A country that spends and spends and spends and does not tax sufficiently will eventually run into debt-generated trouble. Its nominal interest rates will rise as bondholders fear inflation. Its business leaders will hunker down and try to move their wealth out of the corporations they run for fear of high future taxes on business. Real interest rates will rise because of policy uncertainty, and make many investments that are truly socially productive unprofitable. When inflation takes hold, the web of the division of labor will shrink from a global web he'd together by thin monetary ties to a very small web solidified by social bonds of trust and obligation--and a small division of labor means low productivity. All of this is bound to happen. Eventually. If a government spends and spends and spends but does not tax sufficiently.
But can this happen as long as interest rates remain low? As long as stock prices remain buoyant? As long as inflation remains subdued. My faction of economists--including Larry Summers, Laura Tyson, Paul Krugman, and many many others--believe that it will not. As long as stock prices are buoyant, business leaders are not scared of future taxes or of policy uncertainty. As long as interest rates remain low, there is no downward pressure on public investment. And as long as inflation remains low, the extra debt that governments are issuing is highly-prized as a store of value, helps savers sleep more easily at night, and provides a boost to the economy as it assists deleveraging and raises the velocity of spending.
Economists, you see, don't watch just quantities--the amount of debt a government has issued--but prices. And the prices of government debt are the rate of inflation, the nominal interest rate, and the level of the stock market as people trade bonds for commodities, bonds for cash, and bonds for stocks. And all three of these prices are flashing green: saying that markets would prefer and it would be better for the economy if government debt were growing at a faster pace than under current forecasts.
When Carmen Reinhart and Kenneth Rogoff wrote their "Growth in a Time of Debt," they asked the question: "Outsized deficits and epic bank bailouts may be useful in fighting a downturn, but what is the long run macroeconomic impact or higher levels of government debt, especially against the backdrop of graying populations and rising social insurance costs?" They concluded that over the past 200 years: