Apunts de Macroeconomía Avançada II

Only insiders will know

Only insiders will know

 

ALERTA: Són apunts per a una assignatura de grau, no de Màster/Phd.

Resum: Aquest text consisteix en un recull d’apunts del material donat en l’assignatura Macroeconomia Avançada II, impartida per Jordi Galí a la Universitat Pompeu Fabra durant els curs acadèmics 2014-15 i 2015-16. En aquests apunts ens centrarem en la construcció i intuïció econòmica darrere dels models presentats en l’assignatura. L’estructura d’aquests apunts segueix la mateixa estructura que les diapositives facilitades per Jordi Galí, utilitzem material d’aquestes.

Fitxer: https://www.dropbox.com/s/24i2gd4d2nszwbi/MacroAdvIIApunts.pdf?dl=0

Disclaimer: Aquests apunts no són substitut per al material del professor i assistència a classe, estan incomplets (veure la part de mercat laboral del final…), a part de plens de faltes d’ortografia.

Vaig cursar aquesta assignatura ja farà temps i al coneixer de l’existència d’aquests apunts, he pensat que podrien ser útils a futurs estudiants.

La Ilusión Keynesiana

“A working macroeconomist reading Krugman and DeLong feels as a doctor would if the Surgeon General got up and said that the way to cure cancer was to draw blood using leeches.” DAVID K. LEVINE

There are no Phlogiston-theory chemists today. But we have DKL, who thinks that the right way to model business-cycle downturns is as the consequence of adverse supply shocks in the form of a decline in worker moral standards in a barter economy.WUSTL has a Phlogiston-theory economist. Today. Teaching.” BRADFORD DELONG

John Maynard Keynes

John Maynard Keynes

David K. Levine, economista, que tiene trabajos excelentes en contra de la propiedad intelectual con Michele Boldin (que ha traducido el escrito que comentaremos de Levine al italiano y que no es demasiado simpático hacia los keynesianos. Tuvo un debate con DeLong sobre la efectividad de los stimula fiscales y juntamente con Levine cargó contra Keynes en “All the interesting questions, almost all the wrong reasons”), ha cargado frontalmente contra la lógica keynesiana en su escrito “The Keynesian Illusion” que ha hecho hervir la sangre de más de uno, especialmente aquellos que utilizan modelos de la edad de piedra (IS-LM). Podemos encontrar diversas respuestas en la blogosfera económica, algunas más acertadas que otras: Bradford DeLong, Paul Krugman y Nick Rowe.

Primero, Levine explica la idea detrás del multiplicador y como una falta de demanda agregada genera desempleo involuntario:

I want to think here of a complete economy peopled by real people who produce and consume things. Let’s say four of them: a phone guy who makes phones, a burger flipper, a hairdresser and a tattoo artist. Let’s say that the burger flipper only wants a phone, the hairdresser only wants a burger, the tattoo artist only wants a haircut and the phone guy only wants a tattoo – around the circle in effect. We’ll suppose that each can produce one phone, burger, haircut or tattoo and that each values the unit of what they want to buy more than the unit of what they can sell. That is, the hairdresser happily cuts hair if he can get a burger and so forth. What happens is clear enough: the phone guy produces a phone, trades it to the tattoo artist in exchange for a tattoo, who trades the phone to the hairdresser in exchange for a haircut, who trades it to burger flipper in exchange for a burger. All are employed, all get what they want – everyone is happy. 

Now suppose that the phone guy suddenly decides he doesn’t like tattoos enough to be bothered building a phone. Now the circle is broken and this is a complete catastrophe. Everyone is unemployed. Demand is insufficient. There isn’t enough consumption – none at all in fact. And notice how this works: one person – the stupid phone guy who is causing the problem by not wanting to buy a tattoo – is “voluntarily unemployed” – he is lazy and doesn’t want to work. The other three are “involuntarily unemployed” each one is willing to work in exchange for pay. The burger flipper would like to work making burgers if he can get a phone, the hairdresser would like cut hair if he could get a burger and the tattoo artist would like to work if he could get a haircut and yet all are unemployed. DKL

Segundo, según Levine la idea del multiplicador vendría a ser que si el gobierno da un teléfono al productor de teléfonos, éste lo va a intercambiar por un tatuaje, el tatuador por un corte de pelo, etc. Y boom: “Full employment. Just put one phone and you also get a haircut, a tattoo and a burger!” El problema según Levine es de donde sale ese teléfono, si el gobierno tiene un teléfono para dar o no. Pues según Levine parece que no, si quita un teléfono a otro círculo para dárselo al del ejemplo, rompe otro círculo ya existente: “Let’s talk a bit more about how the government might get a phone – our poster child for anti-austerity at the moment is Greece. What if Germany gives a phone to Greece? That would be great – if the phone guy gets a phone, as we already know we are back to full employment – the multiplier and all that. But: what if Germany is just like Greece, except that their phone guy likes to make phones? If we take the phone away from the German phone guy then Germany collapses into unemployment – the multiplier works just as well in reverse.” DKL. Otra alternativa sería imprimir dinero y dárselo al productor de teléfonos para que este compre un tatuaje, el tatuador compre una hamburguesa, etc. pero una vez llegamos al burger flipper, este no puede comprar un teléfono ya que no hay teléfono. En este caso el burger flipper puede darse cuenta y directamente no vender la hamburguesa, con lo que tenemos otra vez el círculo roto, o no darse cuenta y vender la hamburguesa. El último caso Levine lo llama esquema Ponzi (a lo que es inflación no esperada) y a veces funciona, la gente se equivoca y el burger flipper ha sido “timado”, pero: you can’t fool... Por último, Levine comenta que siempre se puede obligar al productor de teléfonos a producir un teléfono, pero:

But then let’s at least not pretend that there is a free lunch – let’s be honest and say that we are screwing the phone guy to help everyone else. It doesn’t seem that this is what Keynes or the Keynesians are talking about – and forcing people to work against their will probably seems pretty fantastic as an economic policy…but let’s go back to the example of World War II because that is exactly what the government did – not only did they spend a lot of money that they borrowed or printed, but they also drafted soldiers into the military and forced a lot of businesses to produce and do things they would really rather not have done. And certainly while economic activity may have picked up a great deal during and after the war – it is doubtful that the draftees who died in the war benefited much from this. So the big evidence for Keynesianism fades away when we scrutinize it a bit more closely – and what did happen seems to accord pretty well with very simple and very classical economic theory. DKL

Y así es como Levine termina afirmando que: “So there you have it: if we take Keynes theory and measure the angles carefully we discover you can’t make a perpetual motion machine.” Cabe mencionar que el ejemplo de Levine incluye todos los elementos básicos de la narrativa keynesiana, en especial precios rígidos (todo es indivisible) en este caso estático.

La analogía de David K. Levine de la “Teoría General del Empleo, el Interés y el Dinero”

La analogía de David K. Levine de la “Teoría General del Empleo, el Interés y el Dinero”

Levine también comenta fallos de coordinación, algo que ya va más allá de cuestiones IS-LM, como que los agentes no estén seguros que el resto les vaya a aceptar el teléfono aún cuando el productor de teléfonos está dispuesto a producir uno, pero es difícil ver cómo el Estado dando un telèfono al productor de teléfonos o obligándole a producir uno soluciona el problema.

Cabe mencionar que la economía de DKL, no es una economía de trueque, el ejemplo está construido de forma que el trueque unilateral es imposible, el telèfono sirve como dinero en esta economía que DKL construye. Por esto, DeLong yerra al criticar que utiliza una economía de trueque como ejemplo. La idea subyacente del modelo de DKL es la de Kiyotaki-Wright (1989), dinero-mercancía, como bien menciona Williamson. Para una respuesta más completa de DKL a DeLong, ver el Addendum del texto de DKL. DKL comenta que aún añadiendo pagarés (IOU), el problema no desaparece:

We could, for example, have trade take place using IOUs rather than phones. So that the phone guy trades the tattoo artist an IOU for a phone in exchange for a tattoo, the tattoo artist trades the IOU for a haircut, the hairdresser trades the IOU for a burger, and then the burger flipper redeems the IOU in exchange for the phone. This is called inside money and as you can see nothing much changes – except that the role of trust is highlighted – each must trust the promise of the phone guy to give the phone in exchange for the IOU, and you can see how there can be coordination failure if trust fails – again without an obvious way in which government can restore this trust. DKL

Aquí es donde entraría la crítica de Rowe, donde al asumir que en el ejemplo inicial el teléfono actúa como dinero, el gobierno claro que tiene teléfonos de sobra para dar ya que el teléfono es dinero y el gobierno puede imprimir dinero. El gobierno es el productor de teléfonos (dinero)! De hecho, la narrativa de DKL se convierte en una explicación muy monetarista, una recesión causada por una política monetaria contraccionaria o no suficientemente expansiva (como argumentaría Scott Sumner de la Gran Recesión).

In this model economy, phones are used as the medium of exchange. And they need to use a medium of exchange because there’s a Wicksellian triangle (or quadrilateral in this case) with no double-coincidence of wants, so direct barter won’t work.

Now if this were my story, I would translate the metaphor by saying that phones are money, so the phone guy who makes phones is the central bank which makes money. And the stupid phone guy who creates the whole mess by not making enough phones is the stupid central bank which creates the whole mess by not making enough money. It’s a very monetarist story.

The phone guy is the government (or rather, the government-owned central bank). The phone is money. And so the phone guy/central bank does have phones/money to give away (or sell).     Nick Rowe

La analogía de David K. Levine para las políticas de stimula fiscales

La analogía de David K. Levine para las políticas de stimula fiscales

Esto ya pone en duda la tesis de Levine, parece que la política monetaria sí va a ser efectiva, aunque en su ejemplo los stimula fiscales siguen siendo no efectivos. Ahora bien, si cogemos el ejemplo de Levine con las IOU, la crítica de Rowe no parece tan evidente, por mucho dinero que pueda generar el Estado, no genera dinero-mercancía, al final, el burger flipper quiere una teléfono real (no dinero): “On the other hand, if the phone guy decides he doesn’t want to make phones, giving him a second dollar doesn’t seem to solve the problem – he could trade the extra dollar around the circle, but in the end he would have to exchange a phone for a dollar – which we just agreed he doesn’t want to do.” DKL. Pero veamos el caso en el que hay un problema similar al de Rowe aunque algo más refinado:

So let’s rerun DKL’s scenario, with one small change–adding money to the economy–that makes all the difference:

Suppose that the phone guy has a bunch of Mortgage-Backed Securities in her retirement portfolio, which suddenly crash in value with the financial crisis.

The phone guy looks at her zero-value retirement portfolio and sets to work building a phone–but decides to use her earnings not to get a tattoo but to hold them in the form of outside money: cash. Catastrophe. Everyone is unemployed…. The stupid phone guy who is causing the problem by not wanting to buy a tattoo but instead to accumulate financial assets–is ‘voluntarily unemployed’–finds that she cannot sell her phone because the tattoo artist cannot sell his services to the phone maker, and the hairdresser cannot sell her services to the tattoo artist, and the burger flipper cannot sell his services to hairdresser, and so the burger flipper cannot even buy the phone. Everyone is “involuntarily unemployed”. The burger flipper would like to work making burgers if he can get a phone, the hairdresser would like cut hair if he could get a burger and the tattoo artist would like to work if he could get a haircut and yet all are unemployed…

DeLong

Aquí, si el Banco central le da a la imprenta y aumenta los saldos de efectivo reales del productor de teléfonos, este vuelve a producir teléfonos y el círculo vuelve a funcionar, desaparece el desempleo involuntario. A lo que Levine contesta con un artículo suyo, pero primero, matizando que inicialmente usa dinero-mercancía ya que con IOU las cosas se complican, debemos introducir porqué la gente quiere tener dinero externo, etc. Supuestamente es para hacer compras en un futuro pero para esto debemos introducir un futuro que complica mucho las cosas.

So what happens if we go beyond the simple one period Keynesian framework? What if people hold outside money so that they can use it for future trades? What happens if over time people sometimes want to buy and sometimes want to sell – although they don’t always know in advance which – and they hold outside money for the times in the future they will want to buy without wanting to sell? Here is a quote from the introduction to a 1992 paper that studies such a model: “a trader may occasionally find himself in a position in which he wishes to buy from another trader who wishes to sell but does not have enough money on hand to make the purchase. An expansionary [monetary] policy that gives all traders equal amounts of currency effectively redistributes wealth from the relatively rich seller to the relatively poor buyer. This can make possible socially desirable trades that would not otherwise take place.” Now there are a lot of hypotheticals in that – but the authors of the paper worked out the details carefully with math and concluded that sometimes everybody is made better off by such a policy. Can we leap from this to the conclusion that Keynesianism is right and that just spending money without regard to where it comes from and who it goes to cures all economic ills? Should we conclude that we should go back to using simple IS-LM models for policy analysis? At least one of the authors evidentally does not think so – the quote is from a paper entitled “The Optimum Quantity of Money Revisited”  and the authors are Tim Kehoe, Mike Woodford and me.

Even when he is right, however, the extent to which everybody is made better off is quite small: the paper shows that for reasonable parameter values if inflation increases by 1% this is equivalent to increasing GDP by .004 percent.     DKL

Para un análisis más detallado sobre el tema monetario, ver Williamson.

Ahora, por último cabe considerar si Levine no hace trampa “modelando” un shock de oferta: “Now suppose that the phone guy suddenly decides he doesn’t like tattoos enough to be bothered building a phone. Now the circle is broken and this is a complete catastrophe. Everyone is unemployed. Demand is insufficient.” DKL. Que el productor de teléfonos sea un “vago” no parece ser una buena forma de criticar a los keynesianos: “DKL’s argument that Friedmanite-monetarist expansionary policies cannot cure a downturn is, I believe, correct–if the downturn is caused by a sudden outbreak of worker laziness, an adverse supply shock that reduces potential output.” DeLong. Pero como Williamson menciona simplemente podemos darle la vuelta a la tortilla: ““It generates unemployment by a drop in the supply of phones rather than an increase in demand for phones.” That’s easy to do, and a nicer example I think. Suppose the burger flipper has a demand shock – i.e. her utility from phones drops sufficiently that she won’t accept a phone in exchange for a burger. Then we get the same result. Everyone is unemployed.” Williamson. También podemos encontrar una explicación que creo satisfactoria por Boldrin en sus respuestas al primer comentario de la entrada (parte en italiano parte en inglés) del texto de Levine.

Al final, ¿qué podemos aprender de este intercambio, a parte de la mala leche y bilis de muchos de los involucrados? Pues algunas diferencias entre los Nuevos Clássicos y los Nuevos Keynesianos (también podríamos incluir a monetaristas de mercado) que muy bien señala Kim, Miseong en “A Short Comment on the Philosophical Clash Behind Classicals and Market Monetarists/New Keyneisans” fruto del debate que ha generado Levine.

Kim, comenta que es bien sabido que si las restricciones presupuestarias están en igualdad (=), que lo están dadas las preferencias de los agentes, en muchos modelos de equilibrio general se da la ley de Walras (aunque los bienes deben pertenecer a la categoría de deseables). La ley de Walras postula que el valor de mercado de toda la oferta en exceso debe ser igual al valor de mercado de la demanda en exceso. Sabemos que durante las recesiones hay bienes y servicios que no se venden. Durante una recesión (aunque no todas) vemos bienes que no se venden en el mercado. Utilizando el marco anterior,  podemos decir que durante una recesión o bien hay un exceso de oferta de bienes (menos no dinero) o una falta de demanda para estos. Por lo tanto, esto tiene que ir acompañado demanda en exceso de dinero ya que en las economías monetarias los bienes se compran y venden por dinero. Si no hay demanda en exceso de dinero, no hay demanda en exceso de bienes global (aún cuando pueda haber algunos bienes con exceso de oferta y otros con falta de demanda). La conclusión es que las estrategias para solucionar estos problemas pasan por proporcionar dinero (del que hay exceso de demanda) y activos seguros (si la demanda en exceso de dinero es a causa de falta de activos seguros o instrumentos para ahorrar).

Siendo razonable la explicación anterior, ¿que dicen los Nuevos Clásicos? Pues para estos, no es suficiente que haya un exceso de demanda de dinero, las políticas para evitar esto deben ser exitosas. Para esto último es necesario saber por qué hay esa demanda en exceso de dinero y modelar-lo.

If we think these people are important, then we ought to put them in the model, explaining who they are, what they want, and whether they also might want phones and tattoos, and so forth.

[…] At this point we really need to ask who is holding money and why – and if the government gives people money, to whom do they give it? Perhaps if the government gives everyone an extra dollar – and so prices double – the phone guy will decide on account of inflation that he really wants four dollars not two for his retirement? To make sense of this we need to understand why people are holding dollars in the first place – that is why in my simple example I used commodity money: with outside money people presumably hold it not because of the beauty of the artwork but to buy things with it in the future. DKL

Así, sabemos como reacciona la economía a las políticas propuestas. La ley de Walras garantiza que los valores totales del exceso de demanda será cero, pero si al inyectar dinero, altera los precios de alguna forma, las restricciones presupuestarias se ven modificadas. No hay garantía alguna que las acciones del Estado hagan que volvamos, de “desequilibrio”, otra vez en equilibrio. De forma que según Kim:

When classical writers present simple monetary models that has commodity money that can also be expanded into fiat money case to explain why simply-explained fiscal and monetary actions can save economies from recessions, what they really want to say is that economies have to be modelled fully to give any policy clues. Otherwise, policies devised will be wrong. When classical thinkers say that excess demand really lacks any meaning, this seems to be because in economic models, everyone has reasons, whether that be psychological inertia or “rational” reasons, to behave that way. In a way, market disequilibrium itself has no meanings for many classicals. The solution of a model is, whether market clearing or non-clearing, equilibrium, by definition. Thus there is not really a need to think about disequilibrium phenomena – only economic models matter. Thus difference does not really lie on whether one side seems to be completely fooled or whether one is buried under market clearing frameworks.

BIBLIOGRAFÍA

Cochrane, Levine on the Keynesian Illusion: http://johnhcochrane.blogspot.com.es/2015/03/levine-on-keynesian-illusion.html

Levine, The Keynesian Illusion: http://www.dklevine.com/general/illusion.5.htm

 Williamson, No One Expects the Spanish Inquistiion: More on D.K. Levile and J.M Keynes: http://newmonetarism.blogspot.com.es/2015/03/no-one-expects-spanish-inquisition-more.html

Rowe, David Levine’s Accidental Monetarism: http://worthwhile.typepad.com/worthwhile_canadian_initi/2015/03/david-levines-accidental-monetarism.html

Krugman, Economic Ignorance Blogging: http://krugman.blogs.nytimes.com/2015/03/16/economic-ignorance-blogging/

Bradford DeLong, Time for a Rant!: Why Oh Why Cannot We Have Better Economists: http://www.bradford-delong.com/2015/03/time-for-a-rant-why-oh-why-cannot-we-have-better-economists.html

Kim, Minseong. “A Short Comment on the Philosophical Clash Behind Classicals and Market Monetarists/New Keyneisans.” New Keyneisans (March 24, 2015) (2015).

Kiyotaki, Nobuhiro, and Randall Wright. “On money as a medium of exchange.”The Journal of Political Economy (1989): 927-954.

Boldrin, Michele, and David K. Levine. “All the interesting questions, almost all the wrong reasons.” Pecchi et Piga (2008) (2008): 161-178.