Part 3: Declining Inequality

This is part three of three-part series. In part one of this series, I discussed different kinds of inequality and which ones we should be concerned about. In part two of this series, I discussed measuring inequality. You can find part two here.

There is a widespread but mistaken belief that the tremendous progress across a range of metrics has coincided with increasing global inequality, but in fact the data in the Inequality of Human Progress Index (IHPI) created by myself and Vincent Geloso unambiguously show a decline in global inequality. That’s true on a variety of metrics, including income inequality, education inequality, and most important, overall inequality. In fact, across all but two of the dimensions of inequality that we analyzed, the world has become more equal since 1990.

Worldwide equality has grown continuously since 1990 for life expectancy, internet access, and education. Equality of political liberty has similarly improved almost continuously since 1990, although there has been a slight and troubling downturn in recent years. That recent reversal does not cancel out the long‐​term trend of widening access to political liberty but is a reminder that progress is neither inevitable nor irreversible. Political freedom can be lost if not safeguarded. Globally, incomes became less equal until the mid‐​2000s, but income equality has improved considerably since then. As for adequate nutrition, the trend line has been erratic, with a turn toward greater inequality in the early- to mid‐​2000s. Yet the long‐​term trend has been one of appreciable gains in nutritional equality, as access to an adequate food supply becomes more common around the world.

What about the two exceptions? Two indicators in the index show trends toward more inequality: mortality resulting from outdoor air pollution and infant mortality. Regarding air pollution deaths, they may be a result of economic growth in progress. Economists talk about this with references to the environmental Kuznets curve (created by Simon Kuznets), which predicts that pollution rises along with economic growth until reaching a critical threshold beyond which pollution decreases. The growing disparity in outdoor air pollution deaths may indicate that some countries are in the midst of this transition. Those developing countries will almost certainly experience gains in environmental quality similar to those seen in today’s rich countries as they, too, grow richer.

Regarding infant mortality, it is important to remember that in absolute terms, infant mortality has fallen around the world. The growing inequality in infant mortality outcomes could be attributed to the fact that reductions in child mortality in high-income countries have outpaced those in low-income countries since 1990. While infant mortality has, again, decreased globally as more and more children survive past their first year of life, advancements since 1990 appear to have simply occurred relatively faster in high-income nations with access to cutting-edge medical technologies.

These exceptions are important but our most significant finding is that overall inequality is down. In fact, when compared with inequality trends in prior indexes of inequality, which surveyed fewer dimensions, the IHPI shows a far greater degree of improvement toward global equality. This result suggests that older indexes tended to underestimate how widespread progress has been, as well as the share of improvements in living standards that have gone to the poorest people in the world. Global equality has grown faster than many appreciate.

In Adam Smith’s day, for each very rich man, there were at least 500 poor ones. Inequality was extreme. The wealth explosion since then has made even ordinary people today rich beyond the wildest 18th century dreams. In the past few decades, the world has become better off, and those gains have been widely shared. Increasing public awareness of the global decline of inequality may bolster support for the systems of free enterprise and liberalized international trade that Smith advocated and that have brought absolute poverty to record lows and made humans across the globe more equal.