If the heart of the problem is a rate of return on private assets that is too high, the better solution is to lower that rate of return. How? Raise minimum wages! That lowers the return on capital that relies on low-wage labor. Support unions! Tax corporate profits and personal capital gains, including dividends! Lower the interest rate actually required of businesses! Do this by creating new public and cooperative lenders to replace today’s zombie mega-banks. And if one is concerned about the monopoly rights granted by law and trade agreements to Big Pharma, Big Media, lawyers, doctors, and so forth, there is always the possibility (as Dean Baker reminds us) of introducing more competition.
Finally, there is the estate and gift tax—a jewel of the Progressive era. This Piketty rightly favors, but for the wrong reason. The main point of the estate tax is not to raise revenue, nor even to slow the creation of outsized fortunes per se; the tax does not interfere with creativity or creative destruction. The key point is to block the formation of dynasties. And the great virtue of this tax, as applied in the United States, is the culture of conspicuous philanthropy that it fosters, recycling big wealth to universities, hospitals, churches, theaters, libraries, museums, and small magazines.