Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

The statistician Ola Rosling (Hans’s son) has displayed the worldwide distribution of income as histograms, in which the height of the curve indicates the proportion of people at a given income level, for three historical periods (figure 8-3).¹⁹ In 1800, at the dawn of the Industrial Revolution, most people everywhere were poor. The average income was equivalent to that in the poorest countries in Africa today (about $500 a year in international dollars), and almost 95 percent of the world lived in what counts today as “extreme poverty” (less than $1.90 a day). By 1975, Europe and its offshoots had completed the Great Escape, leaving the rest of the world behind, with one-tenth their income, in the lower hump of a camel-shaped curve.²⁰ In the 21st century the camel has become a dromedary, with a single hump shifted to the right and a much lower tail on the left: the world had become richer and more equal.²¹

The slices to the left of the dotted line deserve their own picture. Figure 8-4 shows the percentage of the world’s population that lives in “extreme poverty.” Admittedly, any cutoff for that condition must be arbitrary, but the United Nations and the World Bank do their best by combining the national poverty lines from a sample of developing countries, which are in turn based on the income of a typical family that manages to feed itself. In 1996 it was the alliterative “a dollar a day” per person; currently it’s set at $1.90 a day in 2011 international dollars.²² (Curves with more generous cutoffs are higher and shallower but also skitter downward.)²³ Notice not just the shape of the curve but how low it has sunk—to 10 percent. In two hundred years the rate of extreme poverty in the world has tanked from 90 percent to 10, with almost half that decline occurring in the last thirty-five years.

Figure 8-4: Extreme poverty (proportion), 1820–2015

Sources: Our World in Data, Roser & Ortiz-Ospina 2017, based on data from Bourguignon & Morrison 2002 (1820–1992), averaging their “Extreme poverty” and “Poverty” percentages for commensurability with data on “Extreme poverty” for 1981–2015 from the World Bank 2016g.

The world’s progress can be appreciated in two ways. By one reckoning, the proportions and per capita rates I have been plotting are the morally relevant measure of progress, because they fit with John Rawls’s thought experiment for defining a just society: specify a world in which you would agree to be incarnated as a random citizen from behind a veil of ignorance as to that citizen’s circumstances.²⁴ A world with a higher percentage of long-lived, healthy, well-fed, well-off people is a world in which one would prefer to play the lottery of birth. But by another reckoning, absolute numbers matter, too. Every additional long-lived, healthy, well-fed, well-off person is a sentient being capable of happiness, and the world is a better place for having more of them. Also, an increase in the number of people who can withstand the grind of entropy and the struggle of evolution is a testimonial to the sheer magnitude of the benevolent powers of science, markets, good government, and other modern institutions. In the stacked layer graph in figure 8-5, the thickness of the bottom slab represents the number of people living in extreme poverty, the thickness of the top slab represents the number not living in poverty, and the height of the stack represents the population of the world. It shows that the number of poor people declined just as the number of all people exploded, from 3.7 billion in 1970 to 7.3 billion in 2015. (Max Roser points out that if news outlets truly reported the changing state of the world, they could have run the headline NUMBER OF PEOPLE IN EXTREME POVERTY FELL BY 137,000 SINCE YESTERDAY every day for the last twenty-five years.) We live in a world not just with a smaller proportion of extremely poor people but with a smaller number of them, and with 6.6 billion people who are not extremely poor.

Figure 8-5: Extreme poverty (number), 1820–2015

Sources:Our World in Data, Roser & Ortiz-Ospina 2017, based on data from Bourguignon & Morrison 2002 (1820–1992) and the World Bank 2016g (1981–2015).