Efforts to construct large-scale economic models have been singularly unproductive to date. To put it even more strongly, I cannot think of an important economic insight that has come out of such models. In fact, they have often led us astray.
Si lo pensamos bien, es absurdo y pueril enfrentar escuelas de economía (Como lo es enfrentar ideologías excluyentes). Rodrik dice que los modelos son como fábulas, o parábolas, que simplifican y eliminan elementos superfluos para explicar la realidad. Cada una de ellas tiene un mensaje - ahorrar es bueno, trabajar también, lo importante es la confianza en uno mismo, dad y se os dará, etc- pero es obvio que son mensajes incompatibles, lo no los hace falsos. ¿Ahorrar es bueno pero dar a los demás también? Simplemente, son verdades contingentes. El problema es saber cuando son superfluos o relevantes los elementos eliminados: depende.Overconfidence in the prevailing macroeconomic orthodoxy of the day resulted in the construction of several large-scale simulation models of the US economy in the 1960s and 1970s built on Keynesian foundations. These models performed rather badly in the stagflationary environment of the late 1970s and 1980s. They were subsequently jettisoned in favor of “new classical” approaches with rational expectations and price flexibility. Instead of relying on such models, it would have been far better to carry several small models in our heads simultaneously, of both Keynesian and new classical varieties, and know when to switch from one to the other.Without these smaller, more transparent models, large-scale computational models are, in fact, unintelligible. I mean this in two senses. First, the assumptions and behavioral relations that are built into the large models must come from somewhere. Depending on whether you believe in the Keynesian model or the new classical model, you will develop a different large-scale model... Second, and alternatively, suppose we can build large-scale models relatively theory-free, using big-data techniques based on observed empirical regularities such as consumer spending patterns. Such models can deliver predictions, like weather models do, but never knowledge on their own. For they are like a black box: we can see what is coming out, but not the operative mechanism inside.
En Economía pasa lo mismo. La realidad es demasiado compleja para explicarla con un solo modelo.
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