Theories of fertility decline and the evidence from development indicators

Most social scientists agree that socioeconomic change and the diffusion of new ideas have both contributed to fertility declines in developing countries. Disagreement remains, however, over the relative importance of the two sets of causes. Assessments of the relative importance typically use data on the relationship between fertility and development indicators such as GDP per capita and literacy. The prevailing interpretation of this evidence is that it demonstrates major weaknesses in socioeconomic explanations. Three propositions have become widely accepted: (1) fertility declines in countries with low scores on development indicators cannot be explained by socioeconomic theories; (2) the relationship between fertility and development is weaker than would be predicted by socioeconomic theories; and (3) the relationship between development and fertility has shifted over time. This article questions the accuracy and substantive significance of all three propositions. It argues that fertility declines in at least some countries with low development scores can be reconciled with some socioeconomic theories. It shows that a handful of development indicators can predict most of the important characteristics of fertility declines in a sample of 87 developing countries. It then shows that previous analyses have overestimated the size of shifts in the relationship between fertility and development. The conclusion is that socioeconomic theories of fertility decline fit the evidence better than is generally thought.