But why does this growing concentration of income and wealth in a few hands matter? Part of the answer is that rising inequality has meant a nation in which most families don’t share fully in economic growth. Another part of the answer is that once you realize just how much richer the rich have become, the argument that higher taxes on high incomes should be part of any long-run budget deal becomes a lot more compelling.

The larger answer, however, is that extreme concentration of income is incompatible with real democracy. Can anyone seriously deny that our political system is being warped by the influence of big money, and that the warping is getting worse as the wealth of a few grows ever larger?

Some pundits are still trying to dismiss concerns about rising inequality as somehow foolish. But the truth is that the whole nature of our society is at stake.