There is also an internal dynamic to all of this, reflecting the rhythm of scholarly debates. In particular, Thomas Piketty’s surprise best-seller, “Capital in the Twenty-First Century,” has clearly caught the economics profession flat-footed, and it is only now starting to respond.

It’s not that the heart of the profession buys into Mr. Piketty’s specific theoretical framework — although there’s much greater sympathy for it among those on the left than on the right — but rather that it highlighted the fact that mainstream economics still lacks a compelling explanation for why inequality has risen so sharply. And while many remain suspicious of Mr. Piketty’s dire prognosis that inequality will continue to rise, the absence of a strong competing theory means that agnosticism remains the only alternative pose.

There’s a sense, too, that the United States economy is starting to return to normal, after a recession that was far too deep, and a recovery that has been troublingly slow. And so perhaps it is natural that as concerns about the economic cycle become less pressing that dismal scientists will shift their gaze from unemployment to inequality.