In Poor Economics, Abhijit Banerjee and Esther Duflo eschew grand theorizing about poverty reduction in favor of an approach in which intelligently designed and tested small interventions, based on a scientific understanding of the lives of the poor, marginally improve their welfare. In so doing, they describe the findings from the recent large literature describing the behavior and institutions of the poor and the consequences of policy and experimental interventions targeted to poverty populations. In this review, I assess whether “thinking small” with its associated policy regime of transfers, subsidies, and nudges, is both a practical and effective policy prescription for “fighting” poverty and whether the set of studies that have focused on populations that have not escaped poverty has improved our fundamental understanding of both the consequences and causes of poverty.

The recent literature exploiting natural events as “natural experiment” instruments is reviewed to assess to what extent it has advanced empirical knowledge. A weakness of the studies that adopt this approach is that the necessary set of behavioral, market, and technological assumptions made by the authors in justifying their interpretations of the estimates is often absent. The methodology and findings from twenty studies are summarized and simple economic models are used to elucidate the implicit assumptions made by the authors and to demonstrate the sensitivity of the interpretations of the findings to the relaxation of some of these assumptions.