Uncategorized

Sargent e a macroeconomia

A dica do Duke é ótima. Sargent entrevistado. Trechos:

Rolnick: OK, here goes. Examples of such criticisms are that modern macroeconomics makes too much use of sophisticated mathematics to model people and markets; that it incorrectly relies on the assumption that asset markets are efficient in the sense that asset prices aggregate information of all individuals; that the faith in good outcomes always emerging from competitive markets is misplaced; that the assumption of “rational expectations” is wrongheaded because it attributes too much knowledge and forecasting ability to people; that the modern macro mainstay “real business cycle model” is deficient because it ignores so many frictions and imperfections and is useless as a guide to policy for dealing with financial crises; that modern macroeconomics has either assumed away or shortchanged the analysis of unemployment; that the recent financial crisis took modern macro by surprise; and that macroeconomics should be based less on formal decision theory and more on the findings of “behavioral economics.” Shouldn’t these be taken seriously?

Sargent: Sorry, Art, but aside from the foolish and intellectually lazy remark about mathematics, all of the criticisms that you have listed reflect either woeful ignorance or intentional disregard for what much of modern macroeconomics is about and what it has accomplished. That said, it is true that modern macroeconomics uses mathematics and statistics to understand behavior in situations where there is uncertainty about how the future will unfold from the past. But a rule of thumb is that the more dynamic, uncertain and ambiguous is the economic environment that you seek to model, the more you are going to have to roll up your sleeves, and learn and use some math. That’s life.

(…)

Sargent: I have two responses to your citation of criticisms of “rational expectations.” First, note that rational expectations continues to be a workhorse assumption for policy analysis by macroeconomists of all political persuasions. To take one good example, in the spring of 2009, Joseph Stiglitz and Jeffrey Sachs independently wrote op-ed pieces incisively criticizing the Obama administration’s proposed PPIP (Public-Private Investment Program) for jump-starting private sector purchases of toxic assets.3 Both Stiglitz and Sachs executed a rational expectations calculation to compute the rewards to prospective buyers. Those calculations vividly showed that the administration’s proposal represented a large transfer of taxpayer funds to owners of toxic assets. That analysis threw a floodlight onto the PPIP that some of its authors did not welcome.

And second, economists have been working hard to refine rational expectations theory. For instance, macroeconomists have done creative work that modifies and extends rational expectations in ways that allow us to understand bubbles and crashes in terms of optimism and pessimism that emerge from small deviations from rational expectations. An influential example of such work is the 1978 QJE [Quarterly Journal of Economics] paper by Harrison and Kreps.4 You should also look at a fascinating paper that builds on Harrison and Kreps, written by José Scheinkman and Wei Xiong in the 2003 JPE.5 As I mentioned earlier, for policymakers to know whether and how they can moderate bubbles, we need to have well-confirmed quantitative versions of such models up and running. We don’t yet, but we are working on it.

Finalmente:

Rolnick: What about the most serious criticism—that the recent financial crisis caught modern macroeconomics by surprise?

Sargent: Art, it is just wrong to say that this financial crisis caught modern macroeconomists by surprise. That statement does a disservice to an important body of research to which responsible economists ought to be directing public attention. Researchers have systematically organized empirical evidence about past financial and exchange crises in the United States and abroad. Enlightened by those data, researchers have constructed first-rate dynamic models of the causes of financial crises and government policies that can arrest them or ignite them. The evidence and some of the models are well summarized and extended, for example, in Franklin Allen and Douglas Gale’s 2007 book Understanding Financial Crises. Please note that this work was available well before the U.S. financial crisis that began in 2007.

Tem muito mais lá. Realmente recomendo a leitura