Income inequality and economic incentives: Is there an equity–efficiency tradeoff?

What is the basis and direction of relationship between income inequality and economic growth? The equity versus efficiency dictum which predicts a positive relationship between inequality, capital formation, and real GDP growth—emphasizes the importance of economic incentives. Subsequently, this was challenged by the incomplete markets and political outcomes theories, because of increasing empirical evidence of an inverse relationship between income inequality and economic growth. In this paper, we offer a further explanation of the basis and nature of the inequality–capital–growth relationship which emphasizes the divergence between savings and investment. For the United States over the period 1970–2006, we have found no empirical evidence for the support of the equity versus efficiency hypothesis—that economic incentives are necessary for capital accumulation and growth. In fact, it was discovered that in most cases, inequality has had little or no impact on movements in the US capital stock, net investment, and consequently, economic growth. Another interesting finding of this study was that inequality exhibits hysteresis—implying that any positive shock, such as the dot-com boom, can lead to persistent and enduring increases in inequality.

► Shocks can lead to persistent and enduring changes in inequality.
► We found that inequality changes have had no influence on the US capital stock.
► Some inequality measures have had an inverse effect on capital productivity.
► No evidence for the hypothesis that economic incentives are vital for investment.