The long and the short of income inequality

Ezra Klein made a splash a few days ago by arguing that Obama is wrong to call rising inequality the defining challenge of our time, asserting that jobs should take precedence: "Growth simply isn't producing enough jobs. This is a more severe and more urgent problem than inequality.

Today, Paul Krugman counters that inequality that the president was right -- first because stagnant incomes may have contributed to the debt crisis and are now depressing consumer demand, but more fundamentally, because the wealthiest have converted their disproportionate economic power into disproportionate political power, corrupting the country's ability to address its policy challenges.  The  the super-0rich, Krugman charges, triggered the financial meltdown by building a bipartisan consensus for financial regulation -- and have crippled the recovery by demanding austerity.

Klein's binary choice between addressing unemployment or austerity seems fundamentally mistaken to me, I would supplement Krugman's analysis with research by Peter Turchin (thanks, T. Greer), who has identified very long-term cycles of expanding and contracting inequality, and tied them chiefly to the supply of labor: