On criticising the existence of mainstream economics

I’m very grateful to Unlearning Economics (UE) for writing in a clear and forceful way a defence of the idea that attacking mainstream economics is a progressive endeavor. Not criticising mainstream economics - I’ve done plenty of that - but attacking its existence. The post gets to the heart of why I think such attacks are far from progressive.

It is very similar to debates over whether economics teaching should devote considerable time to the history of economic thought and non-mainstream ideas, and whether economists have much too much power and influence. More critical thinking, real world context and history - yes. This is what the CORE project is all about. But devoting a lot of time to exposing students to contrasting economic frameworks (feminist, Austrian, post-Keynesian) to give them a range of ways to think about the economy, as suggested here, means cutting time spent on learning the essential tools that any economist needs. As Diane Coyle and I argue, economics is a vocational subject, not a liberal arts subject.

Let me start at the end of the UE piece.

“The case against austerity does not depend on whether it is ‘good economics’, but on its human impact. Nor does the case for combating climate change depend on the present discounted value of future costs to GDP. Reclaiming political debate from the grip of economics will make the human side of politics more central, and so can only serve a progressive purpose.”

Austerity did not arise because people forgot about its human impact. It arose because politicians, with help from City economists, started scare mongering about the deficit. We had ‘maxed out the nation’s credit card’ and all that. That line won not one but two UK elections. Opponents of austerity talked endlessly about its human impact, and got nowhere. Every UK household knew that your income largely dictates what you can spend, and as long as the analogy between that and austerity remained unchallenged talk about human impact would have little effect.

The only way to beat austerity is to question the economics on which it is based. You can start by noting that none of the textbooks used to teach economics all over the world advocate cutting public expenditure in a recession. You can add that governments have not tried to do this since the Great Depression of the 1930. If necessary you can add that the state of the art macro used by central banks also suggests cutting government spending in a deep recession will have harmful effects. You can explain why this happens, and why a Eurozone type crisis can never happen in the UK.

That does not dilute the human impact of austerity. What it does is undercut the supposed rationale for austerity on its own terms: mainstream economics. Having mainstream economics, and most mainstream economists, on your side in the debate on austerity is surely a big advantage.

Now imagine what would happen if there was no mainstream. Instead we had different schools of thought, each with their own models and favoured policies. There would be schools of thought that said austerity was bad, but there would be schools that said the opposite. I cannot see how that strengthens the argument against austerity, but I can see how it weakens it.

This is the mistake that progressives make. They think that by challenging mainstream economics they will somehow make the economic arguments for regressive policies go away. They will not go away. Instead all you have done is thrown away the chance of challenging those arguments on their own ground, using the strength of an objective empirical science.

Where UE is on stronger ground is where they question the responsibility of economists. Sticking with austerity, he notes that politicians grabbed hold of the Rogoff and Reinhart argument about a 90% threshold for government debt.

“Where was the formal, institutional denunciation of such a glaring error from the economics profession, and of the politicians who used it to justify their regressive policies? Why are R & R still allowed to comment on the matter with even an ounce of credibility? The case for austerity undoubtedly didn’t hinge on this research alone, but imagine if a politician cited faulty medical research to approve their policies — would institutions like the BMA not feel a responsibility to condemn it?”

I want to avoid getting bogged down in the specifics of this example, but instead just talk about generalities. Most economists would be horrified if some professional body started ruling on what the consensus among economists was. I would argue that this instinctive distaste is odd, as UE’s medical analogy illustrates, and also somewhat naive. I would argue that economists’ laissez faire view about defining the consensus (or lack of it) has helped the UK choose Brexit and the US choose Trump. I personally think economists need to think again about this.

However to do so would go in completely the opposite direction from what most heterodox economists wish. It would greatly increase the authority of the mainstream, when there was a consensus within that mainstream. It would formalise and make public the idea of a mainstream, and inevitably weaken those outside it.

Economics, as someone once said, is a separate and inexact science. That it is a science, with a mainstream that has areas of agreement and areas of disagreement, is its strength. It is what allows economists to claim that some things are knowledge, and should be treated as such. Turn it into separate schools of thought, and it degenerates into sets of separate opinions. There is plenty wrong with mainstream economics, but replacing it with schools of thought is not the progressive endeavor that some believe. It would just give you more idiotic policies like Brexit.

Misunderstanding macroeconomic models

The first half of this post is meant for non-economists, but it ends with a couple of points on OLG modelling

I recently wrote a post on the Eggertsson and Mehrotra paper on secular stagnation, because I thought the paper was interesting. A much more critical post from Unlearning Economics (UE) has just appeared in Pieria. UE says it “helps to illustrate the troubles faced by contemporary macroeconomics”. One of UE’s complaints seems to reflect a misunderstanding, often shared by non-economists, about what much academic macromodelling is designed to do.

UE objects to the fact that the model assumes that the amount the young can borrow (the degree of leverage) is exogenous, which means that there is no attempt to explain where this constraint on the borrowing of the young comes from. UE also complains that the model contains no banks, and no investment in physical capital. In other words, the model is much too simple. It is a natural enough idea: to explain what might be currently going on, you need a more complex model that includes everything that could be important.

There is certainly a place for this kind of more elaborate model. Christiano, Eichenbaum and Trabandt in this paper want to argue that a model based on New Keynesian theory can track what has happened over the last ten years. Their model has 40 equations. If I was trying to do a similar exercise, I would want to augment the standard New Keynesian framework with at least the following: nominal wage stickiness as well as price stickiness, a financial sector that endogenised both the cost and rationing of credit, a model of consumption which allowed for credit constraints and precautionary saving, a housing market, a model of the labour market that combined matching with rationing (as here), and something that allowed recessions to have long lasting (hysteretic) impacts on labour supply and technical progress. However large models like this will involve many macroeconomic ‘mechanisms’, and it will generally be unclear which mechanisms are important at driving particular results or explaining particular facts. We do not want to treat the elaborate model as a black box, but instead we want to understand its properties.

To understand complex models, we need much simpler models. (I once - in this paper - called the process of relating complex models to simpler models ‘theoretical deconstruction’.) In fact it is often sensible to start with the simpler model. For example, a particular issue with secular stagnation is to show how the natural real interest rate can be negative for decades rather than years (i.e. beyond the Keynesian short term)? What mechanism can do this? As I explained in my post, neither a standard representative agent model nor a standard two period overlapping generations model (OLG model, where the two generations are those earning and those retired) will give you that result. What Eggertsson and Mehrotra show is that a very simple three period OLG model (which adds a young generation that borrows) where borrowing by the young is constrained (they would like to borrow more but cannot) can provide just that mechanism.

That is a key point of the paper. The paper is not designed to explain where borrowing constraints come from: there is now a big literature on that. Thankfully the authors do not feel compelled to microfound these constraints. Instead the paper simply offers and explores a mechanism whereby an increase in these borrowing constraints could move the natural interest rate into negative territory, and for it to stay there. Having established that result, it is for subsequent work (which the authors intend to do) to see if that mechanism survives complicating the model, by for example adding investment.

Suppose the endeavour is successful, and a more complex but realistic model is able to provide an account of secular stagnation that includes other important mechanisms and which is based on a realistic set of parameter values. That would be a success, but those not familiar with all the work would ask: why does this model allow real interest rates to be negative when the standard models we know do not. The reply would be that the three period OLG structure was critical, and to see why have a look at the original, simple model.

Now you might say the authors should wait until they have built the more realistic model before creating what could turn out to be a research path that might fail to achieve its goal. That would be quite wrong, because the more debate there is within the academic community when ideas are at their early stages the better. I want to give an example of this, but here I will go into territory that will probably only interest macroeconomists.

It might be the case, for example, that the authors intuition that their results will survive introducing other assets like physical capital can be shown to be wrong very quickly. Indeed, Nick Rowe has already made such a claim, arguing that the presence of land as an asset ensures a positive real interest rate. If Nick was right this could be enough to kill the research programme, without any more time being wasted. Whether he is right is another matter: this paper by Rhee may be relevant in that respect.

Here I just want to add a final thought. Within an OLG framework, it may not be necessary to establish the existence of a steady state with negative real interest rates. The typical period in an OLG model lasts two or more decades. So if the dynamics of such a model involved some overshooting, it might be possible to generate prolonged periods (in years) of negative interest rates even if the steady state real interest rate was positive. To be honest I’m not sure what might give rise to overshooting of this kind, but that may just reflect my inadequate imagination.