A Model of Secular Stagnation

Gauti Eggertson and Neil Mehotra have an interesting new paper:

A Model of Secular Stagnation, by Gauti Eggertsson and Neil Mehrotra: 1 Introduction During the closing phase of the Great Depression in 1938, the President of the American Economic Association, Alvin Hansen, delivered a disturbing message in his Presidential Address to the Association (see Hansen ( 1939 )). He suggested that the Great Depression might just be the start of a new era of ongoing unemployment and economic stagnation without any natural force towards full employment. This idea was termed the ”secular stagnation” hypothesis. One of the main driving forces of secular stagnation, according to Hansen, was a decline in the population birth rate and an oversupply of savings that was suppressing aggregate demand. Soon after Hansen’s address, the Second World War led to a massive increase in government spending effectively end- ing any concern of insufficient demand. Moreover, the baby boom following WWII drastically changed the population dynamics in the US, thus effectively erasing the problem of excess sav- ings of an aging population that was of principal importance in his secular stagnation hypothesis.

Recently Hansen’s secular stagnation hypothesis has gained increased attention. One obvious motivation is the Japanese malaise that has by now lasted two decades and has many of the same symptoms as the U.S. Great Depression - namely dwindling population growth, a nominal interest rate at zero, and subpar GDP growth. Another reason for renewed interest is that even if the financial panic of 2008 was contained, growth remains weak in the United States and unemployment high. Most prominently, Lawrence Summers raised the prospect that the crisis of 2008 may have ushered in the beginning of secular stagnation in the United States in much the same way as suggested by Alvin Hansen in 1938. Summers suggests that this episode of low demand may even have started well before 2008 but was masked by the housing bubble before the onset of the crisis of 2008. In Summers’ words, we may have found ourselves in a situation in which the natural rate of interest - the short-term real interest rate consistent with full employment - is permanently negative (see Summers ( 2013 )). And this, according to Summers, has profound implications for the conduct of monetary, fiscal and financial stability policy today.

Despite the prominence of Summers’ discussion of the secular stagnation hypothesis and a flurry of commentary that followed it (see e.g. Krugman ( 2013 ), Taylor ( 2014 ), Delong ( 2014 ) for a few examples), there has not, to the best of our knowledge, been any attempt to formally model this idea, i.e., to write down an explicit model in which unemployment is high for an indefinite amount of time due to a permanent drop in the natural rate of interest. The goal of this paper is to fill this gap. ...[read more]...

In the abstract, they note the policy prescriptions for secular stagnation:

In contrast to earlier work on deleveraging, our model does not feature a strong self-correcting force back to full employment in the long-run, absent policy actions. Successful policy actions include, among others, a permanent increase in inflation and a permanent increase in government spending. We also establish conditions under which an income redistribution can increase demand. Policies such as committing to keep nominal interest rates low or temporary government spending, however, are less powerful than in models with temporary slumps. Our model sheds light on the long persistence of the Japanese crisis, the Great Depression, and the slow recovery out of the Great Recession.