John H. Cochrane para responder a una crítica de Krugman:
“In economics, stimulus spending ran aground on Robert Barro’s Ricardian equivalence theorem. This theorem says that debt-financed spending can’t have any more effect than spending financed by raising taxes. People, seeing the higher future taxes that must pay off the debt, will simply save more. […] Is this theorem true? It’s a logical connection from a set of “if” to a set of “therefores.” Not even Paul can object to the connection.
Therefore, we have to examine the “ifs.” And those ifs are, as usual, obviously not true. For example, the theorem presumes lump-sum taxes, not proportional income taxes. […]
Economists have spent a generation tossing and turning the Ricardian equivalence theorem, and assessing the likely effects of fiscal stimulus in its light, generalizing the “ifs” and figuring out the likely “therefores.” […]
This is how real thinking about stimulus actually proceeds. […]
Math in economics serves to keep the logic straight, to make sure that the “then” really does follow the “if,” which it so frequently does not if you just write prose. The challenge is how hard it is to write down explicit artificial economies with these ingredients, actually solve them, in order to see what makes them tick.”
Therefore, we have to examine the “ifs.” And those ifs are, as usual, obviously not true. For example, the theorem presumes lump-sum taxes, not proportional income taxes. […]
Economists have spent a generation tossing and turning the Ricardian equivalence theorem, and assessing the likely effects of fiscal stimulus in its light, generalizing the “ifs” and figuring out the likely “therefores.” […]
This is how real thinking about stimulus actually proceeds. […]
Math in economics serves to keep the logic straight, to make sure that the “then” really does follow the “if,” which it so frequently does not if you just write prose. The challenge is how hard it is to write down explicit artificial economies with these ingredients, actually solve them, in order to see what makes them tick.”
http://ricardo.ecn.wfu.edu/~cottrell/ecn272/cochrane.pdf para responder a una crítica de Krugman: