The New Supply-Side Economics
Republicans Can’t Agree on a Budget – and It’s Hurting Their Agenda · The Fiscal Times

Traditionally, macroeconomic policy has been divided into two distinct types. The first type, stabilization policy, attempts to keep output and employment as close to their full employment levels as possible. The idea behind these policies is to minimize, or even eliminate, short-term boom-bust cycles around the natural rates of output and employment caused by fluctuations in aggregate demand.

The second type of policy, growth policy, works on the supply-side and attempts to keep the long-term natural rates of output and employment growing as fast as possible. Thus, if the long-term natural growth rate of output is, say, 2.5 percent, supply-side policy would try to increase this rate, while demand-side stabilization would try to keep us from deviating from it, whatever it might be.

Related: Economic Growth vs. Social Insurance—Why Can’t We Have Both?

Importantly, these policies were believed to be independent. Monetary and fiscal policy used to stabilize the economy could change how fast the economy returns to the natural rate after a positive or negative shock, but the policy would have no impact at all on the natural rate itself.

But what if this is wrong, as data from the Great Recession suggests? What if demand-side policies impact the natural rate after all? What does this mean for monetary and fiscal policy? It turns out to have important implications.

The belief that monetary policy cannot affect the natural rate of output led to the compartmentalization of stabilization and growth policy. Monetary policy was used to manage aggregate demand and stabilize the economy, while fiscal policy was mainly devoted to supply-side policies to enhance growth. Fiscal policy was used for stabilization at times, but the difficulty in getting fiscal policy through Congress quickly enough and of sufficient size to be useful for stabilization made it convenient to leave this job to monetary authorities where political gridlock is not a problem.

Related: Here’s an Economic Agenda for Hillary Clinton

A full telling of this story would also note the degree to which Republicans used the promise of growth from supply-side policies to implement legislation such as tax cuts for the wealthy that were more about ideological concerns and allegiance to political campaign donors than growth. But I don’t think it’s a stretch to say that fiscal policy was used to try to boost investment and saving, eliminate distortions that inhibit growth, and so on to a much greater degree than it was used as a stabilization tool.

The Great Recession brought about two changes in the view of how monetary and fiscal policy should be conducted. First, as I and others have noted many times, it is now clear that in a deep recession monetary policy alone is not enough to stabilize the economy, fiscal policy is also needed. During the period of mild fluctuations in output and employment from 1982 through 2007 known as the Great Moderation monetary policy could do the job by itself, and to a large extent we forgot about fiscal policy as a stabilization tool.