Sonntag, 1. Juli 2012

Makro, Evidenz und (konservative) Politik

In den USA gibt es derzeit in den Blogs eine interessante Debatte darüber, ob es eine Asymmetrie zwischen konservativen und keynesianisch orientierten Ökonomen hinsichtlich ihrer Bereitschaft Modelle und Weltanschauung aufgrund von empirischer Evidenz anzupassen. Hier zwei Links zu P. Krugman und N. Smith.

Noah schreibt zu der Frage, ob die Entwicklung zum Mainstream und die hartnäckige Verteidigung dieser Position durch die Neoklassik auf politisches Sponsoring oder das Verhalten der ökonomischen Zunft selber zurückzuführen ist, Folgendes:
"[...] [C]onservatives do not fund the Nobel Prize committee. Rich donors did not pressure a bunch of Swedish guys into giving big gold medals to Edward Prescott and Robert Lucas, the fathers of neoclassical macro. Nor do shadowy conservative gazillionaires own the AER or the JPE or the QJE. Journal editors' arms are not being twisted into publishing models based on technology shocks.

Instead, I think what happened was that the neoclassical people made an argument that sounded convincing at the time (the 70s and 80s), and the field bought it. And the field bought it because there are just no agreed-upon ways to falsify or support macro theories with data. This is not to say there exist no such ways. Data was not kind to Prescott's 1982 RBC model. But that was not considered sufficient grounds for the profession to reject the RBC idea. Macro is just not a profession where people say things like "Hey, inflation goes down in most recessions, this RBC thing can't be right!" It's a profession where people say things like "RBC is telling an interesting story that doesn't seem to explain the Great Depression, but seems like it could explain the stagflation of the 70s, but more importantly it developed a methodology that we all now want to use (DSGE), so let's give it a Nobel Prize."

And that, I think, is the bigger problem. Macro doesn't just have a bunch of conservative people running around being conservative. It also has broken institutions. Without a firm commitment to rejecting wrong theories, and without agreed-upon standards for doing so, it's very hard to overcome the politics. Sure, you can get a gang of liberal-minded people together and try to push back against the conservatives, but in the end the best you can hope for is a bitterly divided profession, resulting in a massive loss of prestige in the eyes of microeconomists and of the educated public. Which is exactly what we have now. It's not liberals' fault, there's just not much they can do to fix the situation.

If the data does not speak, bad ideas will persist. And without the proper institutions, the data will not be allowed to speak."
Ich bin auch hin und wieder, um nicht zu sagen oft, darüber erstaunt, wie dominant Modelleleganz bzw. mathematische Handhabbarkeit gegenüber Realitätsnähe bzw. Anpassungsgüte an beobachtete Daten sind. Und wie lange an Modellen festgehalten wird, die über lange Zeit falsche Voraussagen getroffen haben ... denken wir nur an die nun schon seit 2009 herumgeisternden Warnungen vor enormer Inflation aufgrund der geldpolitischen Reaktionen auf die Krise.

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