توسعه اقتصادی و توزیع درآمد

The Kuznets’ U-shaped hypothesis, which postulates that income inequality first increases and then decreases during development, has been extensively tested and empirically confirmed. The reason that income inequality first rises and then falls during the development process, however, has not been adequately analyzed and explained.

We maintain that if one adopts the usual model of long-run economic growth, where potential GDP is the combined output of the traditional economy and a modern sector which is incubated by technological change, then corresponding to the growth of potential GDP there will be an asymmetric parabolic movement of inequality, as postulated by Kuznets more than a half of a century ago. We base this on cross-country empirical estimates of the Kuznets’ curve (Campano & Salvatore, 1988) and the dynamics of the Harris–Todaro model, as modified by Salvatore (1988) of labor movement from the traditional to the modern sector and the corresponding adjustment to wages as this transpires. Initially, inequality will be minimum, but as labor participation in the modern sector increases, the higher wages in that sector will tend to increase inequality. This will continue up to a point, but after enough of the labor force is incorporated in the modern sector the differences in wages will begin to diminish. However, if a new modern sector is introduced and potential GDP shifts to a new trajectory before the turning point is reached, then income inequality will continue to worsen between the two sectors. This in part depends upon a country's ability to introduce new technology and create demand for higher-level skills. As Conceição and Galbraith (2001, p. 140) point out, “ The perhaps surprising fact is that technology, which had been credited for driving growth and prosperity, came equally to be blamed for this observed increase in inequality in developed countries.”