Krugman vs. Krugman

27 March, 2015 at 09:26 | Posted in Economics | 2 Comments

Paul Krugman wonders why no one listens to academic economists …

Listening_TitleOne answer is that economists don’t listen to themselves. More precisely, liberal economists like Krugman who want the state to take a more active role in managing the economy, continue to teach an economic theory that has no place for activist policy.

Let me give a concrete example.

One of Krugman’s bugaboos is the persistence of claims that expansionary monetary policy must lead to higher inflation. Even after 5-plus years of ultra-loose policy with no rising inflation in sight, we keep hearing that since so “much money has been created…, there should already be considerable inflation” … As an empirical matter, of course, Krugman is right. But where could someone have gotten this idea that an increase in the money supply must always lead to higher inflation? Perhaps from an undergraduate economics class? Very possibly — if that class used Krugman’s textbook.

Here’s what Krugman’s International Economics says about money and inflation:

“A permanent increase in the money supply causes a proportional increase in the price level’s long-run value. … we should expect the data to show a clear-cut positive association between money supplies and price levels. If real-world data did not provide strong evidence that money supplies and price levels move together in the long run, the usefulness of the theory of money demand we have developed would be in severe doubt …

A permanent increase in the level of a country’s money supply ultimately results in a proportional rise in its price level but has no effect on the long-run values of the interest rate or real output.”

This last sentence is simply the claim that money is neutral in the long run, which Krugman continues to affirm on his blog …

You might think these claims about money and inflation are unfortunate oversights, or asides from the main argument. They are not. The assumption that prices must eventually change in proportion to the central bank-determined money supply is central to the book’s four chapters on macroeconomic policy in an open economy …

So these are not throwaway lines. The more thoroughly a student understands the discussion in Krugman’s textbook, the stronger should be their belief that sustained expansionary monetary policy must be inflationary. Because if it is not, Krugman gives you no tools whatsoever to think about policy …

Liberal Keynesian economists made a deal with the devil decades ago, when they conceded the theoretical high ground. Paul Krugman the textbook author says authoritatively that money is neutral in the long run and that a permanent increase in the money supply can only lead to inflation. Why shouldn’t people listen to him, and ignore Paul Krugman the blogger?

J. W. Mason/The Slack Wire

Recept mot krisen

27 March, 2015 at 09:21 | Posted in Economics | Leave a comment

krisrubbeDet första rådet vid en finansiell härdsmälta är att det finansiella systemet bör repareras omedelbart. Det är hjärtat i marknadsekonomin. En finanskris kan inte hävas förrän kreditgivningen åter fungerar. Andra stimulansåtgärder blir till föga hjälp så länge som bankerna är förlamade …

Det andra rådet säger att de så kallade automatiska stabilisatorerna i den offentliga sektorns budget bör få verka i största möjliga utsträckning. Vid varje kris skjuter budgetunderskottet av sig självt i höjden som följd av växande offentliga utgifter för högre arbetslöshet och sjunkande skatteintäkter när konsumtion och sysselsättning krymper …

Detta andra råd kan synas enkelt och självklart. Men ingen svensk finansminister har öppet och helhjärtat vågat anamma principen att lämna över budgetspakarna till den finanspolitiska autopiloten, minst av allt vid djup kris. Ofta har man gjort tvärtom: dragit i den budgetpolitiska nödbromsen och stramat åt – och därmed förvärrat det ekonomiska läget …

Vår finanskris i början av 1990-talet demonstrerade den kritiska dynamiken på ett slående sätt. Då utmålades de automatiskt växande budgetunderskotten som tecken på ansvarslös och slapp finanspolitik – inte som tecken på väl fungerande stötdämpare. Experter från IMF på besök i Stockholm bidrog till den felaktiga tolkningen genom att rekommendera finanspolitisk åtstramning mitt under brinnande kris.

Förhoppningsvis finns det en bättre förståelse i dag. Även IMF har svängt, ångrat sin budgetsyn från 1990-talet och går nu ut med det allmänna rådet att inte strama åt. Budgetunderskotten måste få växa raskt under de närmaste krisåren för att hålla världsekonomin – liksom vår ekonomi – på rätt köl.

Lars Jonung

Hoppas nu att ordföranden i Finanspolitiska rådet erinrar sig vad professorn skrev …

Postmodern pedagogik-mumbo-jumbo

26 March, 2015 at 18:47 | Posted in Theory of Science & Methodology | 1 Comment

Den antiintellektuella avgrunden är nära när den postmoderna sanningsrelativismen infekterar det offentliga samtalet på alla nivåer, inklusive den akademiska världen.

truth_exit_signI Sverige tycks den pedagogiska disciplinen vara värst smittad. En docent i pedagogik fick för några år sedan Skolverkets uppgift att skriva en rapport om fysikundervisningen i den svenska skolan, samt komma med förslag på hur den skulle attrahera fler flickor.

Ur rapporten:

”Föreställningen om det vetenskapliga tänkandets självklara överhöghet rimmar illa med jämställdhets- och demokratiidealen. […] Vissa sätt att tänka och resonera premieras mera än andra i naturvetenskapliga sammanhang. […] Om man inte uppmärksammar detta riskerar man att göra missvisande bedömningar. Till exempel genom att oreflekterat utgå från att ett vetenskapligt tänkande är mer rationellt och därför borde ersätta ett vardagstänkande” …

Pedagogen skriver vidare i rapporten: ”En genusmedveten och genuskänslig fysik förutsätter en relationell infallsvinkel på fysiken samt att en hel del av det traditionella vetenskapliga kunskapsinnehållet i fysiken plockas bort.”

Det vetenskapliga kunskapsinnehållet i fysiken ska alltså ”plockas bort” för att ”underlätta” för flickor. Inte nog med att detta är en förfärlig kunskapssyn, det är dessutom kränkande att betrakta flickor som oförmögna eller sämre på att ta till sig kunskap i fysik.

Författaren till rapporten heter Moira von Wright och är numera professor i pedagogik och rektor för Södertörns högskola. När nu en sådan kunskapsteoretisk grundsyn slagit rot i våra högre lärosäten har vi ett problem …

Martin Ingvar  Christer Sturmark  Åsa Wikforss

Efter att ha läst i ett av de senaste numren av Pedagogisk Forskning i Sverige (2-3 2014) — där författaren till artikeln “En pedagogisk relation mellan människa och häst. På väg mot en pedagogisk filosofisk utforskning av mellanrummet” ger följande intressanta “programförklaring” — är man dock föga förvånad över sakernas tillstånd inom svensk pedagogisk “vetenskap”:

Med en posthumanistisk ansats belyser och reflekterar jag över hur både människa och häst överskrider sina varanden och hur det öppnar upp ett mellanrum med dimensioner av subjektivitet, kroppslighet och ömsesidighet.

elite-daily-sleeping-studentOch så säger man att pedagogikämnet är i kris. Undrar varför …

Why Paul Krugman is no real Keynesian

26 March, 2015 at 11:03 | Posted in Economics | 4 Comments

Keynes’s insights have enormous practical importance, according to Lance Taylor and Duncan Foley [who jointly received the Leontief Prize for Advancing the Frontiers of Economic Thought at Tufts University’s Global Development and Environment Institute on Monday.]

But isn’t Keynes now mainstream? No, say Foley and Taylor. The mainstream still sees economies as inherently moving to an optimal equilibrium … It still says demand causes short-run fluctuations, but only supply factors, such as the capital stock and technology, can affect long-run growth.

EVEN PAUL KRUGMAN, a self-described Keynesian, Nobel laureate, and New York Times columnist, writes in the 2012 edition of his textbook: “In the long run the economy is self-correcting: shocks to aggregate demand affect aggregate output in the short run but not in the long run” …

KeynesUpsidedownKrugman does point to one exception: If interest rates are nearly zero, as during the financial crisis, markets lose restorative force. But, Taylor asks, what’s the logic?

Keynes saw capitalism’s general state as allowing almost arbitrary unemployment: hence his “General Theory.” Full employment was a lucky exception.

To Taylor, calling full employment the general state and allowing one unlucky exception turns Keynes upside down. And look where this confusion has brought us, he adds. Take the current eurozone disaster. For two decades, the European Union bureaucracy in Brussels, the German Council of Economic Experts, and a chorus of others, branded Germany, the “sick man of Europe,” as suffering from a sclerotic supply side: rigid labor unions, impediments to layoffs, a burdensome welfare state. But German labor costs to produce output sank steadily, and Germany generated huge trade surpluses — hardly signs of a sclerotic supply side. Yet growth has barely averaged 1 percent a year since 2000.

Jonathan Schlefer

I can’t but agree with Taylor and Foley here. To a large degree one does get the impression that Krugman thinks he is a Keynesian because he is a stout believer in John Hicks IS-LM interpretation of Keynes.

In a post on his blog, self-proclaimed “proud neoclassicist” Paul Krugman has argued that “Keynesian” macroeconomics more than anything else “made economics the model-oriented field it has become.” In Krugman’s eyes, Keynes was a “pretty klutzy modeler,” and it was only thanks to Samuelson’s famous 45-degree diagram and Hicks’s IS-LM that things got into place. Although admitting that economists have a tendency to use ”excessive math” and “equate hard math with quality” he still vehemently defends — and always have — the mathematization of economics:

I’ve seen quite a lot of what economics without math and models looks like — and it’s not good.

However, being a student of Hyman Minsky, yours truly very much doubt that IS-LM is an adequate reflection of the width and depth of Keynes’s insights on the workings of modern market economies.

Almost nothing in the post-General Theory writings of Keynes suggests him considering Hicks’s IS-LM anywhere near a faithful rendering of his thought. In Keynes’s canonical statement of the essence of his theory — in the famous 1937 Quarterly Journal of Economics article — there is nothing to even suggest that Keynes would have thought the existence of a Keynes-Hicks-IS-LM-theory anything but pure nonsense. John Hicks, the man who invented IS-LM in his 1937 Econometrica review of Keynes’ General Theory — “Mr. Keynes and the ‘Classics’. A Suggested Interpretation” — returned to it in an article in 1980 — “IS-LM: an explanation” — in Journal of Post Keynesian Economics. Self-critically he wrote that ”the only way in which IS-LM analysis usefully survives — as anything more than a classroom gadget, to be superseded, later on, by something better — is in application to a particular kind of causal analysis, where the use of equilibrium methods, even a drastic use of equilibrium methods, is not inappropriate.”

IS-LM is typically set in a current values numéraire framework that definitely downgrades the importance of expectations and uncertainty — and a fortiori gives too large a role for interests as ruling the roost when it comes to investments and liquidity preferences. Reducing uncertainty to risk — implicit in most analyses building on IS-LM models — is nothing but hand waving. According to Keynes we live in a world permeated by unmeasurable uncertainty — not quantifiable stochastic risk — which often forces us to make decisions based on anything but “rational expectations.” Keynes rather thinks that we base our expectations on the “confidence” or “weight” we put on different events and alternatives. To Keynes expectations are a question of weighing probabilities by “degrees of belief,” beliefs that often have preciously little to do with the kind of stochastic probabilistic calculations made by the rational agents as modeled by “modern” social sciences. And often we “simply do not know.”

IS-LM not only ignores genuine uncertainty, but also the essentially complex and cyclical character of economies and investment activities, speculation, endogenous money, labour market conditions, and the importance of income distribution. Most of the insights on dynamic coordination problems that made Keynes write General Theory are lost in the translation into the IS-LM framework.

Sure, “New Keynesian” economists like Krugman — and their forerunners, “Keynesian” economists like Paul Samuelson and (young) John Hicks — certainly have contributed to making economics more mathematical and “model-oriented.”

wrong-tool-by-jerome-awBut if these math-is-the-message-modelers aren’t able to show that the mechanisms or causes that they isolate and handle in their mathematically formalized macromodels are stable in the sense that they do not change when we “export” them to our “target systems,” these mathematical models do only hold under ceteris paribus conditions and are consequently of limited value to our understandings, explanations or predictions of real economic systems.

The kinds of laws and relations that “modern” economics has established, are laws and relations about mathematically formalized entities in models that presuppose causal mechanisms being atomistic and additive. When causal mechanisms operate in real world social target systems they only do it in ever-changing and unstable combinations where the whole is more than a mechanical sum of parts. If economic regularities obtain they do it (as a rule) only because we engineered them for that purpose. Outside man-made mathematical-statistical “nomological machines” they are rare, or even non-existant. Unfortunately that also makes most of contemporary mainstream neoclassical endeavours of mathematical economic modeling rather useless. And that also goes for Krugman.

In recent blogposts Paul Krugman has come back to his idea that it would be great if the Fed stimulated inflationary expectations so that investments would increase. I don’t have any problem with this idea per se, but I don’t think it’s of the stature that Krugman seems to think. But although I have written extensively on Knut Wicksell and consider him the greatest Swedish economist ever, I definitely – since Krugman portrays himself as “sorta-kinda Keynesian” – have to question his invocation of Knut Wicksell for his ideas on the “natural” rate of interest. Krugman writes (emphasis added):

Start with the very simplest view of how Fed policy affects the economy: the Fed sets short-term interest rates, and other things equal a lower rate leads to higher output; the “natural rate” of interest … is the rate at which output equals potential, that is, at which there are neither inflationary nor deflationary pressures …

What does this tell us? First of all, that there is nothing “artificial” or “unnatural” about low interest rates; they’re low because demand is low, and the Fed is responding appropriately. If anything, the “unnatural” situation is that rates are too high, because they’re constrained by the zero lower bound (rates can’t go below zero, except for some minor technical bobbles, because people can always just hold cash).

wicksell3Second, the Fed’s inability to get rates as low as they should be justifies a search for policies that can fill this policy gap. Fiscal stimulus is one such policy; unconventional monetary policies of various kinds are another. Actually, the natural policy — natural in a Wicksellian sense, and also the one that in terms of standard economics should produce the least distortion — would be a credible commitment to higher inflation.

Now consider what Keynes himself wrote in General Theory:

In my Treatise on Money I defined what purported to be a unique rate of interest, which I called the natural rate of interest¾namely, the rate of interest which, in the terminology of my Treatise, preserved equality between the rate of saving (as there defined) and the rate of investment. I believed this to be a development and clarification of Wicksell’s ‘natural rate of interest’, which was, according to him, the rate which would preserve the stability of some, not quite clearly specified, price-level.

I had, however, overlooked the fact that in any given society there is, on this definition, a different natural rate of interest for each hypothetical level of employment. And, similarly, for every rate of interest there is a level of employment for which that rate is the ‘natural’ rate, in the sense that the system will be in equilibrium with that rate of interest and that level of employment. Thus it was a mistake to speak of the natural rate of interest or to suggest that the above definition would yield a unique value for the rate of interest irrespective of the level of employment. I had not then understood that, in certain conditions, the system could be in equilibrium with less than full employment.

I am now no longer of the opinion that the [Wicksellian] concept of a ‘natural’ rate of interest, which previously seemed to me a most promising idea, has anything very useful or significant to contribute to our analysis. It is merely the rate of interest which will preserve the status quo; and, in general, we have no predominant interest in the status quo as such.

Paul Krugman has on his blog tried to explain why we should still use the neoclassical hobby horse Aggregate Supply-Aggregate Demand model:

So why do AS-AD? … We do want, somewhere along the way, to get across the notion of the self-correcting economy, the notion that in the long run, we may all be dead, but that we also have a tendency to return to full employment via price flexibility. Or to put it differently, you do want somehow to make clear the notion (which even fairly Keynesian guys like me share) that money is neutral in the long run.

Actually, this is the same unsubstantiated stuff you find in all of the “fairly Keynesian” Greg Mankiw’s textbooks.

Well, THIS “fairly Keynesian” guy is not impressed. And I doubt that Keynes himself would have been impressed by having his theory being characterized with catchwords like “tendency to return to full employment” and “money is neutral in the long run.”

As Taylor and Foley convincingly argue — Krugman is no real Keynesian.

Added GMT 1630: In case you still think that Keynes shared Krugman’s concern of getting across “the notion of the self-correcting economy, the notion that in the long run, we may all be dead, but that we also have a tendency to return to full employment via price flexibility” — well, have a look at this 1934 BBC radio address by Keynes, and you will certainly come to think differently [h/t Sandwichman].

Statistics and mathematics — of no avail in solving our disagreements

25 March, 2015 at 20:29 | Posted in Economics | 3 Comments

Statistical Science is not really very helpful for understanding or forecasting complex evolving self-healing organic ambiguous social systems – economies, in other words.

leamer1 zoomedA statistician may have done the programming, but when you press a button on a computer keyboard and ask the computer to find some good patterns, better get clear a sad fact: computers do not think. They do exactly what the programmer told them to do and nothing more. They look for the patterns that we tell them to look for, those and nothing more. When we turn to the computer for advice, we are only talking to ourselves …

Mathematical analysis works great to decide which horse wins, if we are completely confident which horses are in the race, but it breaks down when we are not sure. In experimental settings, the set of alternative models can often be well agreed on, but with nonexperimental economics data, the set of models is subject to enormous disagreements. You disagree with your model made yesterday, and I disagree with your model today. Mathematics does not help much resolve our internal intellectual disagreements.

Ed Leamer

När bot blir sot

25 March, 2015 at 20:04 | Posted in Economics, Politics & Society | Leave a comment

Starka offentliga finanser är en absolut förutsättning för tillväxt och fler jobb. Det inser man nu i Frankrike, Irland, Italien, Portugal, Spanien, Storbritannien och inte minst Grekland. Runtom i Europa väntar tuffa budgetsaneringsprogram. Det vet vi i Sverige efter de krisår vi gått igenom framför allt under 90-talet – eller borde veta. För oss socialdemokrater är det självklart: Sverige ska tillbaka till överskott …

2011-10-26-dumb_and_dumber-533x299Det Europa behöver är en ny och stram Stabilitets- och tillväxtpakt byggd på tydliga regler och sanktioner som tvingar Europas länder att sanera sina statsfinanser … Det måste finnas konsekvenser för medlemsländer som bryter mot pakten. Det bör övervägas om medlemsländer som bryter mot pakten ska få ta del av EU-medel …

För Sveriges del är det oerhört viktigt att euron blir framgångsrik. Det är viktigt för Europas ekonomiska framtid. Vi är fortfarande positiva till euron som politiskt projekt och är övertygade om att den kan bidra till handel, jobb och långsiktig tillväxt …

Europa behöver en ny och stram Stabilitets- och tillväxtpakt och fler ansvarstagande europeiska regeringar.

Mona Sahlin Thomas Östros

Grodors plums och ankors plask.

Herre du milde!

Har för mig att Östros fick ett nytt jobb också för ett par veckor sedan …

Money hoarding — an explanation of today’s low inflation

25 March, 2015 at 14:58 | Posted in Economics | 10 Comments

Based on the [quantity theory of money equation MV = PQ] holding the money velocity constant, if the money supply (M) increases at a faster rate than real economic output (Q), the price level (P) must increase to make up the difference. According to this view, inflation in the U.S. should have been about 31 percent per year between 2008 and 2013, when the money supply grew at an average pace of 33 percent per year and output grew at an average pace just below 2 percent. Why, then, has inflation remained persistently low (below 2 percent) during this period? …

During the first and second quarters of 2014, the velocity of the monetary base2 was at 4.4, its slowest pace on record. This means that every dollar in the monetary base was spent only 4.4 times in the economy during the past year, down from 17.2 just prior to the recession. This implies that the unprecedented monetary base increase driven by the Fed’s large money injections through its large-scale asset purchase programs has failed to cause at least a one-for-one proportional increase in nominal GDP. Thus, it is precisely the sharp decline in velocity that has offset the sharp increase in money supply, leading to the almost no change in nominal GDP (either P or Q).

5267109005_ac183b2699So why did the monetary base increase not cause a proportionate increase in either the general price level or GDP? The answer lies in the private sector’s dramatic increase in their willingness to hoard money instead of spend it. Such an unprecedented increase in money demand has slowed down the velocity of Money …

And why then would people suddenly decide to hoard money instead of spend it? A possible answer lies in the combination of two issues:
•A glooming economy after the financial crisis
•The dramatic decrease in interest rates that has forced investors to readjust their portfolios toward liquid money and away from interest-bearing assets such as government bonds.

Yi Wen & Maria Arias (St. Louis Fed)

Anyone still believing in Say’s Law? Just wondering …

Macroeconomics — totally messed-up

25 March, 2015 at 09:12 | Posted in Economics | 1 Comment

Until a few years ago, economists of all persuasions confidently proclaimed that the Great Depression would never recur. In a way, they were right. After the financial crisis of 2008 erupted, we got the Great Recession instead. Governments managed to limit the damage by pumping huge amounts of money into the global economy and slashing interest rates to near zero. But, having cut off the downward slide of 2008-2009, they ran out of intellectual and political ammunition.

EconomistsMessedUp2

Economic advisers assured their bosses that recovery would be rapid. And there was some revival; but then it stalled in 2010. Meanwhile, governments were running large deficits – a legacy of the economic downturn – which renewed growth was supposed to shrink. In the eurozone, countries like Greece faced sovereign-debt crises as bank bailouts turned private debt into public debt.

Attention switched to the problem of fiscal deficits and the relationship between deficits and economic growth. Should governments deliberately expand their deficits to offset the fall in household and investment demand? Or should they try to cut public spending in order to free up money for private spending?

Depending on which macroeconomic theory one held, both could be presented as pro-growth policies. The first might cause the economy to expand, because the government was increasing public spending; the second, because they were cutting it. Keynesian theory suggests the first; governments unanimously put their faith in the second.

The consequences of this choice are clear. It is now pretty much agreed that fiscal tightening has cost developed economies 5-10 percentage points of GDP growth since 2010. All of that output and income has been permanently lost. Moreover, because fiscal austerity stifled economic growth, it made the task of reducing budget deficits and national debt as a share of GDP much more difficult. Cutting public spending, it turned out, was not the same as cutting the deficit, because it cut the economy at the same time.

Robert Skidelsky

Boom Bust Boom

24 March, 2015 at 16:54 | Posted in Economics | Leave a comment

 

On the value of theoretical models in economics

23 March, 2015 at 17:22 | Posted in Theory of Science & Methodology | 1 Comment

Chameleons arise and are often nurtured by the following dynamic. First a bookshelf model is constructed that involves terms and elements that seem to have some relation to the real world and assumptions that are not so unrealistic that they would be dismissed out of hand. monocle_chameleon_2The intention of the author, let’s call him or her “Q,” in developing the model may be to say something about the real world or the goal may simply be to explore the implications of making a certain set of assumptions. Once Q’s model and results become known, references are made to it, with statements such as “Q shows that X.” This should be taken as short-hand way of saying “Q shows that under a certain set of assumptions it follows (deductively) that X,” but some people start taking X as a plausible statement about the real world. If someone skeptical about X challenges the assumptions made by Q, some will say that a model shouldn’t be judged by the realism of its assumptions, since all models have assumptions that are unrealistic …

Chameleons are models that are offered up as saying something significant about the real world even though they do not pass through the filter. When the assumptions of a chameleon are challenged, various defenses are made (e.g., one shouldn’t judge a model by its assumptions, any model has equal standing with all other models until the proper empirical tests have been run, etc.). In many cases the chameleon will change colors as necessary, taking on the colors of a bookshelf model when challenged, but reverting back to the colors of a model that claims to apply the real world when not challenged.

Paul Pfleiderer

Reading Pfleiderer’s article reminds me of what H. L. Mencken once famously said:

There is always an easy solution to every problem – neat, plausible and wrong.

Pfleiderer’s perspective may be applied to many of the issues involved when modeling complex and dynamic economic phenomena. Let me take just one example — simplicity.

When it come to modeling I do see the point emphatically made time after time by e. g. Paul Krugman in simplicity — as long as it doesn’t impinge on our truth-seeking. “Simple” macroeconomic models may of course be an informative heuristic tool for research. But if practitioners of modern macroeconomics do not investigate and make an effort of providing a justification for the credibility of the simplicity-assumptions on which they erect their building, it will not fulfill its tasks. Maintaining that economics is a science in the “true knowledge” business, I remain a skeptic of the pretences and aspirations of  “simple” macroeconomic models and theories. So far, I can’t really see that e. g. “simple” microfounded models have yielded very much in terms of realistic and relevant economic knowledge.

All empirical sciences use simplifying or unrealistic assumptions in their modeling activities. That is not the issue – as long as the assumptions made are not unrealistic in the wrong way or for the wrong reasons.

But models do not only face theory. They also have to look to the world. Being able to model a “credible world,” a world that somehow could be considered real or similar to the real world, is not the same as investigating the real world. Even though — as Pfleiderer acknowledges — all theories are false, since they simplify, they may still possibly serve our pursuit of truth. But then they cannot be unrealistic or false in any way. The falsehood or unrealisticness has to be qualified.

Explanation, understanding and prediction of real world phenomena, relations and mechanisms therefore cannot be grounded on simpliciter assuming simplicity. If we cannot show that the mechanisms or causes we isolate and handle in our models are stable, in the sense that what when we export them from are models to our target systems they do not change from one situation to another, then they – considered “simple” or not – only hold under ceteris paribus conditions and a fortiori are of limited value for our understanding, explanation and prediction of our real world target system.

The obvious ontological shortcoming of a basically epistemic – rather than ontological – approach, is that “similarity” or “resemblance” tout court do not guarantee that the correspondence between model and target is interesting, relevant, revealing or somehow adequate in terms of mechanisms, causal powers, capacities or tendencies. No matter how many convoluted refinements of concepts made in the model, if the simplifications made do not result in models similar to reality in the appropriate respects (such as structure, isomorphism etc), the surrogate system becomes a substitute system that does not bridge to the world but rather misses its target.

Constructing simple macroeconomic models somehow seen as “successively approximating” macroeconomic reality, is a rather unimpressive attempt at legitimizing using fictitious idealizations for reasons more to do with model tractability than with a genuine interest of understanding and explaining features of real economies. Many of the model assumptions standardly made by neoclassical macroeconomics – simplicity being one of them – are restrictive rather than harmless and could a fortiori anyway not in any sensible meaning be considered approximations at all.

If economists aren’t able to show that the mechanisms or causes that they isolate and handle in their “simple” models are stable in the sense that they do not change when exported to their “target systems”, they do only hold under ceteris paribus conditions and are a fortiori of limited value to our understanding, explanations or predictions of real economic systems.

That Newton’s theory in most regards is simpler than Einstein’s is of no avail. Today Einstein has replaced Newton. The ultimate arbiter of the scientific value of models cannot be simplicity.

As scientists we have to get our priorities right. Ontological under-labouring has to precede epistemology.

 

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