Montag, 19. Mai 2014

Und noch mehr über Piketty

Der Hype geht weiter ...

Das Handelblatt berichtet lang und breit über den Weg "vom Ökonom zum Superstar".

Wirklich lesenswert ist eine Rezession des Buchs von Piketty von L. Summers. Dieser lobt das Buch als wichtigen Beitrag, vor allem durch die Dokumentierung empirischer Fakten. Er ist jedoch sehr skeptisch bezüglich der Erklärungen, die Piketty anbietet.
"Piketty’s timing may be impeccable, and his easily understandable but slightly exotic accent perfectly suited to today’s media; but make no mistake, his work richly deserves all the attention it is receiving. This is not to say, however, that all of its conclusions will stand up to scholarly criticism from his fellow economists in the short run or to the test of history in the long run. Nor is it to suggest that his policy recommendations are either realistic or close to complete as a menu for addressing inequality.

Start with its strengths. In many respects, Capital in the Twenty-First Century embodies the virtues that we all would like to see but find too infrequently in the work of academic economists. It is deeply grounded in painstaking empirical research. Piketty, in collaboration with others, has spent more than a decade mining huge quantities of data spanning centuries and many countries to document, absolutely conclusively, that the share of income and wealth going to those at the very top—the top 1 percent, .1 percent, and .01 percent of the population—has risen sharply over the last generation, marking a return to a pattern that prevailed before World War I. There can now be no doubt that the phenomenon of inequality is not dominantly about the inadequacy of the skills of lagging workers. Even in terms of income ratios, the gaps that have opened up between, say, the top .1 percent and the remainder of the top 10 percent are far larger than those that have opened up between the top 10 percent and average income earners. Even if none of Piketty's theories stands up, the establishment of this fact has transformed political discourse and is a Nobel Prize-worthy contribution. [...]

There is also the question of whether the returns to wealth are largely reinvested. A central claim by Piketty is that a country’s wealth-income ratio tends toward s/g, the ratio of its savings rate to its growth rate. Hence, as he argues, a declining growth rate leads to a higher wealth ratio. But this presumes a constant or rising saving ratio. Since he imagines returns to capital as largely reinvested, he finds this a plausible assumption.

I am much less sure. At the simplest level, consider a family with current income of 100 and wealth of 100 as opposed to a family with current income of 100 and wealth of 500. One would expect the former family to have a considerably higher saving ratio. In other words, there is a self-correcting tendency Piketty abstracts from whereby rising wealth leads to declining saving. 

The largest single component of capital in the United States is owner-occupied housing. Its return comes in the form of the services enjoyed by the owners—what economists call “imputed rent”—which are all consumed rather than reinvested since they do not take a financial form. The phenomenon is broader. The determinants of levels of consumer spending have been much studied by macroeconomists. The general conclusion of the research is that an increase of $1 in wealth leads to an additional $.05 in spending. This is just enough to offset the accumulation of returns that is central to Piketty’s analysis."

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