If you asked a group of supposedly sophisticated people at Davos three simple questions about the world they live in, how would they do? This is not a theoretical question, since the late, great Hans Rosling did precisely that. In 2015, the Swedish professor of international health asked an audience that included heads of state, titans of industry and a former UN secretary-general three multiple-choice questions about poverty, population growth and vaccination rates. To his delight — and dismay — they scored worse than chimpanzees, doing just as badly as other audiences he had quizzed. (“Worse than chimpanzees” in Rosling-speak means “worse than random”.)

Rosling, who died last year as he was finishing this wonderful book, was on what he called a “lifelong mission to fight devastating global ignorance”. A man with an unparalleled ability to convey complex data in an entertaining and digestible fashion, he was convinced that the world was in much better shape than people realise. “Every group of people I ask thinks the world is more frightening, more violent, and more hopeless — in short, more dramatic — than it really is.”

Rosling’s message in Factfulness is an optimistic one — though he hates that description since, he argues, his views are rooted firmly in reality. He also acknowledges the possibility of sudden reversals as a result of catastrophes such as global warming, a pandemic disease, world war or financial collapse. He calls himself instead a “possibilist”. His contention is that like mindfulness, a dispassionate assessment of the facts has a calming effect because it reveals a world less divided and more prosperous than we realise.

Rosling backs up his ideas with an extraordinary ability to bring data to life. Progress in his native Sweden — which at the time of his birth in 1948 had the same levels of health and wealth as today’s Egypt — is illustrated by a story of his grandmother’s fascination with the washing machine. Having spent much of her life hand-washing clothes, she was so enthralled by the labour-saving device that when Rosling’s mother bought one, she would watch entire spin cycles as avidly as if she were enjoying television. That sort of transformative progress is happening all around the world today, says Rosling, including in south Asia and, increasingly, in urban Africa — a continent about which he is far more “possibilist” than most commentators.

On stage, Rosling would occasionally swallow a sword for dramatic effect or use a pointing stick with a little rubber hand attached. With his son and daughter-in-law, Ola and Anna, co-authors of the book, he developed software to convey complex data over time by representing countries as moving bubbles scaled to population size. His knack for presentation and delight in statistics come across on every page. Who else would choose a chart of “guitars per capita” as a proxy for human progress?

Rosling’s well-educated audience in Davos did not know that the world’s average life expectancy is 70, that 88 per cent of children are vaccinated against disease or that in 2100 there will be 2bn children below the age of 15 — the same number as today. Apart from in Africa, fertility rates have fallen so fast that populations have stabilised almost everywhere on Earth. One of Rosling’s favourite statistics is that in Muslim Bangladesh, women have fewer children than in Christian/atheist Sweden.

Routinely, Rosling finds that people have a more pessimistic view than warranted by the facts. When they are asked if, for example, “In the last 20 years, the proportion of the world population living in extreme poverty has a) almost doubled, b) remained more or less the same, or c) almost halved”, very few reply that it has almost halved. Rosling considers this to be a “pretty basic fact to know about life on Earth”, yet tested on thousands of people around the world, only 7 per cent get it right.

In a more contentious section of the book, he disputes the idea that there is a “gap” between the rich world and the developing one, a view that he calls 50 years out of date. In two charts, he presents a snapshot of the world in 1965 and 2017. Both plot babies per woman against children surviving to age five, the basic indicators needed to set people on a development journey from lightbulb to his grandmother’s washing machine. In 1965, most of the world, including India and China, is huddled towards the bottom left-hand corner with high birth rates and low survival rates. But by 2017, almost all have moved to the top right, where birth rates have fallen and child survival rates sharply improved. Only 6 per cent of the global population, living in 13 countries mostly locked in civil war, remain stuck in the box marked “developing”. The world has moved on, he says. Our worldview has not.

Our distorted picture stems partly from having media that (inevitably) report on tragedies such as starvation, war and school shootings, and from charities that accentuate the negative. Without ever dismissing suffering, he argues that we need to keep two ideas in our heads simultaneously: things can be bad but also improving. In one provocative chapter, he celebrates the fact that “only” 4.2m babies died last year, calling the number “beautifully small”. Rosling is a supremely humane man and his description jars. But his point is that in 1950, when the population was much smaller, there were 14.4m dead babies. We have made huge progress.

Rosling’s campaign to jolt us into reading the data more dispassionately is born of experience. Once, when he was working in Mozambique, he came across hundreds of patients in a poor coastal region with a debilitating disease that paralysed them in minutes. After two days of assessment, he reached the conclusion that the illness was the result of an unidentified poison, and therefore not contagious. But the mayor was determined to cordon off the area since he had to be seen to be doing something. Rosling consented. As a result, the villagers, desperate to get to market, boarded flimsy fishing boats. Many drowned. By departing from a cool-headed, rational approach to facts, Rosling felt that he had in fact contributed to the deaths of many people.

Rosling is no slave to data. He cares about numbers because they represent real lives. “Just as I have urged you to look behind the statistics at the individual stories, I also urge you to look behind the individual stories at the statistics,” he writes in words that sum up a passionate and erudite message that is all more moving because it comes from beyond the grave. “The world cannot be understood without numbers. And it cannot be understood with numbers alone.”

Factfulness: Ten Reasons We’re Wrong About the World — and Why Things are Better Than You Think, by Hans Rosling, Sceptre, RRP£12.99/Flatiron Books, RRP$27.99, 352 pages

David Pilling is the FT’s Africa editor

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