While America’s corporate executives are his special bête noire, Mr. Piketty is also deeply troubled by the tens of millions of working people—a group he disparagingly calls “petits rentiers”—whose income puts them nowhere near the “one percent” but who still have savings, retirement accounts and other assets. That this very large demographic group will get larger, grow wealthier and pass on assets via inheritance is “a fairly disturbing form of inequality.” He laments that it is difficult to “correct” because it involves a broad segment of the population, not a small elite that is easily demonized.

So what is to be done? Mr. Piketty urges an 80% tax rate on incomes starting at “$500,000 or $1 million.” This is not to raise money for education or to increase unemployment benefits. Quite the contrary, he does not expect such a tax to bring in much revenue, because its purpose is simply “to put an end to such incomes.” It will also be necessary to impose a 50%-60% tax rate on incomes as low as $200,000 to develop “the meager US social state.” There must be an annual wealth tax as high as 10% on the largest fortunes and a one-time assessment as high as 20% on much lower levels of existing wealth. He breezily assures us that none of this would reduce economic growth, productivity, entrepreneurship or innovation.

Not that enhancing growth is much on Mr. Piketty’s mind, either as an economic matter or as a means to greater distributive justice.