## Tuesday, January 10, 2012

### Simon Wren-Lewis: Mistakes and Ideology in Macroeconomics

Via Chris Dillow, this is Simon Wren-Lewis of Oxford University:

Mistakes and Ideology in Macroeconomics, by Simon Wren-Lewis: Imagine a Nobel Prize winner in physics, who in public debate makes elementary errors that would embarrass a good undergraduate. Now imagine other academic colleagues, from one of the best faculties in the world, making the same errors. It could not happen. However that is exactly what has happened in macro over the last few years.

Where is my evidence for such an outlandish claim? Well here is Nobel prize winner Robert Lucas

But, if we do build the bridge by taking tax money away from somebody else, and using that to pay the bridge builder -- the guys who work on the bridge -- then it's just a wash.  It has no first-starter effect.  There's no reason to expect any stimulation.  And, in some sense, there's nothing to apply a multiplier to.  (Laughs.)  You apply a multiplier to the bridge builders, then you've got to apply the same multiplier with a minus sign to the people you taxed to build the bridge.

And here  is John Cochrane, also a professor at Chicago, and someone who has made important academic contributions to macroeconomic thinking.

Before we spend a trillion dollars or so, it’s important to understand how it’s supposed to work.  Spending supported by taxes pretty obviously won’t work:  If the government taxes A by \$1 and gives the money to B, B can spend \$1 more. But A spends \$1 less and we are not collectively any better off.

Both make the same simple error. If you spend X at time t to build a bridge, aggregate demand increases by X at time t. If you raise taxes by X at time t, consumers will smooth this effect over time, so their spending at time t will fall by much less than X. Put the two together and aggregate demand rises.

But surely very clever people cannot make simple errors of this kind? Perhaps there is some way to re-interpret such statements so that they make sense. ,,. Brad deLong tries very hard along these lines (see here for example), but just throws up inconsistencies.

I prefer to just note that if any undergraduate or graduate student in the UK wrote this in an exam, they would lose marks. The more interesting question for me is why the errors were made. ...

I want to suggest two answers. The first is familiarity with models. I cannot imagine anyone who teaches New Keynesian economics, or who talked to people who teach New Keynesian economics, making this mistake. This is because, in these models, we do have to worry about aggregate demand. We focus on consumption smoothing, and Ricardian Equivalence... I often tell my first year undergraduate students that if they write anything like ‘Ricardian Equivalence says fiscal stimulus will never work’, they are in danger of failing. ...

Lack of familiarity with New Keynesian economics may be partly explained by the history of macroeconomic thought that I briefly noted in an earlier post. As New Keynesian theory is an ‘add-on’ to the basic Ramsey/RBC model, it is possible to teach macro without getting round to teaching New Keynesian theory. However, what many people find difficult to understand is how monetary policy (or at least monetary policy as seen by pretty much every central bank) could be regarded as an optional add-on in macroeconomics.

The second difference between physics and macro that could lead to more mistakes in the latter is ideology. When you are arguing out of ideological conviction, there is a danger that rhetoric will trump rigour. In the next paragraph Cochrane writes

These ideas changed because Keynesian economics was a failure in practice, and not just in theory. Keynes left Britain 30 years of miserable growth. Richard Nixon said, “We are all Keynesians now,” just as Keynesian policy led to the inflation and economic dislocation of the 1970s--unexpected by Keynesians but dramatically foretold by Milton Friedman’s 1968 AEA address. Keynes disdained investment, where we now all realize that saving and investment are vital to long-run growth. Keynes did not think at all about the incentives effects of taxes. He favored planning, and wrote before Hayek reminded us how modern economies cannot function without price signals.   Fiscal stimulus advocates are hanging on to a last little timber from a sunken boat of ideas, ideas that everyone including they abandoned, and from hard experience. ...

Let’s not worry about where the idea that Keynes disdained investment comes from, or any of the other questionable statements here. This is just polemic: Keynes=fiscal expansion=planning=macroeconomic failure.  It is guilt by association. What on earth does fiscal expansion have to do with planning? Well, they are both undertaken by the state.

I have argued elsewhere that the problem too many macroeconomists have with fiscal stimulus lies not in opposing schools of thought, or the validity of particular theories, or the size of particular parameters, but instead with the fact that it represents intervention by the state designed to improve the working of the market economy. They have an ideological problem with countercyclical fiscal policy. But the central bank is part of the state, and it intervenes to improve how the economy works, so this ideological view would also mean that you played down the role of monetary policy in macroeconomics. So ideology may also help explain a lack of familiarity with the models central banks use to think about monetary policy. In short, an ideological view that distorts economic thinking can lead to mistakes.

Posted by on Tuesday, January 10, 2012 at 10:03 AM in Economics, Macroeconomics, Methodology | Permalink  Comments (59)