(Sodobna) makroekonomija je bullshit

Huh, to bi lahko bil najkrajši povzetek novega članka Paula Romerja “The Trouble With Macroeconomics“. Romer (nekdanji učenec Roberta Lucasa in avtor znamenite teorije endogene rasti) je po lanskem Mathiness (kjer je Lucasa in naslednike obtožil, da z ekscesivno matematiko zavajajo in v matematiko ovijajo svoja ideološka prepričanja) spet udaril. In tokrat je udaril še bolj silovito. V preglednem članku o razvoju makroekonomije v zadnjih desetletjih je Lucasa in sopotnike ter naslednike obtožil neznanstvenega pristopa k raziskovanju.

Na kratko rečeno, povedal je, da modeli, ki so jih razvili, dejansko niso mikrofundirani (ne temeljijo na dejanskem obnašanju posameznikov) in da trpijo za nezmožnostjo identifikacije, pač pa identifikacijo preprosto predpostavljajo. Vzroke za fluktuacijo ključnih makro agregatov pripisujejo imaginarnim (izmišljenim) šokom (najljubši je eksogeni tehnološki šok) namesto realnim šokom (kot je denimo fluktuacija agregatnega povpraševanja ali ukrepi monetarne in fiskalne politike), nato pa vpliv teh imaginarnih šokov “dokazujejo” z bayesianskim pristopom k ocenjevanju. S čimer zgolj potrjujejo svoja apriorna prepričanja. Ti sodobni modeli, nastali po Lucasovi kritiki, niso nič boljši od keynesianskih makro modelov, ki so jih nadomestili.

Problem sodobne makroekonomije, ki trdi, da temelji na mikroekonomskem obnašanju posameznikov, je, prvič, da je dejansko v nasprotju s podatki o dejanskem mikroekonomskem obnašanju posameznikov, in drugič, da tudi makroekonomski modeli, konstruirani na tej osnovi, niso zmožni pojasnjevati dejanske gospodarske dinamike, kaj šele je napovedovati. Temelji teh modelov so gnili, zato so se tudi modeli pokazali kot popolnoma neuporabni v praksi.

Romer pravi, da celotna čreda makroekonomskih sledilcev Lucasa (ter Prescotta in Sargenta) ne uporablja znanstvenih metod, pač pa sledi vrhovni avtoriteti, čeprav slednjo realnost (podatki) demantirajo. Romer zato kliče k izgonu kulta osebnosti in povratku znanosti v makroekonomijo. Kliče k povratku k intuiciji in na podatkih osnovani makroekonomiji.

Spodaj je nekaj sklepnih odlomkov iz njegovega članka, ki kritizirajo neznanstveni pristop sodobne makroekonomije in kolaboracionizem večine makroekonomistov, ki raje dogmatsko verjamejo v kult osebnosti vodje tropa, kot da bi njegove trditve preverili. Vzrok je večinoma v preračunljivosti, sicer ne bi mogli objavljati oziroma bi bili akademsko mrtvi.

For more than three decades, macroeconomics has gone backwards. The treatment of identification now is no more credible than in the early 1970s but escapes challenge because it is so much more opaque. Macroeconomic theorists dismiss mere facts by feigning an obtuse ignorance about such simple assertions as “tight monetary policy can cause a recession.” Their models attribute fluctuations in aggregate variables to imaginary causal forces that are not influenced by the action that any person takes. A parallel with string theory from physics hints at a general failure mode of science that is triggered when respect for highly regarded leaders evolves into a deference to authority that displaces objective fact from its position as the ultimate determinant of scientific truth.

Some of the economists who agree about the state of macro in private conversations will not say so in public. This is consistent with the explanation based on different prices. Yet some of them also discourage me from disagreeing openly, which calls for some other explanation.

They may feel that they will pay a price too if they have to witness the unpleasant reaction that criticism of a revered leader provokes. There is no question that the emotions are intense. After I criticized a paper by Lucas, I had a chance encounter with someone who was so angry that at first he could not speak. Eventually, he told me, “You are killing Bob.” But my sense is that the problem goes even deeper that avoidance. Several economists I know seem to have assimilated a norm that the post-real macroeconomists actively promote – that it is an extremely serious violation of some honor code for anyone to criticize openly a revered authority figure – and that neither facts that are false, nor predictions that are wrong, nor models that make no sense matter enough to worry about.

A norm that places an authority above criticism helps people cooperate as members of a belief field that pursues political, moral, or religious objectives. As Jonathan Haidt (2012) observes, this type of norm had survival value because it helped members of one group mount a coordinated defense when they were attacked by another group. It is supported by two innate moral senses, one that encourages us to defer to authority, another which compels self-sacrifice to defend the purity of the sacred.

Science, and all the other research fields spawned by the enlightenment, survive by “turning the dial to zero” on these innate moral senses. Members cultivate the conviction that nothing is sacred and that authority should always be challenged. In this sense, Voltaire is more important to the intellectual foundation of the research fields of the enlightenment than Descartes or Newton.

By rejecting any reliance on central authority, the members of a research field can coordinate their independent efforts only by maintaining an unwavering commitment to the pursuit of truth, established imperfectly, via the rough consensus that emerges from many independent assessments of publicly disclosed facts and logic; assessments that are made by people who honor clearly stated disagreement, who accept their own fallibility, and relish the chance to subvert any claim of authority, not to mention any claim of infallibility.

Some economists counter my concerns by saying that post-real macroeconomics is a backwater that can safely be ignored; after all, “how many economists really believe that extremely tight monetary policy will have zero effect on real output?” To me, this reveals a disturbing blind spot. The trouble is not so much that macroeconomists say things that are inconsistent with the facts. The real trouble is that other economists do not care that the macroeconomists do not care about the facts. An indifferent tolerance of obvious error is even more corrosive to science than committed advocacy of error.

It is sad to recognize that economists who made such important scientific contributions in the early stages of their careers followed a trajectory that took them away from science. It is painful to say this so when they are people I know and like and when so many other people that I know and like idolize these leaders. But science and the spirit of the enlightenment are the most important human accomplishments. They matter more than the feelings of any of us.

You may not share my commitment to science, but ask yourself this: Would you want your child to be treated by a doctor who is more committed to his friend the anti-vaxer and his other friend the homeopath than to medical science? If not, why should you expect that people who want answers will keep paying attention to economists after they learn that we are more committed to friends than facts.

Many people seem to admire E. M. Forster’s assertion that his friends were more important to him than his country. To me it would have been more admirable if he had written, “If I have to choose between betraying science and betraying a friend, I hope I should have the guts to betray my friend.”

Vir: Paul Romer

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