In the wake of the global financial crisis, a number of high profile economists have sought to revive Alvin Hansen’s Depression-era theory of “secular stagnation” to account for the stagnant tendencies in the American economy, citing Japan as a cautionary tale of combined demographic and economic decline. Following Hansen, it is argued that the long-term stagnation of the world economy can be attributed to a failure of the reproductive will, made manifest in declining birth rates and ageing populations. Although the causal connections between population and price trends are controversial even among mainstream demographers and economists, such arguments date back to the origins of political economy and appear to magically resurface with each major episode of crisis. If the crisis is inflationary, it tends to be ascribed to overpopulation; if it is deflationary, we find a corresponding concern with slowing birth rates. This article seeks to understand the durability of the demographic theory of crisis by examining the punitive and restorative work it performs in periods of capitalist restructuring.