Posts Tagged Macroeconomics

The Crisis & Economics, Part 6: “Oh, You Just Mean Macro”

This is part 6 in my series on how the financial crisis is relevant for economics (here are parts 1, 2, 34 & 5). Each part explores an argument economists have made against the charge that the crisis exposed fundamental failings of their discipline. This post discusses the argument that the ‘crisis in economics’ is confined only to macroeconomics, which is actually minority, so attacking all of economics is wrongheaded.

Argument #6: “Sure, modern macroeconomics is pretty weak. But most economists don’t even work on macro, so they are unaffected.”

Quite a lot of economists consider the debate about the financial crisis irrelevant to what they do. After all, why should a crisis at the macro level invalidate econometrics, game theory or auction theory? Attacking these fields and others for the recession is like blaming mechanical engineers for a bridge collapse. In fact, many economists hold macro in the same (low) esteem as the public: Daniel Hamermesh goes so far as to claim that “most of what the macro guys do in academia is just worthless rubbish”, but adds that the kind of field he works in “has contributed tremendously and continues to contribute”. Even the discipline’s most vehement defenders are willing to concede macroeconomics is bunk.

There is a considerable amount of truth to this view. While there may be critiques of all areas in economics, the claim that the financial crisis is what’s thrown them into disrepute is a non sequitur. Critics should therefore be careful to distinguish macroeconomists from their colleagues when (rightly) dismissing the former’s failure to deal with the crisis. Nevertheless, there are two major ways in which the failings of macroeconomics are symptomatic of more general problems with economic theory, so the discipline as a whole cannot be let off the hook.

The first is a lack of holism. A large amount of economic theories are built in an abstract theoretical vacuum, with little reference to what is happening around the individual agent. But the importance of the macroeconomy for behaviour in specific sectors or by specific actors cannot be ignored. For example, if you drop the macroeconomic assumption of full employment, this affects theories in areas from public goods provision to labour markets to Walrasian equilibrium. Consumers’ and firms’ expectations are strongly informed by the macroeconomic and political environment around them. Considering the effects of political institutions such as unions on the labour market, but ignoring their broader political role, can create narrow and misguided conclusions about their efficacy. New Institutional economics often takes ‘institutions’ as exogenous, failing to consider to two-way interaction between institutions and agents. The in-vogue ‘Randomised Control Trial’ restricts the economic environment to such a degree that it’s questionable whether one can generalise the results at all. And so forth.

Don’t get me wrong: there is an obvious case for different areas of economics being separate from one another: taking certain parameters as exogenous to look at a certain area, and using different tools for different areas. But even the most specialised fields should never forget the broader scope and context of their ideas, and this should be reflected in the theoretical approach. Thomas Piketty’s Capital is a shining example of how to intertwine theory, history, statistics and politics to build a better understanding of capitalism. Another is the attempt by ecological economists to place the economy in its environmental context, rather than simply taking resource endowments as a given and assuming pollution just sort of…disappears, save for its monetary cost. Minsky’s Financial Instability Hypothesis shows one way to make an effective link between the behaviour of investors and broader economic performance, integrating finance and macroeconomics. Overspecialisation may cause economists to miss these key insights.

The second issue is that many of the problems with macroeconomics can be applied to, or are relevant for, other areas of the discipline. One of the key complaints about macroeconomics – that it relies on microfoundations – is a problem precisely because it imports unrealistic assumptions about economic behaviour from microeconomics. The problem of having an abundance of abstract models, each seeking to explain one or two ‘things’, but with no real way to tell which model is applicable and when, applies not just to macroeconomics but also to behavioural economics, microeconomics, oligopoly theory. Endogenous money, which is central to macroeconomists’ lack of understanding of the crisis, also has major implications for finance. To reuse my above analogy, you might well be concerned about mechanical engineers after a bridge collapse if they largely relied on the same methods used by the civil engineers.

Your average economist is probably right to point out that the public’s ire should be focused not on them, but on macroeconomics. However, this doesn’t mean that they are immune from the serious questions the crisis raised about the methodology, assumptions and ethics of the field. It’s a case-by-case matter which areas are impacted and by how much, but any attempt to box off macroeconomic theory entirely should be resisted. There’s plenty of room for fruitful debate about all areas of economic theory, much of which will benefit from being informed by the shortcomings of economic theory as exposed by the financial crisis.

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The Crisis & Economics, Part 5: “Shhh! We’re Working On It”

This is part 5 in my series on how the financial crisis is relevant for economics (parts 1, 2, 3 & 4 are here). Each part explores an argument economists have made against the charge that the crisis exposed fundamental failings of their discipline. This post explores the possibility that macroeconomics, even if it failed before the crisis, has responded to its critics and is moving forward.

Argument #5: “We got this one wrong, sure, but we’ve made (or are making) progress in macroeconomics, so there’s no need for a fundamental rethink.”

Many macroeconomists deserve credit for their mea culpa and subsequent refocus following the financial crisis. Nevertheless, the nature of the rethink, particularly the unwillingness to abandon certain modelling techniques and ideas, leads me to question whether progress can be made without a more fundamental upheaval. To see why, it will help to have a brief overview of how macro models work.

In macroeconomic models, the optimisation of agents means that economic outcomes such as prices, quantities, wages and rents adjust to the conditions imposed by input parameters such as preferences, technology and demographics. A consequence of this is that sustained inefficiency, unemployment and other chaotic behaviour usually occur when something ‘gets in the way’ of this adjustment. Hence economists introduce ad hoc modifications such as sticky prices, shocks and transaction costs to generate sub-optimal behaviour: for example, if a firm’s cost of changing prices exceeds the benefit, prices will not be changed and the outcome will not be Pareto efficient. Since there are countless ways in which the world ‘deviates’ from the perfectly competitive baseline, it’s mathematically troublesome (or impossible) to include every possible friction. The result is that macroeconomists tend to decide which frictions are important based on real world experience: since the crisis, the focus has been on finance. On the surface this sounds fine – who isn’t for informing our models with experience? However, it is my contention that this approach does not offer us any more understanding than would experience alone.

Perhaps an analogy will illustrate this better. I was once walking past a field of cows as it began to rain, and I noticed some of them start to sit down. It occurred to me that there was no use them doing this after the storm started; they are supposed to give us adequate warning by sitting down before it happens. Sitting down during a storm is just telling us what we already know. Similarly, although the models used by economists and policy makers did not predict and could not account for the crisis before it happened, they have since built models that try to do so. They generally do this by attributing the crisis to frictions that revealed themselves to be important during the crisis. Ex post, a friction can always be found to make models behave a certain way, but the models do not make identifying the source of problems before they happen any easier, and they don’t add much afterwards, either – we certainly didn’t need economists to tell us finance was important following 2008. In other words, when a storm comes, macroeconomists promptly sit down and declare that they’ve solved the problem of understanding storms.  It becomes difficult to escape the circularity of defining the relevant friction by its outcome, hence stripping the idea of ‘frictions’ of predictive power or falsifiability.

There is also the open question of whether understanding the impact of a ‘friction’ relative to a perfectly competitive baseline entails understanding its impact in the real world. As theorists from Joe Stiglitz to Yanis Varoufakis have argued, neoclassical economics is trapped in a permanent fight against indeterminacy: the quest to understand things relative to a perfectly competitive, microfounded baseline leads to aggregation problems and intractable complexities that, if included, result in “anything goes” conclusions. To put in another way, the real world is so complex and full of frictions that whichever mechanics would be driving the perfectly competitive model are swamped. The actions of individual agents are so intertwined that their aggregate behaviour cannot be predicted from each of their ‘objective functions’. Subsequently, our knowledge of the real world must be informed by either models which use different methodologies or, more crucially, by historical experience.

Finally, the ad hoc approach also contradicts another key aspect of contemporary macroeconomics: microfoundations. The typical justification for these is that, to use the words of the ECB, they impose “theoretical discipline” and are “less subject to the Lucas critique” than a simple VAR, Old Keynesian model or another more aggregative framework. Yet even if we take those propositions to be true, the modifications and frictions that are so crucial to making the models more realistic are often not microfounded, sometimes taking the form of entirely arbitrary, exogenous constraints. Even worse is when the mechanism is profoundly unrealistic, such as prices being sticky because firms are randomly unable to change them for some reason. In other words, macroeconomics starts by sacrificing realism in the name of rigour, but reality forces it in the opposite direction, and the end result is that it has neither.

Macroeconomists may well defend their approach as just a ‘story telling‘ approach, from which they can draw lessons but which isn’t meant to hold in the same manner as engineering theory. Perhaps this is defensible in itself, but (a) personally, I’d hope for better and (b) in practice, this seems to mean each economists can pick and choose whichever story they want to tell based on their prior political beliefs. If macroeconomists are content conversing in mathematical fables, they should keep these conversations to themselves and refrain from forecasting or using them to inform policy. Until then, I’ll rely on macroeconomic frameworks which are less mathematically ‘sophisticated’, but which generate ex ante predictions that cover a wide range of observations, and which do not rely on the invocation of special frictions to explain persistent deviations from these predictions.

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The Crisis & Economics, Part 3: Econoracles

This is part 3 in my series on why and how the 2008 financial crisis is relevant to economics. The first instalment discussed why the good times during the boom are no excuse for the bad times during the bust. The second instalment discussed use of the Efficient Markets Hypothesis (EMH) to defend economists’ inability to forecast the movements of financial markets. This instalment discusses the more general proposition that crises are events whose prediction is outside the grasp of anyone, including economists.

Argument #3: “Economists aren’t oracles. Just as seismologists don’t predict earthquakes and meteorologists don’t predict the weather, we can’t be expected to predict recessions.”

This argument initially sounds quite persuasive: the economy is complex, and the future inherently unknowable, so we shouldn’t expect economists to predict the future any better than we’d expect from other analysts of complex systems. However, the argument is actually a straw man of what critics mean when they say economists didn’t foresee the recent crisis. It confuses conditional predictions of the form “if you don’t do something about x, y might happen” with oracle-esque predictions of the form “y is going to happen on December 2003”. Nobody should have expected the details of crisis – many of which were hidden – to be foreseen, and much less a prediction about exactly which banks would fail and when. Instead, what is expected is for economists to have the key indicators right and know how to deal with them, to be alert to the possibility of crisis at all times – even in seemingly tranquil periods – and to have measures in place to cushion the blow should a crisis occur.

In fact, those who study earthquakes or hurricanes do ‘predict’ them in the above sense: they understand where they’re most likely to occur (for example near fault lines), and at roughly which frequency, time and magnitude. They also have an idea of how best to combat them: areas which are prone to earthquakes and hurricanes – funding permitting – have dwellings built in such a way that they can withstand such occurrences. They understand why disasters happen, and their models tell us why they cannot be predicted. For example, it is common knowledge that weather forecasts get less accurate the further away they are due to the sensitivity of the model to initial conditions, a point based on complex mathematics but communicated well by meteorologists (not to mention that weather forecasts are improving all the time).

While there’s been a lot of kerfuffle over exactly who ‘predicted’ the crisis and what that means, the most important point is that those who did warn of a crisis like the one we’re going through identified key mechanisms (debt build up, asset price bubbles, global imbalances) and argued that, unless these processes were combated, we’d be in danger. I appreciate that the ‘stopped clock’ problem really is a problem: there are so many people predicting crises that eventually, one of them will seem to be right. However, this is easily countered by using the same framework to make predictions outside the crisis (predictions in the general sense of the word, not just about the future). For example, Peter Schiff predicted a financial crisis quite a lot like the one we’ve been through, but he also predicted hyperinflation, suggesting that his model is wrong in some way. Conversely, endogenous money models are consistent with both the financial crisis and the subsequent weak effects of monetary stimulus: since money is created as debt, private debt can have major effects on the economy, and since banks do not lend based on reserves, there’s no reason for an increased monetary base do produce inflation.

Finally, while natural disasters are almost entirely exogenous phenomena, the economy is a social system, so we have a degree of control over it, both individually and collectively. It’s perhaps a testament to how the neoclassical approach naturalises the economic system that some economists feel recessions can be compared to natural disasters (not that this would mean they had no responsibility for alleviating their effects). Since economic models are frequently used to inform government policy, it’s quite clear that economists appreciate this point; however, since they often admit they don’t really understand what causes recessions, they are doing the equivalent of sending us up in toy planes. It’s fair to say that you don’t fully understand the economy; it’s quite another thing to say this, then recommend ways to manage it. But the relationship between economists and policy is a matter for the next part of the series.

The next instalment will be part 4: masters of the universe?

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Pieria: How Not to Do Macroeconomics, Part II

I have  new post on Pieria, following up on mainstream macro and secular stagnation. The beginning is a restatement of my critique of EM/a response to Simon Wren-Lewis, but the main nub of the post is (hopefully) a more constructive effort at macroeconomics, from a heterodox perspective:

There are two major heterodox theories which help to understand both the 2008 crisis and the so-called period of ‘secular stagnation’ before and after it happened: Karl Marx’s Tendency of the Rate of Profit to Fall (TRPF), and Hyman Minsky’s Financial Instability Hypothesis (FIH)I expect that neither of these would qualify as ‘precise’ or ‘rigorous’ enough for mainstream economists – and I’ve no doubt the mere mention of Marx will have some reaching for the Black Book of Communism – but the models are relatively simple, offer an understanding of key mechanisms and also make empirically testable predictions. What’s more, they do not merely isolate abstract mechanisms, but form a general explanation of the trends in the global economy over the past few decades (both individually, but even moreso when combined). Marx’s declining RoP serves as a material underpinning for why secular stagnation and financialisation get started, while Minsky’s FIH offers an excellent description of how they evolve.

I have two points that I wanted to add, but thought they would clog up the main post:

First, in my previous post, I referenced Stock-Flow Consistent models as one promising future avenue for fully-fledged macroeconomic modelling, a successor to DSGE. Other candidates might include Agent-Based Modelling, models in econophysics or Steve Keen’s systems dynamics approach. However, let me say that – as far as I’m aware – none of these approaches yet reach the kind of level I’m asking of them. I endorse them on the basis that they have more realistic foundations, and have had fewer intellectual resources poured into them than macroeconomic models, so they warrant further exploration. But for now, I believe macroeconomics should walk before it can run: clearly stated, falsifiable theories, which lean on maths where needed but do not insist on using it no matter what, are better than elaborate, precisely stated theories which are so abstract it’s hard to determine how they are relevant at all, let alone falsify them.

Second, these are just two examples, coloured no doubt by my affiliation with what you might call left-heterodox schools of thought. However, I’m sure Austrian economics is quite compatible with the idea of secular stagnation, since their theory centres around how credit expansion and/or low interest rates cause a misallocation of investment, resulting in unsustainable bubbles. I leave it to those more knowledgeable about Austrian economics than me to explore this in detail.

 

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How Not to Do Macroeconomics

A frustrating recurrence for critics of ‘mainstream’ economics is the assertion that they are criticising the economics of bygone days: that those phenomena which they assert economists do not consider are, in fact, at the forefront of economics research, and that the critics’ ignorance demonstrates that they are out of touch with modern economics – and therefore not fit to criticise it at all.

Nowhere is this more apparent than with macroeconomics. Macroeconomists are commonly accused of failing to incorporate dynamics in the financial sector such as debt, bubbles and even banks themselves, but while this was true pre-crisis, many contemporary macroeconomic models do attempt to include such things. Reputed economist Thomas Sargent charged that such criticisms “reflect either woeful ignorance or intentional disregard for what much of modern macroeconomics is about and what it has accomplished.” So what has it accomplished? One attempt to model the ongoing crisis using modern macro is this recent paper by Gauti Eggertsson & Neil Mehrotra, which tries to understand secular stagnation within a typical ‘overlapping generations’ framework. It’s quite a simple model, deliberately so, but it helps to illustrate the troubles faced by contemporary macroeconomics.

The model

The model has only 3 types of agents: young, middle-aged and old. The young borrow from the middle, who receive an income, some of which they save for old age. Predictably, the model employs all the standard techniques that heterodox economists love to hate, such as utility maximisation and perfect foresight. However, the interesting mechanics here are not in these; instead, what concerns me is the way ‘secular stagnation’ itself is introduced. In the model, the limit to how much young agents are allowed to borrow is exogenously imposed, and deleveraging/a financial crisis begins when this amount falls for unspecified reasons. In other words, in order to analyse deleveraging, Eggertson & Mehrotra simply assume that it happens, without asking why. As David Beckworth noted on twitter, this is simply assuming what you want to prove. (They go on to show similar effects can occur due to a fall in population growth or an increase in inequality, but again, these changes are modelled as exogenous).

It gets worse. Recall that the idea of secular stagnation is, at heart, a story about how over the last few decades we have not been able to create enough demand with ‘real’ investment, and have subsequently relied on speculative bubbles to push demand to an acceptable level. This was certainly the angle from which Larry Summers and subsequent commentators approached the issue. It’s therefore surprising – ridiculous, in fact – that this model of secular stagnation doesn’t include banks, and has only one financial instrument: a risk-less bond that agents use to transfer wealth between generations. What’s more, as the authors state, “no aggregate savings is possible (i.e. there is no capital)”. Yes, you read that right. How on earth can our model understand why there is not enough ‘traditional’ investment (i.e. capital formation), and why we need bubbles to fill that gap, if we can have neither investment nor bubbles?

Naturally, none of these shortcomings stop Eggertson & Mehrotra from proceeding, and ending the paper in economists’ favourite way…policy prescriptions! Yes, despite the fact that this model is not only unrealistic but quite clearly unfit for purpose on its own terms, and despite the fact that it has yielded no falsifiable predictions (?), the authors go on give policy advice about redistribution, monetary and fiscal policy. Considering this paper is incomprehensible to most of the public, one is forced to wonder to whom this policy advice is accountable. Note that I am not implying policymakers are puppets on the strings of macroeconomists, but things like this definitely contribute to debate – after all, secular stagnation was referenced by the Chancellor in UK parliament (though admittedly he did reject it). Furthermore, when you have economists with a platform like Paul Krugman endorsing the model, it’s hard to argue that it couldn’t have at least some degree of influence on policy-makers.

Now, I don’t want to make general comments solely on the basis of this paper: after all, the authors themselves admit it is only a starting point. However, some of the problems I’ve highlighted here are not uncommon in macro: a small number of agents on whom some rather arbitrary assumptions are imposed to create loosely realistic mechanics, an unexplained ‘shock’ used to create a crisis. This is true of the earlier, similar paper by Eggertson & Krugman, which tries to model debt-deflation using two types of agents: ‘patient’ agents, who save, and ‘impatient agents’, who borrow. Once more, deleveraging begins when the exogenously imposed constraint on the patient agent’s borrowing falls For Some Reason, and differences in the agents’ respective consumption levels reduce aggregate demand as the debt is paid back. Again, there are no banks, no investment and no real financial sector. Similarly, even the far more sophisticated Markus K. Brunnermeier & Yuliy Sannikov – which actually includes investment and a financial sector – still only has two agents, and relies on exogenous shocks to drive the economy away from its steady-state.

Whither macroeconomics?

Why do so many models seem to share these characteristics? Well, perhaps thanks to the Lucas Critique, macroeconomic models must be built up from optimising agents. Since modelling human behaviour is inconceivably complex, mathematical tractability forces economists to make important parameters exogenous, and to limit the number (or number of types) of agents in the model, as well as these agents’ goals & motivations. Complicated utility functions which allow for fairly common properties like relative status effects, or different levels of risk aversion at different incomes, may be possible to explore in isolation, but they’re not generalisable to every case or the models become impossible to solve/indeterminate. The result is that a model which tries to explore something like secular stagnation can end up being highly stylised, to the point of missing the most important mechanics altogether. It will also be unable to incorporate other well-known developments from elsewhere in the field.

This is why I’d prefer something like Stock-Flow Consistent models, which focus on accounting relations and flows of funds, to be the norm in macroeconomics. As economists know all too well, all models abstract from some things, and when we are talking about big, systemic problems, it’s not particularly important whether Maria’s level of consumption is satisfying a utility function. What’s important is how money and resources move around: where they come from, and how they are split – on aggregate – between investment, consumption, financial speculation and so forth. This type of methodology can help understand how the financial sector might create bubbles; or why deficits grow and shrink; or how government expenditure impacts investment. What’s more, it will help us understand all of these aspects of the economy at the same time. We will not have an overwhelming number of models, each highlighting one particular mechanic, with no ex ante way of selecting between them, but one or a small number of generalisable models which can account for a large number of important phenomena.

Finally, to return to the opening paragraph, this paper may help to illustrate a lesson for both economists and their critics. The problem is not that economists are not aware of or never try to model issue x, y or z. Instead, it’s that when they do consider x, y or z, they do so in an inappropriate way, shoehorning problems into a reductionist, marginalist framework, and likely making some of the most important working parts exogenous. For example, while critics might charge that economists ignore mark-up pricing, the real problem is that when economists do include mark-up pricing, the mark-up is over marginal rather than average cost, which is not what firms actually do. While critics might charge that economists pay insufficient attention to institutions, a more accurate critique is that when economists include institutions, they are generally considered as exogenous costs or constraints, without any two-way interaction between agents and institutions. While it’s unfair to say economists have not done work that relaxes rational expectations, the way they do so still leaves agents pretty damn rational by most peoples’ standards. And so on.

However, the specific examples are not important. It seems increasingly clear that economists’ methodology, while it is at least superficially capable of including everything from behavioural economics to culture to finance, severely limits their ability to engage with certain types of questions. If you want to understand the impact of a small labour market reform, or how auctions work, or design a new market, existing economic theory (and econometrics) is the place to go. On the other hand, if you want to understand development, historical analysis has a lot more to offer than abstract theory. If you want to understand how firms work, you’re better off with survey evidence and case studies (in fairness, economists themselves have been moving some way in this direction with Industrial Organisation, although if you ask me oligopoly theory has many of the same problems as macro) than marginalism. And if you want to understand macroeconomics and finance, you have to abandon the obsession with individual agents and zoom out to look at the bigger picture. Otherwise you’ll just end up with an extremely narrow model that proves little except its own existence.

 

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