Reply to Alan Day Haight

摘要

Alan Day Haight is incorrect in understanding Piketty's paradox as a "dynamic version" of Keynes' paradox of thrift. Keynes' paradox of thrift deals with equilibrium conditions relating to the flows of savings and investment. In contrast, the capital output ratio central to Piketty's paradox deals with a stock (capital) relative to a flow (output). Balanced growth cannot be considered an "equilibrium" condition without specifying an adjustment mechanism whereby balanced growth is re-established when the capital-output ratio becomes unbalanced. As illustrated by the Harrod-Domar case this unbalancing can be particularly degenerative when idle capacity develops.