Simon Wren-Lewis on New Classical Economics and the Financial Crisis

New paper by Wren-Lewis titled "Unravelling the New Classical Counter Revolution." It provides a strong New Keynesian critique of the New Classical/Real Business Cycle schools. He argues, correctly in my view, that the problem is the abandoning of the Keynesian method of analysis. I'm less keen on microfoundations. Or at least on marginalist microfoundations. But it is important to understand how much the fundamentalist views of Lucas and Prescott have affected the profession.

From the abstract:

To understand the position of Keynes's The General Theory today, and why so many policy-makers felt they had to go back to it to understand the Great Recession, we need to understand the New Classical Counter Revolution (NCCR), and why it was so successful. This revolution can be seen as having two strands. The first, which attempted to replace Keynesian policy, failed. The second, which was to change the way academic macroeconomics was done, was successful. Before the NCCR, macroeconomics was an intensely empirical discipline: something made possible by the developments in statistics and econometrics inspired by The General Theory. After the NCCR and its emphasis on microfoundations, it became much more deductive. 

As a result, most academic macroeconomists today would see the foundation of their discipline as not coming from The General Theory, but as coming from basic microeconomic theory – arguably the ‘classical theory’ that Keynes was so keen to cast aside. Students are also taught that pre-NCCR methods of analysing the economy are fatally flawed, and that simulating DSGE models is the only proper way of doing policy analysis. This is simply wrong. The problem with the NCCR was not the emergence of microfoundations modelling, which is a progressive research programme, but that it discouraged the methods of analysis that had flourished after The General Theory. I argue that, had there been more academic interest in these alternative forms of analysis, the discipline would have been better prepared ahead of the financial crisis.

Read the whole paper here. 

Notes on the Policy Implications of the New Macroeconomic Consensus

The New Macroeconomic Consensus (NMC) model is based on three simple equations. An IS equation that, contrary to what most discussions within the heterodoxy suggest, is based on a Ramsey model intertemporal approach to savings and investment, a Phillips curve (PC) equation, normally with rational expectations, and a monetary policy (MP) rule, typically Taylor’s rule. From the IS and the MP an aggregate demand (AD) curve is derived, while the PC provides an aggregate supply (AS) curve, similar to Lucas’ supply curve. Business cycles are seen as being determined by shocks, either monetary, that affect the AD curve, or real, which impact the AS curve.

A few things are important to note with respect to the NMC model. First, the IS curve now is not based on the traditional Keynesian multiplier process, by which savings adjust to investment (or in more sophisticated models with endogenous investment, to autonomous demand) as a result of variations to the income level. Agents make intertemporal decisions on consumption and savings, and investment adjusts, in the absence of imperfections, to full employment savings as in the pre-Keynesian models. That is the reason why in order to stimulate the economy it is often suggested that what is needed is higher inflationary expectations (which in this framework could be caused by the central bank announcing a higher inflation target), which would in turn lead to an increase in current consumption (since inflation would reduce future consumption possibilities; see my critique of this view, which I refer to as the inflation expectations fairy, here).

Second, both the New Keynesian Phillips Curve and the Taylor rule presuppose the existence of a natural rate of unemployment, in line with Milton Friedman. Further, stabilizing the rate of inflation around its target is tantamount to stabilizing output around its full employment level, a result sometimes referred to as the ‘Divine Coincidence.’ Thus, inflation is always the result of a level of unemployment that is below its natural level, or in other words caused by demand-pull. Supply-side shocks may eventually cause inflation too, but those are seen, at least by most New Keynesians as being of secondary importance. Even Lucas, who has accepted for the most part the Real Business Cycle story, admits that one cannot explain the Great Depression and other such crises with real shocks.

Third, the MP rule implies that money is endogenous, and that central banks control the rate of interest and NOT the quantity of money. In other words, the old Monetarist rules about the rate of growth of money supply are out, since actual central banks very rarely have behaved in that way. This ‘innovation’ (not much of an invention since Wicksell used more than a century ago) within the mainstream took place without ever acknowledging the contributions of Kaldor (accomodationist tradition to endogenous money), Minsky (financial innovation tradition to endogenous money), Moore and other post-Keynesian authors.

Finally, it is rather clear that the NMC is essentially a neo-Wicksellian model (for a simple description go here), rather than Keynesian (New or otherwise). Not only the multiplier model was abandoned (and with it even the basis for fiscal policy activism, since the logic of Barro’s Ricardian Equivalence has been incorporated; see Wren-Lewis here), but also the concept of the natural rate that Keynes at least tried to get rid of has become central for policy analysis. And here is the Achilles’ heel of the NMC model.

Note that if the natural rate is not fixed, and in particular if it presents hysteresis or path dependence, and moves with the actual level of unemployment, then the basis of the NMC model falls apart. In other words, expanding demand might reduce the natural rate of unemployment and would not trigger inflation, and as a result would not require the central bank to hike the rate of interest to lean against the wind. That was, in a sense, the rationale for not hiking the rate of interest when unemployment fell below 6%, which many identified as the natural rate, during the Clinton boom. Greenspan suggested that productivity was going up (note that he didn’t necessarily say that productivity went up, and the natural rate down, as a result of the expansion of demand).

There are good logical reasons for not believing the natural rate story, as we know, associated to the limitations of the marginalist theory (see here). However, there are also reasonably well-established empirical problems with the natural rate hypothesis. The Real Business Cycles authors, in particular Nelson and Plosser in their classic paper (here), have long ago shown that output follows a random walk. In other words, changes in output are permanent, and there is no tendency for output to revert to its former trend following a shock, contradicting the natural rate hypothesis, or suggesting if one prefers that the natural rate moves with supply-side shocks and that the business cycle is the result of agents adjusting their behavior to the change in the natural rate.

As I noted before (here), the actual measure of productivity (Total Factor Productivity, TFP) used by RBC authors does NOT measure productivity, and most of their conclusions are irrelevant really. Also, as suggested above, it would be impossible to pin down the real shock that caused the Great Depression or the Great Recession, that have structural causes that are profound (in the patterns of consumption, private indebtedness and inequality) and that were triggered by financial shocks. However, the notion that the natural rate is not fixed, and that it changes significantly is actually quite important, since as we indicated, it suggests that policies that try to lean against the wind hiking the rate of interest when the economy is below the natural rate of unemployment are without foundation.

Heterodox authors would add to the RBC empirical observation about the fact that output is not mean reverting, that the supply or capacity limit of the economy is endogenously determined by autonomous spending (the supermultiplier that extends Keynes’ effective demand to explain potential output; for more go here). This does NOT mean that one can expand the economy without limits, since if the expansion of demand is faster than the movement of the capacity limit, eventually full employment would be reached and inflation (demand-pull inflation) might follow. Note, however, than since the 1930s in the US unemployment was below 4% (to say a relatively low number) only for four short periods, during the mid-40s, early 50s, late 60s and late 90s, with inflation occurring in the first three periods. Also, it suggests that the main barrier to the use of demand policies to achieve full employment, at least in developed countries with no balance of payments problems, is political. As Kalecki noted long ago, sound finance would be the political instrument to keep workers’ demands for higher wages in line. The NMC model is the modern incarnation of what Kalecki’s referred to as sound finance. So who is really surprised with the dominance of austerity policies?

More on Wren-Lewis flimflam according to Palley

Simon Wren-Lewis replied to Tom's previous post on the flimflam defense of mainstream economics and says he cannot find it (the flimflam). Tom provides in a new post some hints on where to look. Note that Tom raises two points, among others, always emphasized in this blog. Namely:

Marginal productivity theory remains at the core of mainstream distribution and production theory. However, marginal productivity can be adjusted for imperfect competition to yield, what might be called, adjusted marginal products. Thereafter, things remain analytically very similar and those adjusted marginal products then determine the stock demand for capital and drive long-run capital accumulation. 

The imperfect competition model of so-called New Keynesians continues to assert price and nominal wage flexibility would restore full employment. In a financialized economy with massive inside debts, that strikes me as an implausible proposition.

Both require to be solved and provide a real alternative that the notion of the natural rate is abandoned. Note that this would strengthen Wren-Lewis and other New Keynesian arguments.

Palley on the flimflam defense of mainstream economics

By Thomas Palley

The teaching of economics has recently been in the news. One reason is the activities of Manchester University undergraduates who have formed the Post-Crash Economics Society to protest the monopoly of mainstream neoclassical economics in university lecture halls. A second reason is criticism of the neoclassical reasoning in Thomas Piketty’s runaway best seller Capital in the Twenty-First Century.

This criticism and calls for including heterodox economic theory in the curriculum have prompted a defense of mainstream economics from Princeton University’s Paul Krugman and Oxford University’s Simon Wren-Lewis. Both hail from the mainstream’s liberal wing, which muddies the issue because it is easy to conflate the liberal wing with the critics. In fact, the two are significantly different and their defense of mainstream economics is pure flimflam.

Read more here.

Lars P. Syll: Krugman dismisses heterodox economics students

By Lars P. Syll

Paul Krugman today rides out — like his brother in arms, Simon Wren-Lewis — to defend mainstream economics. According to Krugman, yours truly and others of that ilk are wrong in blaming mainstream economics for not being relevant and not being able to foresee the crisis. To Krugman there is nothing wrong with “standard theory” and “economics textbooks.” If only policy makers and economists stick to “standard economic analysis” everything would be just fine. I’ll be dipped! If there’s anything the last five years have shown us, it is that economists have gone astray in their shed of tools. Krugman’s “standard theory” — neoclassical economics – has contributed to causing todays’s economic crisis rather than to solving it. [...] So now all you young economics students that want to see a real change in economics and the way it’s taught — now you know where you have Krugman & Co. If you really want something other than the same old neoclassical catechism, if you really don’t want to be force-fed with neoclassical mumbo jumbo, you have to look elsewhere.

Read the rest here.

Lars Syll on Krugman, Wren-Lewis and the New Keynesian apologetics

By Lars P. Syll

Is academic (mainstream neoclassical) macroeconomics flourishing? “New Keynesian” macroeconomist Simon Wren-Lewis had a post up not that long ago on his blog, answering the question affirmatively:

Consider monetary policy. I would argue that we have made great progress in both the analysis and practice of monetary policy over the last forty years … However, it has to be acknowledged that policymakers who look at the evidence day in and day out believe that New Keynesian theory is the most useful framework currently around. I have no problem with academics saying ‘I know this is the consensus, but I think it is wrong’. However to say ‘the jury is still out’ on whether prices are sticky is wrong. The relevant jury came to a verdict long ago… 

It is obvious that when it comes to using fiscal policy in short term macroeconomic stabilisation there can be no equivalent claim to progress or consensus. The policy debates we have today do not seem to have advanced much since when Keynes was alive… 

What has been missing with fiscal policy has been the equivalent of central bank economists whose job depends on taking an objective view of the evidence and doing the best they can with the ideas that academic macroeconomics provides…The contrast between monetary and fiscal policy tells us that this failure is not an inevitable result of the paucity of evidence in macroeconomics. I think it has a lot more to do with the influence of ideology…

And today another sorta-kinda “New Keynesian” — Paul Krugman — has a post up arguing that the problem with the academic profession is that some macroeconomists aren’t “bothered to actually figure out” how the New Keynesian model with its Euler conditions — ”based on the assumption that people have perfect access to capital markets, so that they can borrow and lend at the same rate” — really works. According to Krugman, this shouldn’t be hard at all — “at least it shouldn’t be for anyone with a graduate training in economics.”

Read the rest here.

The other Dutch Disease

Simon Wren-Lewis and Paul Krugman have written complaining about Dutch contractionary policies, noting, as should be obvious to any reasonable observer, that is is a huge mistake. Graph below shows Dutch rates of growth, and it's clear that the economy is in a recession (the estimate for 2012 growth rate is from here).

Funny thing, if you look at the 1960s, the period of the infamous Dutch Disease, when the discovery of natural gas supposedly impacted negatively the Dutch manufacturing sector (and should have had a negative effect on productivity and growth), then you see that the economy was doing way better than in the post-1973 period. Perhaps we should rename the disease associated with financial liberalization, and monetary policy focused only on inflation (and the austerity policies that often go hand in hand) as the real Dutch Disease.

On the state of macroeconomics: fashion versus logic and evidence

Yes there is something rotten in the kingdom of Denmark, and it is macroeconomics; pretty much as in every other country. There has been an ongoing debate on the blogosphere on the topic (see Krugman, Smith, Thoma, Williamson and Wren-Lewis, not in chronological order, by the way). The New Classical versus New Keynesian debate tends to be on two issues the relevance of microfoundations on the theoretical level, and the importance of price rigidities on the empirical side.

Scientists, as Mankiw put it, are the New Classicals that emphasize the microfundations. They have intertemporal maximization models based on rational representative agents. The New Keynesians are the engineers, again using Mankiw's dichotomy, that strive for economic realism. Or so is what you are expected to believe if you read their posts. Of course all of these presumptions are bogus.

Noah Smith correctly points out that they all use the same DSGE models. But Krugman notes that on policy debates the whole difference is based on the assumption of sticky prices. So they use the same models, but reach very different conclusions. Of course the tools are not neutral though. Using DSGE models has hurt the positions that New Keynesian want to take. For example, Krugman has been forced to argue that the reason for the poor recovery is that the natural rate of interest is negative (and hence the current rate is too high to bring investment and savings into equilibrium).

This is a much weaker position than the one taken by heterodox authors that suggest that the crisis is due to lack of demand associated to worsening income distribution over the last three decades, and the consequent expansion of unsustainable private debt to allow for consumption. So the poor recovery is associated to lack of demand, since wages are stagnant and private debt cannot increase (and the GOP is bent in not allowing public demand to grow).

Note that the Godley type models, which follow the heterodox perspective, were much better for understanding and foreseeing the crisis (see here). There is no reason for intertemporal maximization models, and their kind of microeconomics (Sraffians have better stuff for that). New Classicals, Mankiw notwithstanding, are not scientists (or at least not good ones), since their models do have significant logical problems, and you cannot be a good engineer, somebody concerned with practical applications of scientific knowledge, if you share a model that is flawed.

On an interesting note, Krugman's main complain about Noah Smith's position is that he doesn't understand that the New Classicals have basically treated New Keynesians as outcasts. In his words:

"the freshwater [New Classical] types simply didn’t accept the legitimacy of what the New Keynesians were doing — in fact, didn’t even bother to read any of it, because anyone who actually worked with that kind of model would know that fiscal policy can indeed have an effect in that framework."

The problem is that they don't think he is legitimate. In fact, that is true. Williamson says:

"It doesn't surprise me that Paul Krugman isn't up on what is going on in macroeconomic research. Why should we expect him to go to macro conferences, spend time in seminars, and talk to his colleagues at Princeton? He has plenty on his plate, what with delivering two NYT columns per week, blogging, talking to pundits, and giving speeches. But if he's not up on the field, what purpose does it serve to make up outlandish stuff for people to read?"

Indeed Williamson's critique is that Krugman is not up to date, on the cutting edge, Colander would say. So he has missed the last fashion season in macroeconomics. And Wren-Lewis makes a point that he is a Karl Lagerfeld of macroeconomics (not sure if that is a correct fashion quote). Wren-Lewis points out that:

PK [yes, Paul Krugman] was very much at the forefront of analysing the Zero Lower Bound problem, before that problem hit most of the world. While many point to Mike Woodford’s Jackson Hole paper as being the intellectual inspiration behind recent changes at the Fed, the technical analysis can be found in Eggertsson and Woodford, 2003. That paper’s introduction first mentions Keynes, and then Krugman’s 1998 paper on Japan. Subsequently we have Eggertsson and Krugman (2010), which is part of a flourishing research programme that adds ‘financial frictions’ into the New Keynesian model. You would not think of suggesting that PK is out of touch unless you are in effect dismissing or marginalising this whole line of research.

So he is pretty much au courant, according to his New Keynesian friends (and that sounds right to me too, by the way). No fashion problem with Krugman and New Keynesians. They are trendy too. Good for them.

Yet, what it is expected of science is not fashion, but relevance following logic and evidence. And yes Krugman is right, there is evidence for price rigidity, and also no evidence for the sort of theory of distribution implicit in the mainstream neoclassical DSGE models (productivity equals remuneration of factors of production), or for a natural rate for that matter. And that is the problem with Krugman and his New Keynesian friends, too much preoccupation with fashion, not enough with logic and evidence. If the profession remains concerned with fashionable models it will continue to be irrelevant and impractical.

Microfoundations and the capital debates

Steve has commented on the ongoing debates about microfoundations of macroeconomics, mainly between Paul Krugman and Simon Wren-Lewis (for my comments and Simon's reply on his blog go here, and scroll down to the last comments). I just want to further clarify what I think is, from the point of view of the history of ideas, a significant confusion in the debates about microfoundations, and one (oh yes, here he comes again) that is ultimately related to the capital debates (the Rosetta Stone of the history of economics ideas; if you prefer Sraffa's PCMC, as I tell my students, is the Rosetta Stone. To get an idea of what is the meaning of the capital debates go here).

Microfoundations are first and foremost about the determination of relative prices, the core of what we now call microeconomics, and used to be called before the theory of value. Individual behavior, rational or otherwise, is relevant to the extent that one thinks that behavior of individual agents is central for price determination, and that was at the core of the Marginalist Revolution.

The point is that if individual workers (using the figure of a representative rational utility maximizing worker), for example, in the labor market, confronts rational individual profit maximizing firms (again a representative firm), the free play of the market would produce an optimal outcome. Krugman is very clear why he thinks microfoundations are important. He says:

“if the assumption of perfect rationality breaks down even in the most standard of micro settings — if consumers behave in a way inconsistent with full maximization even when doing something as mundane as choosing which type of gas to put in their tank — how absurd is it to insist that, say, Keynesian stories about the economy can’t be right because we can’t fully derive them from intertemporal maximization?”

In other words, if workers say are not concerned with maximizing utility in terms of higher real wages, but in terms of relative wages, or if firms have limited knowledge about the workers willingness to work, and have an incentive to pay wages above the reservation wage (the one that compensates workers for the trouble with parting with leisure time), then the imperfection implies that the labor market will not clear and you might have unemployment. This is basically the efficiency wage story that New Keynesians use to justify unemployment (note that unemployment does result from real wages above the equilibrium level, and not from lack of demand as in Keynes).*

The capital debates show that even if you have workers trying to maximize utility in the normal fashion, and firms too have full information, that is, in the absence of any imperfection, there is no guarantee that lower real wages would imply more intensive use of the labor ‘factor.’ It is actually quite simple, if commodities are produced with commodities, then a reduction in wages also reduces the price of all goods, since they are produced with labor too, and there is a possibility that the fall in the price of commodities that do not use too much labor falls more than proportionally, so the increase in their demand does not lead to an increase in the hiring of new workers. Also, as wages are central for the consumer’s demand, the income effect of any reduction in wages would trump any (if it is positive) substitution effect. In other words, why would a firm hire more workers (even cheap ones) if nobody buys their products?

Further, PCMC does provide a sound way of determining relative prices. Long term normal prices are determined by the technical conditions of production, given one distributive variable (either real wages or interest, or if one prefers, for a given wage-profit frontier). It does take long term patterns of demand as given obviously, since producers would not supply, in the long term, goods and services for which there is no demand. The analysis of the determinants of effectual demand, the long term patterns of demand, are at a lower level of abstraction, and include all the institutional factors associated to fashion, conspicuous display of power, the effects of marketing, etc., that Veblen, Galbraith (father) and other institutionalist authors suggested were relevant.

Also, workers are rationally trying to obtain a fair wage, and to consume according to their tastes and the other social and institutional factors that determine their behavior. But those are taken as given for the determination of long run prices. And firms do maximize profits, and this implies that they add a mark up on their full costs. These models were developed by the authors of the Full Cost Pricing School, and the literature on barriers to entry, e.g. Sylos-Labini, Steindl and others, and the empirical evidence tends to be favorable.

In that sense, heterodox (classical-Keynesian, by which I mean Sraffa’s prices cum Keynes/Kalecki’s effective demand) does have a coherent determination of long run prices, based on rational behavior, as the foundation of the macroeconomic theory. Markets do not produce optimal outcomes and unemployment of productive resources is the normal, long run, position of the economy. In fact, the capital debates not only say that classical political economy (the surplus approach) provides sound microfoundations, but also that it is NOT possible to do so within the neoclassical/marginalist paradigm.***

* Interestingly enough Krugman’s argument for the current recession is not a rigidity in the labor market, but one in the money market, that is, a rate of interest that does not allow for investment at the level of full employment savings, the so-called Liquidity Trap.

** And yes there is empirical evidence in favor of this view, since there is no support for the effect of lower real wages and higher employment. Real wages tend to be pro-cyclical, go down in a recession, and up in the boom.

*** Arrow-Debreu also does not provide a way out of this conundrum.

PS: For the implications of Sraffa's contribution for Keynesian economics see this paper, and this post.

A Critique of the Lucas Critique

The blogosphere, it seems recently, has been particularly rich in blogoyakking (sp?) concerning microfoundations. Wren-Lewis, Noah Smith, Krugman, Rowe, Plosser, and others just in the week prior to this post.

And this has caused a persistent itch of mine to clamor for scratching. Here goes.

The Lucas critique is fairly widely acknowledged to have at least exacerbated the trend toward insisting on microfoundations in macro theory, and thus the rise of New Keynesian Dynamic Stochastic General Equilibrium models. You know, representative agents showing rational expectations over generations, and all such things, reacting to policy changes. Which individual behaviors we can, more or less simply, just add up in order to understand the effects on the macro economy.

For those needing a brief review on "the" critique, Wikipedia is actually not bad, which I summarize. Lucas said:

"Given that the structure of an econometric model consists of optimal decision rules of economic agents, and that optimal decision rules vary systematically with changes in the structure of series relevant to the decision maker, it follows that any change in policy will systematically alter the structure of econometric models."

This is from his 1976 paper.

And the Wiki article summarizes the implications:

"The Lucas critique suggests that if we want to predict the effect of a policy experiment, we should model the "deep parameters" (relating to preferences, technology and resource constraints) that govern individual behavior. We can then predict what individuals will do, taking into account the change in policy, and then aggregate the individual decisions to calculate the macroeconomic effects of the policy change."

Thus, Bortis-style classical-Keynesianism was pretty much denuded: at best macro policy is effectively toothless, since that pesky agent will simply react to neutralize the policy actions;  and/or react so that the empirical regularities we were observing and making policy on will change. So we need to focus on micro and get that "right," the best we can do. The domination of Methodological Individualism on economic practice was on the rise.

I think Lucas got part of the diagnosis correct: individuals do react to macro policy changes but only indirectly. And he got most of it wrong. For the most part individual behaviors do not  directly change the  structure of the time series, but it is the change in the structure of the time series that changes individual behavior. Aggregate demand falls due to some shock - asset deflation, price shocks, war, pestilence, loss of income due to technology or offshoring. Producers then decrease output, and fire their workers.

This shock mechanism does induce individually optimizing behavior on the part of the business owner, given that what he optimizes is his profit function into which his production output enters.

For the newly unemployed person, since s/he no longer has a source of income, one can stretch and say that reducing consumption is individually optimizing at least of negative deviations from the budget. Of course this mechanism has it's own brutal zero lower bound - subsistence.  And does nothing to maximize utility.

Notice, no macro policy change is required here to start a recession or the recent depression; all we need is a sufficient shock to the system to start the negative feedback cycles rolling along.

We classical-Keynesian macroeconomists characterize these mechanisms as showing the fallacy of composition; the canonical principles of economics example is the paradox of thrift. You cannot use added-up individually optimizing behaviors to determine what is going to happen to the macro economy.

The reason is clear: emergent properties at the macro level have a life of their own. And its is these emergent properties like recessions and unemployment that directly affect the behavior of the economic person. I take here the strong version of emergent: a property or behavior at the aggregate level which cannot be observed or predicted at the individual level.

We do have methods that attempt to model this: the Keynesian aggregate expenditure model, but that is static. Dynamic macro econometric models, but those are difficult, and maybe it was because of these difficulties that the Lucas critique was so successful in attacking them.

I propose two things to restore the dominating importance of emergent macro properties on economic behavior. One is a recommitment to econometric modelling. Ever increasing data and increasingly better tools will continually improve modelling and forecasting results.

The other is a methodology that is vastly underused in economics, but widely used in various other sciences: network system analysis based on the mathematical theory of graphs. These methods lets us directly measure and model emergent dynamic behaviors from groups, like the individuals in an economy. No added up methodological individualism required; no agent-based model needed. Observe, model, and predict directly at the macro level.

While I believe empirical models, properly done, are fundamental to understanding and policy, network models provide us with a dynamic theory, emergent macro behaviors, that  support our correct Keynesian beliefs that it is the macro foundations of micro behavior that matter, not the other Lucasian way around.

Heterodox and Mainstream Economics: The Great Confusion

Simon Wren-Lewis has a post on heterodox versus mainstream macroeconomics in which he seems surprised by what he calls the Great Divide between the two groups. He claims to be sympathetic to the heterodox project, at least along the lines of Steve Keen, but argues that the "rejectionist strategy is of course unlikely to win friends within the mainstream."

Wren-Lewis also suggests that a Minsky model developed by Keen (which according to Keen was rejected by several mainstream journals) is very similar to his ideas, but he fails to note that the Keen's model, as well as Minsky's theory, does not include a crucial characteristic of mainstream models, New Keynesian (NK), New Classical (NC), Real Business Cycle (RBC) and New Neoclassical Synthesis (NNS) alike, namely: Friedman's natural rate hypothesis.*

If you accept that cycles are just a shock (monetary or real) to an optimal trend and that the only thing that prevents the return of the economy to its optimal level is some sort of rigidity, then the obvious solution, at least in the long run, is to eliminate the rigidities. By the way, that is the reason why the NKs and NNSs authors end up believing in a confidence fairy, very much like NCs and RBCs authors. The NK and NNS fairy being about higher inflation expectations allowing for more investment demand, rather than directly about the less uncertainty allowing for more investment.

Wren-Lewis' confusion is to assume that the proximity of heterodox Keynesian groups and NKs like him on policy issues implies that on a deeper theoretical level there must be agreement too, and that this does not happen because of the sectarian nature of the heterodoxy.

Krugman's views, by the way, are very similar, in the sense that he seems to not quite understand why he is not seen as Keynesian by some heterodox economists. In a recent post, he argues that:

"Some devotees of Keynes claim that people like me aren’t really Keynesians – and while there are some serious grounds for the charge, part of the reason is precisely that we’ve treated Keynes as an inspiration to be modified in the face of evidence rather than as holy writ."

The confusion is incredible. Keynes himself accepted some neoclassical ideas that made his argument limited and heterodox authors actually have discarded a lot of Keynesian concepts (I myself believe that both the marginal efficiency of capital and liquidity preference are highly problematic, but that is material for other posts). The problem with Krugman is that he maintains (yes you guessed) the natural rate (a concept that a least Keynes wanted to drop from his theory), and suggests that unemployment and the recession are caused by the downward rigidity of the interest rate (a liquidity trap), propositions for which there is little evidence. Krugman is the one that treats neoclassical principles (the idea that a natural rate exists) as holy writ!

Both Krugman and Wren-Lewis seem to believe that economics (and science) is about convincing the others on a political level and are puzzled by the fact that heterodox do not fall in line with the NKs. That is why a less rejectionist, to use Wren-Lewis term, strategy is suggested (a similar view by Colander is criticized here). The problem is that evidence and logic (for the logical critique of the natural rate you must get the capital debates) suggest that the natural rate does not exist. Don't get me wrong, on political issues most heterodox authors are with Krugman, Wren-Lewis and company, against austerity, but science implies (as Krugman himself notes) adherence to facts.

So why don't NKs just renounce to the idea of a natural rate once and for all. For one they would make lots of friends within the heterodox community, which is way ahead in understanding the crisis (and foreseeing it too), and also would make their models more realistic.

* I have my own troubles with the kind of model presented in that paper by Keen, which are related to his profit driven investment function, but that is better discussed in another post.