An Economist Answers Some of My Questions About “Capital in the 21st Century”

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On Thursday I posted a couple of very rudimentary comments regarding Thomas Piketty’s blockbuster new book, Capital in the 21st Century. I had questions about Piketty’s estimates of r (return on capital) and g (economic growth) in the past and—much more importantly—how they were likely to play out in the future. But all I had were amateur musings because I am, after all, only an amateur.

However, yesterday Brad DeLong tackled some of the questions I asked in a far more rigorous and disciplined way, teasing out a lot of unstated implications along the way—including the importance of various measures of r and how they relate to the probability of increasing future wealth concentration in the real world. It’s a long post, and complex in places, but highly recommended. If you’re willing to work your way through it, DeLong provides a framework for thinking about Piketty’s model that helps you start to make sense of both the book and its conclusions.

POSTSCRIPT: I’ve gotten a couple of questions about why I seem unduly skeptical, or even harsh, about Piketty’s book. It’s obviously a landmark work, I don’t really mean to be unfair. But it’s a book with innovative and untested ideas that has obvious appeal to anyone left of center, and I think this is precisely the time to avoid unquestioning hosannas. Affinity bias makes us all sympathetic to Piketty’s arguments, and that’s why we should instead question it carefully and thoroughly.

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FACT:

Mother Jones was founded as a nonprofit in 1976 because we knew corporations and the wealthy wouldn't fund the type of hard-hitting journalism we set out to do.

Today, reader support makes up about two-thirds of our budget, allows us to dig deep on stories that matter, and lets us keep our reporting free for everyone. If you value what you get from Mother Jones, please join us with a tax-deductible donation today so we can keep on doing the type of journalism 2020 demands.

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