This is where things are breaking down — where things have actually, and fairly indisputably, gotten worse since the 1970s. Crime is better, lifespans are longer, our material conditions have greatly improved — yes, even among the lower middle class. What hasn’t improved is the sense that you can plan for a decent life filled with love and joy and friendship, then send your children on to a life at least as secure and well-provisioned as your own.

How much of that could be fixed by Piketty’s proposal to tax away some huge fraction of national income from rich people? Some, to be sure. But writing checks to the bottom 70 percent would not fix the social breakdown among those without a college diploma — the pattern of marital breakdown showed up early, and strong, among welfare mothers.

Writing checks to the bottom 70 percent would probably alleviate some of the worst stresses of being a single mother — but even in Scandinavia, the children of single parents still don’t do as well as children raised in intact households. Similarly, an unemployment check eases the financial stress of joblessness, but not the psychological pain of being out of work. To the extent that it helps people to stay on the dole and look for a perfect job that doesn’t exist, it may make people less happy, not more so.

Writing checks to the bottom 70 percent will not prevent a factory from moving to China or find meaningful replacement work for the 50-year-old accountant who has been there for 20 years.