finance”—the notion that the federal government’s budgetary outcome is of no consequence by itself, but rather, what is important is the economic effects of government spending and taxing. When total spending in the economy, including government spending, is more than what the economy is able to produce when employed at full capacity, the government should either lower its spending or raise taxes. A failure to do so will lead to inflation. So inflation is the true limit to government spending not lack of financing. Government debt is merely the result of government deficit and hence the same applies to debt as well.

Lesson to learn: ignore the Ivory Tower economists who recommend austerity and warn of “unsustainable” budget deficits in the case of sovereign currency nations. They know not of what they speak.