Must-read: Paul Krugman (1999): “Thinking About the Liquidity Trap”

Must-Read: One thing that I find very interesting about Paul Krugman’s analysis of the liquidity trap and fiscal policy back in 1999 is… how very closely it tracks Ken Rogoff’s analysis of the liquidity trap and fiscal policy today:

Paul Krugman (1999): Thinking About the Liquidity Trap: “Fiscal policy: “The story… [of] self-fulfilling pessimism is… a multiple equilibrium story…

…with the liquidity trap corresponding to the low-level equilibrium…. Over some range spending rises more than one-for-one with income. (Why should the relationship flatten out at high and low levels? At high levels resource constraints begin to bind; at low levels the obvious point is that gross investment hits its own zero constraint. There is a largely forgotten literature on this sort of issue, including Hicks (194?), Goodwin (194?), and Tobin (1947))….

Thinking about the liquidity trap

Multiple equilibria… allow for permanent (or anyway long-lived) effects from temporary policies. There may be excess desired savings even at a zero real interest rate given the pessimism that now prevails… but if some policy could push the economy to a high level of output for long enough to change those expectations, the policy would not have to be maintained…. Balance-sheet problems… may involve an element of self-fulfilling slump: a firm that looks insolvent with an output gap of 10 percent might be reasonably healthy at full employment….

‘Pump-priming’ fiscal policy is the conventional answer to a liquidity trap…. In either the IS-LM model or a more sophisticated intertemporal model fiscal expansion will indeed offer short-run relief…. So why not consider the problem solved? The answer hinges on the government’s own budget constraint….

Ricardian equivalence… is not the crucial issue…. Real purchases… will still create employment…. (In a fully Ricardian setup the multiplier on government consumption will be exactly 1)….

The problem instead is that deficit spending does lead to a large government debt, which will if large enough start to raise questions about solvency. One might ask why government debt matters if the interest rate is zero…. But the liquidity trap, at least in the version I take seriously, is not… permanent…. [When] the natural rate of interest… turn[s] positive… the inherited debt will indeed be a problem….

Fiscal policy [is] a temporary expedient that cannot serve as a solution [unless]….

First, if the liquidity trap is short-lived… fiscal policy can serve as a bridge… after [which]… monetary policy will again be able to shoulder the load… a severe but probably short-lived financial crisis in trading partners… breathing space during which firms get their balance sheets in order….

[Second, if] it will jolt the economy into a higher equilibrium…. If this is the underlying model… one must realize that the criterion for success is quite strong…. Fiscal expansion… must lead to… increases in private demand so large that the economy begins a self-sustaining process of recovery….

None of this should be read as a reason to abandon fiscal stimulus…. But fiscal stimulus… [is] a way of buying time… [absent] assumptions that are at the very least rather speculative…

December 17, 2015


Brad DeLong
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