Theoretical models and empirical studies exploring the relationship between income inequality and growth reach a disappointing inconclusive answer. We postulate in this paper that one reason for this inconclusive result is that income inequality consist at least in two different sorts of inequality, inequality of opportunity and effort. These two types of inequality would affect growth through opposite channels. As a result, the relationship between income inequality and growth could be positive or negative depending on which kind of inequality is more relevant. We test this proposal using depurated data of the PSID database for 24 US states from 1980 to 2000. We estimate regressions that relate growth with overall income inequality, inequality of opportunity and other widespread used control variables. We find robust support for a negative relationship between inequality of opportunity and growth and a positive relationship between growth and income inequality.JEL Classification: D63, H00.Key Words: income inequality; inequality of opportunity; economic growth.
INTRODUC TIONAn upsurge literature on income inequality and growth has emerged over the last two decades. The development of endogenous growth theory has provided the tools to handle the relationships between income inequality and economic growth within a dynamic equilibrium setting. Relaxing the representative-agent assumption raises two main questions. The first concerns the effects of income and wealth inequality on growth. The second addresses the reverse causation from growth to inequality, and disputes about the Kuznets (1955) hypothesis, according to which development and growth should eventually reduce income inequality.We concentrate on the first channel of influence, that is, on the effects of income inequality on growth. In this respect, two sets of growth models have been proposed in the literature: models where inequality is necessary for growth and models where inequality is harmful for growth. As it will become clear in the next section, the prevalence of a positive or negative relationship between income inequality and growth from a theoretical perspective is not possible since income inequality may affect economic growth in both directions through many different channels. For example, wealth and human capital heterogeneity across individuals produces a negative relationship between income inequality and growth because capital markets are imperfect. Meanwhile, income inequality may courage people s effort and, therefore, economic growth. In this manner, opposite forces give rise to a confusing picture of the relationship between economic growth and inequality. Worst still, the empirical evidence on the link from initial income inequality to future growth is mixed. Thus, there is a general inconclusiveness of cross-sectional and panel data studies of the relationship between income inequality and growth. In this respect, Ehrhart (2009) acknowledges in a recent survey on this topic that the overall rather disappointing econometric ...