Great buzz in the blogosphere over Chris Giles’s attack on Thomas Piketty’s Capital in the 21st Century. Giles finds a few clear errors, although they don’t seem to matter much; more important, he questions some of the assumptions and imputations Piketty uses to deal with gaps in the data and the way he switches sources. Neil Irwin and Justin Wolfers have good discussions of the complaints; Piketty will have to answer these questions in detail, and we’ll see how well he does it.

But is it possible that Piketty’s whole thesis of rising wealth inequality is wrong? Giles argues that it is:

The exact level of European inequality in the last fifty years is impossible to determine, as it depends on the sources one uses. However, whichever level one picks, the lines in red in the graph show that – unlike what Prof. Piketty claims – wealth concentration among the richest people has been pretty stable for 50 years in both Europe and theUS. There is no obvious upward trend. The conclusions of Capital in the 21st century do not appear to be backed by the book’s own sources.

OK, that can’t be right — and the fact that Giles reaches that conclusion is a strong indicator that he himself is doing something wrong.

I don’t know the European evidence too well, but the notion of stable wealth concentration in the United States is at odds with many sources of evidence. Take, for example, the landmark CBO study on the distribution of income; it shows the distribution of income by type, and capital income has become much more concentrated over time:

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It’s just not plausible that this increase in the concentration of income from capital doesn’t reflect a more or less comparable increase in the concentration of capital itself.

Beyond that, we have, as Piketty stresses, evidence from Forbes-type surveys, which show soaring wealth at the very top. And we have other estimates of wealth concentration, like Saez-Zucman, that use completely different methods but point to the same conclusion.

And there’s also the economic story. In the United States, income inequality has soared since 1980 by any measure you use. Unless the affluent starting saving less than the working class, this rise in income disparity must have led to a rise in wealth disparity over time.

The point is that Giles is proving too much; if his attempted reworking of Piketty leads to the conclusion that nothing has happened to wealth inequality, what that really shows is that he’s doing something wrong.

None of this absolves Piketty from the need to respond to each of the individual questions. But anyone imagining that the whole notion of rising wealth inequality has been refuted is almost surely going to be disappointed.