In 2010, the U.S. estate tax expired and executors of wealthy decedents were not required to file estate tax returns. In the absence of the estate tax, beneficiaries received assets with carryover rather than stepped-up basis. Unrealized capital gains accounted for 44 percent of the fair market value of non-cash assets in estates that chose the carryover basis regime, and an even higher percentage for some asset categories. Many of the largest gains were on assets that had been held for at least two decades.

This paper summarizes the book and assesses the reviews contained in the four contributed papers. Gregory Clark provides convincing arguments that extend the book's forecast that future technological change will be slower. Nicholas Crafts shows declining mortality and shorter work hours greatly increase welfare-augmented TFP growth during 1929-50. Benjamin Friedman points out that optimism about future technological change casts doubt on future employment growth, while technological pessimism implies employment optimism. Daron Acemoglu and co-authors emphasize the institutional environment that influences the timing and magnitude of innovation.