N. Gregory Mankiw: Is Government Spending Too Easy an Answer?





[N. Gregory Mankiw is a professor of economics at Harvard. He was an adviser to President Bush.]

... Economics textbooks, including Mr. Samuelson’s and my own more recent contribution, teach that each dollar of government spending can increase the nation’s gross domestic product by more than a dollar. When higher government spending increases G.D.P., consumers respond to the extra income they earn by spending more themselves. Higher consumer spending expands aggregate demand further, raising the G.D.P. yet again. And so on. This positive feedback loop is called the multiplier effect.

In practice, however, the multiplier for government spending is not very large. The best evidence comes from a recent study by Valerie A. Ramey, an economist at the University of California, San Diego. Based on the United States’ historical record, Professor Ramey estimates that each dollar of government spending increases the G.D.P. by only 1.4 dollars. So, by doing the math, we find that when the G.D.P. expands, less than a third of the increase takes the form of private consumption and investment. Most is for what the government has ordered, which raises the next question....

MIGHT TAX CUTS BE MORE POTENT? Textbook Keynesian theory says that tax cuts are less potent than spending increases for stimulating an economy. When the government spends a dollar, the dollar is spent. When the government gives a household a dollar back in taxes, the dollar might be saved, which does not add to aggregate demand.

The evidence, however, is hard to square with the theory. A recent study by Christina D. Romer and David H. Romer, then economists at the University of California, Berkeley, finds that a dollar of tax cuts raises the G.D.P. by about $3. According to the Romers, the multiplier for tax cuts is more than twice what Professor Ramey finds for spending increases.

Why this is so remains a puzzle. One can easily conjecture about what the textbook theory leaves out, but it will take more research to sort things out. And whether these results based on historical data apply to our current extraordinary circumstances is open to debate.

Christina Romer, incidentally, has been chosen as the chairwoman of the Council of Economic Advisers in the new administration. Perhaps this fact helps explain why, according to recent reports, tax cuts will be a larger piece of the Obama recovery plan than was previously expected....

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