What Have We Learned from Summers and Piketty Ten Years On?

This article introduces a special issue of the Review of Political Economy that revisits, ten years on, the debates sparked by Lawrence Summers' revival of the Secular Stagnation hypothesis and Thomas Piketty's Capital in the Twenty-First Century. Summers' diagnosis of a negative natural rate of interest and chronically deficient demand, together with Piketty's claim that a rate of return on capital exceeding the growth rate drives rising inequality, reopened longstanding questions about the dynamics of capitalism, the causes of inequality and the scope for policy intervention. The contributions collected here reconstruct the intellectual roots of these ideas, test their empirical validity, and explore their theoretical foundations across a range of frameworks of different inspiration. The introduction closes by outlining open questions for future research.