Leading economists from Paul Samuelson to Paul Krugman have labored to allay the fear that technological advances may reduce overall employment, causing mass unemployment as workers are displaced by machines. This ‘lump of labor fallacy’—positing that there is a fixed amount of work to be done so that increased labor productivity reduces employment —is intuitively appealing and demonstrably false. Technological improvements create new products and services, shifting workers from older to newer activities. Higher productivity raises incomes, increasing demand for labor throughout the economy. Hence, in the long run technological progress affects the composition of jobs not the number of jobs.
First of all, Samuelson and Krugman didn't "labor to allay the fear." They spouted canned nonsense that was disavowed by "leading economists" nearly a century ago. Back in May I wrote Professor Krugman an open letter (hard copy sent by mail) detailing the discrepancies in the lump of labor fallacy claim and asking him to at least respond to the evidence I presented. Krugman did not reply.
I will, of course, forward copies of that open letter to Professors Autor and Katz -- with no great expectations.