As you’ll know if you’ve been near any economics-oriented blogs, secular stagnation is the hot topic i.e. that advanced economies are prone to needing negative real interest rates to achieve full employment and in the inability to achieve that at low inflation, bubbles might be helpful. One surprising thing about the debate is that given the Cambridge Mass. lineage of those involved in it, the concept of “dynamic inefficiency” has not been raised in tandem.
This was something that emerged in the modeling of overlapping generations economies by Paul Samuelson and Peter Diamond, and referred in particular to the possibility of the economy where “the” interest rate was less than the growth rate and thus in a sense the economy’s saving vehicles were less efficient at transferring wealth to the future than its growth process. The intuition was that such an economy had accumulated too much capital and driven down its return, while the saving needed to maintain the capital at that level (due to depreciation) was squeezing current consumption.
Such an economy has the possibility that weird stuff — like bubbles, paper money, and unfunded social security — can make everyone better off. Also, the government can pile up debt, and seemingly dubious investments like land are good for everyone.
Indeed, such an economy is essentially a long-term version of the liquidity trap, where the standard instincts about good and bad policy don’t work very well. It’s also mathematically interesting, which perhaps is why it’s such a staple of graduate level textbooks.
So why is no one talking about it, at least not explicitly? Is it that the intuition of overinvestment doesn’t sound right for economies seemingly short of infrastructure, like the USA and Germany? Or correspondingly that the high saving part doesn’t sound right, at least for the USA? Perhaps it’s the fact that various means of increasing current consumption at the non-expense of future generations — like selfish tax cuts! — are helpful.
In any event, much of the secular stagnation discussion has been conducted in terms of the static relationship between saving and investment. The dynamic inefficiency tradition has the merit of looking at the cumulative impact over time of all that excess saving. In the secular stagnation world, where is all that capital going?