Tim Harford's Blog, page 40

Back to school

I hope you’ve had a wonderful summer – or winter, if you’re reading this in the southern hemisphere, or in early 2022. I’ve held off posting lots of August updates but now I’m back, and with a lovely little review of The Next Fifty Things That Made The Modern Economy (Amazon, Bookshop) from the Daily Mail.

“Tim Harford is an economist and broadcaster with a gift for making his subject fascinating and comprehensible to non-economists. His previous book, Fifty Things, was a series of quirky essays on the radical social change brought about by such inventions as the wheel and the internet. This sequel takes a close look at everyday inventions that we take for granted, but which, nevertheless, have a huge impact on our lives. Harford considers culture-changers from bricks (used to build the tower of Babel), bicycles (and their role in empowering women), and spectacles (there is a global epidemic of short-sightedness among children and no one knows why). Witty, informative and endlessly entertaining, this is popular economics at its most engaging.“

I cannot disagree. But if you don’t fancy buying a copy, I recommend taking a look at The Art of More (Bookshop), an enviably good history of how ideas in mathematics have shaped (and been shaped by) the progress of civilisation.

Also well worth a look is Machiavelli for Women by the superb economics journalist Stacey Vanek Smith.

If you want some Harford podcast action, More or Less is back on air – or here’s my interview with the Analytics Power Hour.

Or just enjoy this new and rather wonderful performance of Brian Eno’s Ambient 1: Music for Airports, from the Sydney Opera House.

From the clinical trial to role-playing games, why do some ideas arrive so late?

I confess, as a boy, to wearing a Leonardo da Vinci T-shirt. Da Vinci was my idea of cool, and the attraction lay not in the Mona Lisa’s smile or his sketches of natural phenomena. It was the helicopter. Nothing could be more awesome than a 15th-century thinker who could design a helicopter. It could never have flown, but who cares?

These days I am more interested in the reverse case: ideas that could have worked many centuries before they actually appeared. The economist Alex Tabarrok calls these “ideas behind their time”. Consider the bicycle. It was not produced in even the most primitive form until the early 1800s, and a practical version with chain drive was not widespread until the 1880s — just in time to compete with the motor car.

Anton Howes, author of Arts and Minds, points to the flying shuttle, invented in 1733. “It radically increased the productivity of weaving,” he writes. “It involved no new materials . . . and required no special skill or science.”

The craft that it transformed has been around long enough to be mentioned in the Old Testament. Steven Johnson, in his book Extra Life, suggests that evidence-based medicine is an idea behind its time. The idea of running experiments is centuries old, but the first properly randomised controlled trial in medicine took place in 1948. It could easily have been routine before da Vinci’s time, but instead clinical trials lagged far behind anaesthetic, antibiotics, antiseptic, pasteurisation and vaccines.

My favourite example is the tabletop role-playing game. Such games — a structured form of “let’s pretend” for grown-ups — could have been played in the villas of ancient Rome. But they didn’t emerge until 1969. The first commercial one, Dungeons & Dragons, was published in 1974.

Curious minds want to know why these ideas appeared so late — and whether there might be anything that would prevent delays in future. One explanation is that the ideas aren’t as simple as they appear. It was long thought that da Vinci had designed a bicycle in the late 1400s. He hadn’t — a bicycle sketch attributed to him turns out to be a 20th-century “addition” to his papers. But if he had done, it might have been barely more use than his helicopter. The bicycle is not as straightforward an invention as it seems. To move from ox-hauled cart to human-powered bicycle requires smooth-rolling wheel bearings, which in turn need precisely engineered bearing balls. Modern steel ball bearings were not patented until the late 1700s, and demand from the 19th-century bicycle industry helped to improve their design.

We often overrate the eureka moment of the inventor’s doodle and overlook the importance of materials to enable or inspire that idea. Dice, for example, would seem to point the way to the development of probability theory, which is based on counting combinations of equally likely outcomes. Perhaps the problem for ancient mathematicians was that they often rolled astragali — knucklebones. Uneven dice invited the idea that a roll was in the lap of the gods, impervious to rational analysis. When Girolamo Cardano produced his revolutionary ideas on probability in the 1500s, he had the advantage of playing with cubic dice.

Another obstacle to innovation is that people don’t make the right connections. The clinical trial, for example, sits on an uneasy border between medicine and statistics. The medical tradition emphasises the expertise of the doctor and the care of the patient as an individual. The statistical tradition picks patterns out of noise and uses methods that can be applied equally to brewing the perfect pint or testing the effect of fertiliser on crops. Combining the two is not an obvious step.

Two of the 20th century’s greatest statisticians were William S Gosset, who worked for Guinness, and Ronald A Fisher, whose career was shaped by a long stint in agricultural research. Both were at some remove from the medical establishment. The man who ran the 1948 clinical trial was neither purely a statistician nor purely a doctor: Austin Bradford Hill’s degree was in economics.

Maybe that explains the long wait for the invention of a game such as Dungeons and Dragons. It combines two contrasting traditions: one of imagination and improvisation; the other the complex and rule-following world of painstakingly researched historical war-games. Another issue is that many inventive people are pushed away from the world of innovations.

The economist Lisa Cook has studied obstacles for women and African-American inventors — “the innovation gap in pink and black”. Some of these obstacles were flagrant. Garrett Morgan, the African-American inventor of the gas mask and the traffic light, would often conceal his race, since some customers refused to buy on explicitly racist grounds. Other obstacles are more subtle.

Researchers at the Opportunity Insights project have analysed the phenomenon of “lost Einsteins”: young people (often girls or those from ethnic minorities or low-income families) who were discouraged because they never had an inventor as a role model.

But the simplest explanation of all is one advanced by Howes. Perhaps innovation does not come naturally. Most of us do things the way we see others doing them, the way they’ve always been done. The idea of a frustrated person becoming an inventor as they silently scream, “There must be a better way!” has become a cliché. Maybe that cliché is scarcer than we think.

Written for and first published in the Financial Times on 6 August 2021.

The paperback of “The Next 50 Things That Made The Modern Economy” is FINALLY coming – 26 August 2021. Please think about pre-ordering, which is hugely helpful in stimulating bookshops to stock and display the book.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

The secret to preventing killer heatwaves isn’t what you think

In July 1995, a hot, humid, slow-moving mass of air rolled over Chicago and stayed there for a week. Roads and railway tracks buckled. Lifting bridges were hosed down to prevent thermal expansion from locking them in place. Shops sold out of air conditioners. Demand for electricity led to blackouts. Then people started to die, simply unable to cope with the humidity and the heat day after day.

There is no official estimate for the death toll, but it is often reckoned to be more than 700 people. As with Covid-19, most were elderly, but epidemiologists later estimated that the majority of those older people were not otherwise in imminent danger of death.

The disaster received far less attention than, for example, the 1989 earthquake, which killed less than a tenth as many people in San Francisco and Oakland. This is not surprising. Heat does not look impressive on television. That said, the world did take notice of the refrigerated trucks sitting in the parking lot of the Cook County medical examiner’s office. They had been volunteered by a local meatpacking firm to help cope with the overflow of bodies from the morgue.

Heat continues to be a killer. The World Health Organization estimates that, between 1998 and 2017, 166,000 people died owing to heatwaves, a total that eclipses many more photogenic natural disasters.

Extreme heat is becoming more common. Professor Peter Stott of the Met Office in the UK told me that the recent heatwave in North America, when temperatures came close to 50C in Canada, could have been expected roughly every 60,000 years in the pre-industrial climate. In the modern world, warmed by many decades of greenhouse gas emissions, it could be expected once every 15 years or so.

We are going to have to get used to scorching temperatures and smothering humidity. Which makes it all the more important to understand what happened in Chicago a quarter of a century ago. Researchers from the US Centers for Disease Control and Prevention studied the problem carefully and concluded that “those at greatest risk of dying from the heat were people with medical illnesses who were socially isolated and did not have access to air conditioning”.

That’s not wrong, but neither is it especially helpful. Why did people have no access to air conditioning? The city was full of air-conditioned spaces, many of them — such as libraries and shops — open to anyone, free of charge. And why were people so cut off, even in a crisis? As the great urban observer Jane Jacobs told the Chicago Sun-Times back then, “It took a lot of effort to make people this isolated.”

In his 2002 book Heat Wave: A Social Autopsy of Disaster in Chicago, the sociologist Eric Klinenberg went beneath the surface of the catastrophe. The CDC analysis had compared pairs of individuals, contrasting those who had died with apparently similar individuals who had not. Klinenberg compared two adjacent Chicago neighbourhoods: North Lawndale and South Lawndale.

North Lawndale had a heatwave death rate 10 times higher than South Lawndale. Why? Both neighbourhoods had plenty of poor elderly people living alone and both were overwhelmingly non-white. But in other ways they were different.

North Lawndale was depopulated, an urban desert with vacant lots. Gangs used it as a convenient place to sell drugs. “We used to sit outside all night and just talk,” said one resident. But with bullets flying, that became impossible. Big employers such as International Harvester, Sears Roebuck and Western Electric had moved away and shops had closed. People didn’t leave their apartments because they were afraid of being mugged or burgled. They weren’t used to walking to local shops — and there weren’t many local shops to walk to.

South Lawndale, by contrast, was overcrowded, but as a result it felt bustling — and safe. (The area is now known as “Little Village”.) You could step outside your door any time and there would be folk around. When the heatwave struck, elderly residents were happy to walk into an air-conditioned store nearby and hang out. They felt safe leaving an empty apartment behind. When at home they felt safe opening their doors to the people who came to check on them. In a heatwave, lively streets save lives.

Neighbourhoods can also be heatwave-prone or heatwave-resistant in more literal ways, as a recent article in Nature argues. A city block with tarmac and concrete, little shade and rapid drainage of water can be several degrees hotter than one with the shade of trees or patches of vegetation that catch water and let it evaporate. It will surprise no one that leafy, richer neighbourhoods tend to be cooler.

The effect is large. A recent study in the journal Climate found that historically “redlined” areas in US cities — mostly African-American, denied federal mortgage support in the 1930s and long marginalised afterwards — are an average of 2.6C warmer.

It is all rather depressing, but there is an opportunity too. It is inevitable that we will have to adapt to climate change, and adaptation is often thought of as an expense: vast dykes, flood barriers and weatherproofing. But if adaptation to climate change means supporting vibrant neighbourhoods, planting trees, reducing crime and encouraging local businesses, that is something we would surely want to do, regardless of what the climate holds.

Written for and first published in the Financial Times on 30 July 2021.

The paperback of “The Next 50 Things That Made The Modern Economy” is FINALLY coming – 26 August 2021. Please think about pre-ordering, which is hugely helpful in stimulating bookshops to stock and display the book.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

Espionage, assassination, and the modern factory

Piedmont, in North West Italy, is celebrated for its fine wine. But when a young Englishman, John Lombe, travelled there in the early eighteenth century, he wasn’t going to savour a glass of Barolo. His purpose was industrial espionage. Lombe wished to figure out how the Piedmontese spun strong yarn from silkworm silk. Divulging such secrets was illegal, so Lombe sneaked into a workshop after dark, sketching the spinning machines by candlelight. In 1717, he took those sketches to Derby in the heart of England.
Local legend has it that the Italians took a terrible revenge on Lombe, sending a woman to assassinate him. Whatever the truth of that, he died suddenly at the age of 29, just a few years after his Italian adventure.
While Lombe may have copied Italian secrets, the way he and his older half-brother Thomas used them was completely original. The Lombes were textile dealers, and seeing a shortage of the strong silk yarn called organzine, they decided to go big.
In the centre of Derby, beside the fast-flowing River Derwent, the Lombe brothers built a structure that was to be imitated around the world: a long, slim, five-storey building with plain brick walls cut by a grid of windows. It housed three dozen large machines powered by a 7-metre-high waterwheel. It was a dramatic change in scale, says the historian Joshua Freeman in his book Behemoth. The age of the large factory had begun with a thunderclap.
It’s a testament to the no-nonsense functionality of the Derby silk mill that it operated for 169 years, pausing only on Sundays, and for droughts – when the Derwent flowed slow and low. Over that period, the world economy grew more than fivefold, and factories were a major part of that growth.
Intellectuals took note. Daniel Defoe, author of Robinson Crusoe, came to gaze in wonder at the silk mill. Adam Smith’s The Wealth of Nations, published in 1776, begins with a description of a pin factory. Three decades later, William Blake had penned his line about ‘dark Satanic Mills’.
Concerns about the conditions in factories have persisted ever since. The ‘Round Mill’, built in 1811 not far from the Derby silk mill, was modelled after Jeremy Bentham’s famous ‘Panopticon’ prison, a place where you never knew whether you were being watched. The circular design did not catch on, but the relentless scrutiny of workers did.
Critics claimed that factory exploitation was a similar evil to slavery – a shocking claim then and now. After visiting the mills of Manchester in 1832, the novelist Frances Trollope wrote that factory conditions were ‘incomparably more severe’ than those suffered by plantation slaves. Indeed, the factory recruiting wagons that toured the rural areas of 1850s of Massachusetts, hoping to persuade ‘rosy-cheeked maidens’ to come to the city to work in the mills, were dubbed the ‘slavers’.
Friedrich Engels, whose father owned a Manchester factory, wrote powerfully about the harsh conditions, inspiring his friend Karl Marx. But Marx, in turn, saw hope in the fact that so many workers were concentrated together in one place: they could organise unions, political parties, and even revolutions. He was right about the unions and the political parties, but not about the revolutions: those came not in industrialised societies but agrarian ones.
The Russian revolutionaries weren’t slow to embrace the factory. In 1913, Lenin had skewered the stopwatch-driven, micromanaging studies of Frederick Winslow Taylor as ‘advances in the extortion of sweat’. After the revolution, the stopwatch was in the other hand. Lenin announced: ‘We must organize in Russia the study and teaching of the Taylor system.’
In developed economies, the dark satanic mills gradually gave way to cleaner, more advanced factories. It is the working conditions of factories in developing countries that now attract attention. Economists have tended to believe both that sweatshop conditions beat the alternative of even more extreme poverty in rural areas – and that they have certainly been enough to draw workers to fast-growing cities. Manufacturing has long been viewed as the engine of rapid economic development.

So what lies next for the factory? History offers several lessons.
Factories are getting bigger. The eighteenth-century Derby Silk Mill employed three hundred workers, a radical step at a time when even machine-based labour could take place at home or in a small workshop. The nineteenth-century Manchester factories that had horrified Engels could employ more than a thousand, often women and children. Modern factories in advanced economies are much larger still: Volkswagen’s main factory in Wolfsburg, Germany employs over 60,000 workers; that’s half the population of the town itself.
And the Longhua Science and Technology Park in Shenzhen, China – better known as ‘Foxconn City’ – employs at least 230,000 workers, and by some estimates 450,000, to make Apple’s iPhones and many other products. These are staggering numbers for a single site: the entire McDonald’s franchise worldwide employs fewer than 2 million.
The increase in scale isn’t the only way in which Foxconn City continues the arc of history. There are – as there were in the 1830s – fears for the welfare of workers. In Shenzhen, they are dissuaded from suicide by nets designed to catch anyone who leaps from the factory roof.
But Leslie Chiang, who has interviewed many Chinese factory workers, notes that they know what they’re doing and don’t need the guilt of Western consumers. One of them, Lu Qingmin, had developed a career in the factories, met her husband, brought up a family – and saved enough to buy a second-hand Buick. ‘A person should have some ambition while she is young,’ she declared.
Large strikes are commonplace in China, as Marx might have predicted. The Chinese government, in one of history’s great ironies, is cracking down on the young Marxists who try to get the workers unionised.
And as in the West many decades before, there is progress: the journalist James Fallows, who has visited 200 Chinese factories, notes that conditions have dramatically improved over time.
Trade secrets kick-started the first factory, and have shaped factories ever since. Richard Arkwright, whose cotton mill was modelled on the Lombe brothers’ silk mill, vowed, ‘I am Determind for the feuter [future] to Let no persons in to Look at the wor[k]s.’ Chinese factories are still secretive: Fallows was surprised to be allowed into the Foxconn plant, but he was told that he must neither show nor mention the brand names coming off the production lines.
There is one clear break from the past. Factories used to centralise the production process: raw materials came in, finished products went out. Components would be made on site or by suppliers close at hand. Charles Babbage, factory enthusiast and Victorian designer of proto-computers, pointed out that this saved on the trouble of transporting heavy or fragile objects in the middle of the manufacturing process.
But today’s production processes are themselves global. Production can be coordinated and monitored without the need for physical proximity, while shipping containers and bar codes streamline the logistics. Modern factories – even behemoths like Foxconn City – are just steps in a distributed production chain. Components move backwards and forwards across borders in different states of assembly.
Foxconn City, for example, doesn’t make iPhones: they assemble them, using glass and electronics from Japan, Korea, Taiwan and even the USA. Huge factories have long supplied the world. Now the world itself has become the factory.

This essay is an extract from “The Next 50 Things That Made The Modern Economy” which was published in UK paperback yesterday.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

Resist the temptation to overachieve on holiday

As the northern hemisphere limps to whatever summer tourism it can muster, I am starting to dream of the epic holiday I will enjoy when I am finally able. What will yours be? And will you truly live your holiday — and indeed your life — to the max? Will you see dawn break over Florence from the Piazzale Michelangelo? Will you savour the freshest tamales in the market at Oaxaca? Will you sing karaoke into the early hours in Roppongi? (If so, I hope you capture it all on Instagram.) And if you do see dawn break over Florence, won’t some part of you wonder if it shouldn’t have been Oaxaca or Roppongi instead?

The world is wide and full of wonders. On this point, a recent New Yorker cartoon is worth a thousand words. It depicts a man sitting in bed, sheets tucked under his chin, haunted insomniac eyes staring, the bedside clock reading 2.37. The thought bubble reads, “Once again, I have failed to take full advantage of all New York has to offer.” The pressure to be productive is everywhere, even in time off. Once you’ve cleared your inbox, you can start ticking off the list of galleries in Paris, or Thai islands, or Great Novels To Read Before You Die. But is it not always thus? How often can we honestly look back at our day and say that not a minute was squandered? It is exhausting when it happens. We cannot burn brightly every day. Yet it is so easy to become regretful.

As Oliver Burkeman points out in his new book, Four Thousand Weeks, we risk holding ourselves to standards of productivity and achievement that no human could ever reach. A related but distinct problem is what the writer Adam Gopnik called the “Causal Catastrophe”, which is that we risk judging every action not in its own right, but by its long-term consequences. Gopnik was writing about parenting and the idea that how you feed, comfort or play with your baby should be evaluated by what sort of adult that baby becomes. Alas, the consequences of snuggle time are imponderable, uncontrollable and effectively unobservable. Meanwhile, there is a real baby in front of you. Don’t blink and miss it.

The Causal Catastrophe lurks everywhere. Why do you want to go to university? To improve your job prospects, to earn money, to pay for retirement. Why do you want to learn to run 5K? Because then you’ll be able to run a marathon, and the marathon will let you raise money for charity. Why do you want to go on holiday? Because you need to rest and recharge so that you will be able to work more productively when you return. It all sounds so reasonable, except that if everything is done as a means to something else, nothing is worthwhile in itself.

In Toni Morrison’s novel Sula, in a conversation between embittered former friends, the protagonist Sula declares,

“I sure did live in this world.”

“Really? What have you got to show for it?”

“Show? To who?”

Exactly. Life is not a rehearsal, but neither is it a performance.

I find that one of the most relaxing moments of the holiday is often just before it starts, and this is because it forces clear decisions. Suddenly every task on the To Do list can be divided into “have to do this before I go” and “this can wait until I get back”. This productivity guillotine has been blunted by the ability to work on the move, but it remains sharp enough to bite. A good time-management system offers the same promise of clarity every day, the same inner peace that comes from feeling confident that you’re spending your time wisely. But while the promise is not completely hollow, there is a trap in waiting for the moment when all the decks are clear, everything is under control and the rest of life can begin. The trap is that such moments can only ever be fleeting. There is always more coming in — whether it’s small, such as a new email or a new neighbourhood restaurant, or as life-changing as a cancer diagnosis. The decks will always be messy and we should not wish things otherwise.

The best holiday I ever had was my honeymoon, in 2003. We walked for nearly a fortnight, coast to coast across the UK. Honeymoons are supposed to be fun, of course, but I think there was more behind the bliss of this one. It was that the holiday was enough, and we were enough for each other. There was no anxiety that we should be doing anything different. The wedding was joyful, but also represented the completion of a very long To Do list. The thank-you letters couldn’t be written until we got home. I’d just quit my job (and was looking forward to an internship at the Financial Times). The decks really were clear. There were no choices to make. We had committed. There was no point in looking for shortcuts or distractions. There was nothing to do except enjoy the journey.

Written for and first published in the Financial Times on 13 August 2021.

The paperback of “The Next 50 Things That Made The Modern Economy” is now out in the UK.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

The stamp at the bottom of the pyramid

‘It should be remembered, that in few departments have important reforms been effected by those trained up in practical familiarity with their details. The men to detect blemishes and defects are among those who have not, by long familiarity, been made insensible to them.’
Those words are from 1837. An early pitch from an aspiring management consultant? No: that profession was still nearly a century off. But it was, in effect, the service Rowland Hill had taken it upon himself to perform for Great Britain’s postal service.
Hill was a former schoolmaster, whose only experience of the Post Office was as a disgruntled user. Nobody had asked him to come up with a detailed proposal for completely revamping it. He did the research in his spare time, wrote up his analysis, and sent it off privately to the British finance minister, the Chancellor of the Exchequer, naively confident that ‘a right understanding of my plan must secure its adoption’.
He was soon to get a lesson in human nature: people whose careers depend on a system, no matter how inefficient it might be, won’t necessarily welcome a total outsider turning up with a meticulously argued diagnosis of its faults and proposal for improvements. ‘Utterly fallacious . . . most preposterous’ fulminated the Secretary of the Post Office, Colonel Maberly; ‘wild . . . extraordinary’ added the Earl of Lichfield, the Postmaster-General.
Brushed off by the Chancellor, Hill changed tack. He printed and distributed his proposals, under the title ‘Post Office Reform: Its Importance and Practicability’. He added a preface, explaining why his very lack of experience in the postal service qualified him to detect its ‘blemishes and defects’. He wasn’t the only person frustrated with the system, and everyone who read his manifesto – and who wasn’t employed by the Post Office – agreed that it made perfect sense. The Spectator campaigned for Hill’s reforms. There were petitions. The Society for the Diffusion of Useful Knowledge made representations. Within three years, the government had bowed to public pressure, and appointed a Post Office supremo: Rowland Hill himself.

What were the problems Hill identified? Back then, you didn’t pay to send a letter. You paid to receive one. The pricing formula was complicated and usually prohibitively expensive. If the postman knocked on your door in Birmingham, say, with a three-page letter from London, he’d let you read it only if you coughed up two shillings and threepence. That wasn’t far below the average daily wage, even though ‘the whole missive might not weigh a quarter of an ounce’.
People found workarounds. Members of Parliament could send letters that would be delivered free of charge – if you happened to know one, they might ‘frank’ your letters as a favour. The free-franking privilege was widely abused – by the 1830s, MPs were apparently penning an improbable 7 million letters a year. Another common trick was to send coded messages through small variations in the address. You and I might agree that if you sent me an envelope addressed ‘Tim Harford’, that would signify you were well; if you addressed it ‘Mr. T. Harford’, I would understand you needed help. When the postman knocked, I would inspect the envelope, and refuse to pay.
Hill’s solution was a bold two-step reform. Senders, not recipients, would be asked to pay for postage; and it would be cheap – one penny, regardless of distance, for letters up to half an ounce. Hill thought it would be worth running the post at a loss, as ‘the cheap transmission of letters and other papers . . . would so powerfully stimulate the productive power of the country’. But he made a powerful case that profits would actually go up, because if letters were cheaper to send, people would send more of them.
Economists would recognise the question Hill was trying to answer: how steep was the demand curve? If you reduced the price, by how much would demand increase? Hill didn’t know about demand curves: the first such diagram was published in 1838, the year after his proposal. But he knew how to marshal anecdotes: the brother and sister in Reading and Hampstead, some 40 miles apart, who lost touch for three decades, then corresponded frequently when a kindly MP gave them some free-franks. It had only been the expense that put them off.
A few years ago the Indian-born economist C. K. Prahalad argued that there was a fortune to be made by catering to what he called ‘the bottom of the Pyramid’, the poor and lower-middle class of the developing world. They didn’t have a lot of money as individuals, but they had a lot of money when you put them all together. Rowland Hill was more than a century and a half ahead of him. He pointed to a case when small payments from large numbers of poor people had mounted up for the government: duties on ‘malt and ardent spirits (which, beyond all doubt, are principally consumed by the poorer classes)’ brought in much more than those on ‘wine (the beverage of the wealthy)’. Hill concluded, slightly disparagingly:

The wish to correspond with their friends may not be so strong, or so general, as the desire for fermented liquors, but facts have come to my knowledge tending to show that but for the high rate of postage, many a letter would be written, and many a heart gladdened too, where the revenue and the feelings of friends now suffer alike.

In 1840, the first year of penny post, the number of letters sent more than doubled. Within ten years, it had doubled again. Hill initially expected that postage-paid envelopes would be more popular than stamps – but the ‘Penny Mulready’ envelope faded into obscurity, while the ‘Penny Black’ stamp inspired the world. It took just three years for postage stamps to be introduced in Switzerland and Brazil; a little longer in America; by 1860, ninety countries had them. Hill had shown that the fortune at the bottom of the pyramid was there to be mined.
Cheap postage brought the world some recognisably modern problems: junk mail, scams, and a growing demand for immediate response – half a century on from Hill’s penny post, deliveries in London were as frequent as hourly, and replies were expected by ‘return of post’.
But did the penny post also diffuse useful knowledge, and stimulate productive power? The economists Daron Acemoğlu, Jacob Moscona and James Robinson recently came up with an ingenious test of this idea in the United States. They gathered data on the spread of post offices in the nineteenth century, and the number of applications for patents from different parts of the country. New post offices did indeed predict more inventiveness, just as Hill would have expected.
Nowadays, what we call ‘snail mail’ looks to be in terminal decline. There are so many other ways to gladden our friends’ hearts. Forms and bank statements are going online; even junk mail is in decline, as spamming us online is more cost-effective: every year, across the developed world, the number of letters sent drops by another few per cent. Meanwhile, the average office worker gets well over a hundred emails a day. We no longer need societies to promote the diffusion of useful knowledge – we need better ways to distil it.
But Acemoğlu and his colleagues think the nineteenth-century postal service has a lesson to teach us today: that ‘government policy and institutional design have the power to support technological progress’. What current blemishes and defects in these areas might be holding progress back? We need the successors of Rowland Hill to tell us.

This essay is an extract from “The Next 50 Things That Made The Modern Economy” the paperback of which is out this week in the UK. “Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

The joy of the humble brick

‘I found Rome a city of bricks and left it a city of marble.’ That is supposed to have been the boast of Caesar Augustus, the first Roman emperor, just over two thousand years ago. If it was, he was exaggerating: ancient Rome is a city of brick, and no less glorious for that.
Augustus was also joining a long tradition of denigrating or overlooking one of the most ancient and versatile of building materials. The great Roman architectural writer Vitruvius mentions them only in passing. Denis Diderot’s great French Encyclopaedia ‘of the Sciences, Arts and Crafts’, published in 1751 and an inspiration for Adam Smith’s famous description of the pin factory – well, Diderot doesn’t trouble himself to include any images of brickmaking at all.
That’s because a brick is such an intuitive thing: people have been teaching themselves to build simple structures out of brick for many thousands of years – and grand ones too. The Hanging Gardens of Babylon were made of brick. So was the biblical tower of Babel: ‘Come, let’s make bricks and bake them thoroughly.’ That’s Genesis 11 verse 3. ‘They used brick instead of stone.’ By verse 5, The Lord is on the scene and things aren’t looking too good for the brick-loving citizens of Babel.
As James Campbell and Will Pryce point out in their magisterial history of bricks, the humble cuboid is everywhere. The biggest man-made structure on the planet, the Ming Dynasty Great Wall of China, is largely constructed of brick. The astonishing temples of Bagan in Myanmar; mighty Malbork Castle in Poland; Siena’s Palazzo and Florence’s Duomo; the bridges of Isfahan in Iran; Hampton Court Palace in West London. All brick. So is the best church in the world, Hagia Sophia in Istanbul, and the best skyscraper, the Chrysler Building in Manhattan, and even the Taj Mahal. Brick. Brick. Brick. The architect Frank Lloyd Wright once boasted that he could make a brick worth its weight in gold.
This all started a long time ago; bricks seem to have been with us since the very dawn of civilisation – the oldest were found in Jericho, in Jordan, by the archaeologist Kathleen Kenyon in 1952. They are something between 10,300 and 9,600 years old, and are simply loaves of mud, baked dry in the sun, then stacked up and glued together with more mud.
The next big step forward was the simple brick mould, also originating from Mesopotamia, at least 7,000 years old, and depicted with great clarity on a tomb painting in Thebes, Egypt. The brick mould is a wooden rectangle, with four sides but no top or bottom, into which clay and straw could be packed to make bricks faster and more precisely. These moulds can’t have been easy to make – they pre-date the use of metal itself – but once constructed they made mud bricks much cheaper and better.
Even in a dry climate, sun-dried mud bricks do not usually last. Fired bricks are much more durable – they’re stronger, and waterproof. Making such bricks, by heating clay and sand at a temperature of about 1,000° centigrade, has been possible for many thousands of years – but at a price. Accounts from the Third Dynasty of Ur, dating back just over 4,000 years, note that you could get 14,400 mud bricks for the price of a piece of silver; but only 504 fired clay bricks – an exchange rate of nearly 29 mud bricks for a single clay one. Some 1500 years later, by Babylonian times, kiln technologies had improved and the price of fired clay bricks had fallen to between 2 and 5 mud bricks.
That’s still too much for many people – cheap and easy mud bricks are still perhaps the most popular material in the world for building houses. But, as the Nobel prize-winning economists Abhijit Banerjee and Esther Duflo observe, fired bricks can be an effective way for a very poor household to save. If you have a little money, buy a brick or two. Slowly, slowly, slowly, you’ll have a better house.
The brick is one of those old technologies, like the wheel or paper, that seem to be basically unimprovable. ‘The shapes and sizes of bricks do not differ greatly wherever they are made,’ write Edward Dobson in the fourteenth edition of his Rudimentary Treatise on the Manufacture of Bricks and Tiles. There’s a simple reason for the size: it has to fit in a human hand. As for the shape, building is much more straightforward if the width is half the length.
That’s why, if you get your nose up close to some buildings that seem vibrantly distinctive to their culture – the Minaret of Kalan Mosque in Uzbekistan, Herstmonceux Castle in England, the Twin Pagodas of Suzhou in China – you’ll find the bricks are all much the same. It’s precisely the uniformity of the brick that makes it so versatile – a lesson freshly rediscovered by every generation of parents when their children start playing with Lego.
Lego, by the way, point out that their plastic bricks don’t need to be sent for recycling because they can be reused almost indefinitely. And what is true for toy bricks is truer yet for the real thing. Lego’s interlocking bricks demand a high level of precision – the fault rate is just 18 per million. But bricks jointed with mortar have a higher tolerance. Many medieval buildings, such as St Alban’s Cathedral in England, simply reused Roman bricks. Why not?
‘Bricks manage time beautifully.’ That’s Stewart Brand in his book and TV series, How Buildings Learn. ‘They can last nearly forever. Their rough surface takes a handsome patina that keeps improving for centuries.’ My own house, a brick building from the mid-nineteenth century, now has a large glass door in the back. To make the hole for the glass, we took away some bricks. Then we mixed them with similar reclaimed bricks, and used the brick salad to extend the house elsewhere.
Brick production still uses traditional methods in many parts of the world – for example in India, handmade bricks are often fired using a Bull’s Trench kiln – a long ditch lined with bricks that can burn almost any fuel and produce 30,000 bricks a day. It may be fuel-hungry and polluting, but it uses local labour and materials.
But automation is gradually nosing its way into most parts of brick production: hydraulic shovels dig the clay; slow conveyor belts carry bricks through long tunnel kilns; forklift trucks shift precision-stacked pallets of bricks. All this makes the brick itself cheaper.
Building sites have resisted automation: the weather and the unique demands of each site require well-trained workers. The bricklayer has long been celebrated as a symbol of the honest dignity of skilled manual labour, and bricklaying tools have barely changed since the seventeenth century. But, as in so many other professions, there are signs that the robots may be coming to bricklaying. A human bricklayer can lay 300–600 bricks a day; the designers of SAM, the Semi-Automated Mason, claim it can do 3,000.
What of the brick itself? Various designs of interlocking brick, much like Lego, are catching on across the developing world: the result tends to be less strong and waterproof than bricks and mortar, but they’re quicker and cheaper to lay. And if you have robot bricklayers, why not give them bigger hands so you can make bigger bricks? Hadrian X is a robot arm which lays gigantic bricks that no human bricklayer could wield.
Maybe we shouldn’t get too excited, though. SAM has a predecessor – the ‘Motor Mason’, for which similar claims were made back in 1967. Perhaps the bricklayer will last a little longer yet. The brick certainly will.

This essay is an extract from “The Next 50 Things That Made The Modern Economy” – the paperback is out this week in the UK.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

Five truths about covid that defy our intuitions

It’s striking how much Covid confusion still reigns. Some of the informational miasma is deliberate — there’s profit for some in the bewilderment of others — but much of it stems from the fact that epidemics defy our intuition. So, here are five counterintuitive Covid truths that easily slip beyond our understanding:

1. If a large share of hospitalised people are vaccinated, that’s a sign of success. It has been common to see headlines noting that a substantial minority of people who have been hospitalised or even killed by Covid have been fully vaccinated. These numbers suggest vaccine failure is alarmingly common. The fallacy only becomes clear at the logical extremes: before vaccines existed, everyone in hospital was unvaccinated; if vaccines were universal, then everybody in hospital would be vaccinated. Neither scenario tells us whether the vaccines work.

So try this. Imagine that 1 per cent of the unvaccinated population will end up in hospital with Covid over a given time period. In a city of a million people, that would be 10,000 hospital stays. Now let’s say that 950,000 people get fully vaccinated, that the vaccine is 95 per cent effective against hospitalisation, and that the vaccine doesn’t reduce transmission (although it does). Here’s the arithmetic: 500 of the 50,000 unvaccinated people end up in hospital. A total of 9,500 of the vaccinated people would be at risk of a hospital visit, but the vaccine saves all but 5 per cent of them. These unlucky 475 still go to hospital. The hospital contains 500 unvaccinated and 475 vaccinated people — almost half and half — which makes it seem as though the vaccine barely works. Yet when 95 per cent of people take a 95 per cent effective vaccine, hospital visits fall from 10,000 to fewer than 1,000.

2. Herd immunity isn’t the end of a pandemic. In the simplest epidemiological models, herd immunity is the moment when so many people are immune — either because of vaccines or prior infection — that the epidemic begins to die away of its own accord. The keyword here is “begins”. An epidemic has momentum, like a train. Herd immunity is the beginning of an uphill gradient, initially very gentle. If the train is moving at top speed as it begins to climb the hill, it will keep travelling for a long way before it stops. The difference between hitting herd immunity during a raging epidemic — yes, I am thinking of the UK — and hitting it through vaccination during a lull could be millions of unnecessary cases.

3. Masks matter, but not for the reason you think. Microbiologist Ravi Gupta has called the end of mask mandates in England “criminal”, while radio presenter Julia Hartley-Brewer has said she will boycott the bookshop Waterstones if they politely suggest wearing masks. What is it about masks that ignites such rhetoric? This is all about the social stakes involved. While you can’t see who’s been vaccinated or who has ignored a ping from the contact tracers, you can see who’s wearing a mask. I think it is considerate to wear a mask, an act that evidence suggests may protect me, probably protects others and certainly reassures them. For most people, wearing a mask is only a minor annoyance, so why not do it? Only our innate tribalism can turn mask-wearing from a simple, promising precaution into the dividing line between the saintly and the damned.

Cabinet ministers have boasted about removing their masks as soon as possible, which feels like boasting about farting in a lift: it might be a relief but it’s a strange thing to advertise. Once one realises this is about signalling tribal loyalty, it makes more sense.

4. Lockdowns also matter less than you think. It is understandable that we have focused so much on lockdowns. The radical social distancing ministers have imposed has been an unprecedented shift in the way we live, but it has saved millions of lives. What we overlook is that much of this social distancing would have happened anyway. Many people “locked down” before lockdowns themselves, out of fear or out of consideration for others, or both. The most famous study of this by economists Austan Goolsbee and Chad Syverson estimated that around 90 per cent of the reduction in consumer traffic was voluntary.

One need not believe the precise number to accept that people have often acted by choice, through fear or altruism. The flip side is also true: a lockdown that isn’t widely supported is neither effective nor tenable. All this matters because it is easy to think that everything revolves around the rules. More important is social solidarity, clear information and prominent people setting a good example. Alas, we’ve had to settle for social solidarity alone.

5. Covid was a near miss. After the disruption to life, love, education and commerce, and after more than four million confirmed deaths around the world — with many more unconfirmed and many still to come — it may seem strange to say so. But this could have been far worse. It could have been as contagious (or more) as the Delta variant from day one. It could have been as deadly as Mers, which has killed a third of the people confirmed to have contracted it. It could have attacked children rather than the very elderly. And it could — like HIV — have defeated efforts to create a vaccine. So while we count the cost, we should also count our blessings — and dramatically strengthen our preparedness for the next pandemic.

Written for and first published in the Financial Times on 23 July 2021.

The paperback of “The Next 50 Things That Made The Modern Economy” is FINALLY coming – 26 August 2021. Please think about pre-ordering, which is hugely helpful in stimulating bookshops to stock and display the book.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.

A live speech at last, and other news

I’m speaking at the FT Weekend Festival (in a well-ventilated tent in Hampstead) – do come along!

If you prefer your speeches online, you might enjoy this discussion with UCL economics students, in which we cover carbon taxes, thinking like a statistician, and the importance (or otherwise) of patents for vaccines.

More or Less is returning to Radio 4 on Wednesday 1st September – please send your questions and comments to moreorless@bbc.co.uk.

I’ve been enjoying some holiday reading – too many books to summarise – but I would direct your attention to:

Steven Pinker’s The Sense of Style, a useful and highly enjoyable book about clear writing.

Roland Huntford’s The Last Place on Earth, a really gripping book about the rivalry between Scott and Amundsen. (I am no great admirer of Scott but Huntford occasionally seems to me to go too far in his criticism; that said the combination of vivid storytelling and careful historical detail is very compelling). Next I clearly need to read Ranulph Fiennes, who I understand disagrees vociferously.

Finally a reminder that The Next Fifty Things That Made The Modern Economy is out in the UK, Ireland, India, Australia and many other places very shortly. It’s a book telling the story of fifty different inventions – and more importantly, the way they shaped the world and the lessons they can teach us about how the modern world works. Pre-ordering from Bookshop, Amazon or your favourite local retailer would be enormously helpful, so thank you in advance!

Book Review – Thinking Better: The Art of the Shortcut, by Marcus du Sautoy

In 1786, in a classroom in Braunschweig, near Hanover, a bored schoolmaster in need of a nap set his pupils the tedious task of adding up every number between 1 and 100. Before the master could even lean back in his chair, one boy strode forward and placed his slate on the front desk.

Ligget se, he casually declared. There it is. And there it was: 5050. Carl Friedrich Gauss, at the age of nine, had announced his mathematical genius to the world.

Marcus du Sautoy begins his book about shortcuts not with the story, but with the story of the story. Du Sautoy explains that he, like Gauss, was a schoolboy sitting in a maths class when his teacher told the tale (which has been heavily embellished over the years) and explained that mathematics was “the art of the shortcut”.

1 + 100 = 101
2 + 99 = 101
3 + 98 = 101

Once you see that there are 50 pairs of numbers, each summing to 101, the answer — 5050 — is not far away.

At this moment a new vision of mathematics opened up for du Sautoy, “the ability to see structure in our mind’s eye without physically encountering it”. Mathematical shortcuts offer easy ways to solve difficult puzzles, or the mass production of solutions so that a problem need only be solved once to unlock every similar problem.

Du Sautoy is a gifted and tireless mathematical communicator with considerable range — his Brief History of Mathematics was masterful radio, and I’ve seen him compère concerts of classical music, interspersing the pieces with discussions of the mathematical patterns in Mozart and Bach.

In Thinking Better, he pauses between each mathematical chapter to interview experts in many domains, hoping to gain the secret to shortcuts in learning a language (he once studied Russian) or mastering the cello (Du Sautoy is a keen trumpeter).

These interludes are pleasant enough but feel distant from the mathematical ideas in the book. Virtuoso Natalie Clein explains that the secret to mastering the cello is endless, focused practice; no surprise there. A champion memoriser opines that if du Sautoy wants to improve his Russian, he needs repetition and testing — or, more promisingly, a Russian lover.

The joy of du Sautoy’s book isn’t really the art of the real-world shortcut at all. It is the romp through mathematical ideas

The reader who desires plausible shortcuts to real-life mastery might pick up a copy of Robert Twigger’s Micromastery, which advocates focus (to learn to cook, first learn to make a truly superlative omelette). Algorithms to Live By, by Brian Christian and Tom Griffiths, pulls surprising practical insights out of mathematical techniques — using computer science to explain how to sort your bookshelves, search for a new apartment, or organise piles of paper on your desk.

In contrast, the joy of du Sautoy’s book isn’t really the art of the real-world shortcut at all. It is the romp through mathematical ideas, from place value to non-Euclidean geometry to probability theory. He finishes with “NP-complete” problems, an important field in modern computing. A pithy explanation of what they are eludes me, but du Sautoy’s own description is the best I’ve seen: they’re “needle in a haystack” problems, because while it is very hard to find the needle, if you suspect you have succeeded it is very easy to check.

He frames this as a chapter about problems for which there seem to be no shortcuts, and ranges from quantum computing to problem-solving by slime moulds. He even includes the surprisingly difficult challenge of calculating which teams are still in with a mathematical prospect of winning the Premier League. (It was much easier when only two points were awarded for a win, rather than three, because the total number of points awarded in each game did not change.)

At times the reader needs to concentrate hard, because du Sautoy doesn’t shy away from equations or challenging ideas. He is, however, always a model of clarity. There are vivid historical examples of scientists and others using mathematical ideas to solve problems, from Eratosthenes calculating the circumference of the Earth to Florence Nightingale deploying data visualisation to make a powerful argument about public health. Columbus, Galileo, Alan Turing and Samuel Pepys all make appearances.

Many of the stories and examples — beginning with Gauss’s alleged feat of calculation — will be familiar to people who enjoy popularisations of mathematics. Du Sautoy’s mash-ups of art, music and mathematics have sometimes pushed the boundaries of mathematical popularisation in unusual directions, but here he mostly plays it straight. This is a “greatest hits” of mathematical ideas presented with trademark clarity and energy.

Written for and first published in the Financial Times on 3 August 2021.

The paperback of “The Next 50 Things That Made The Modern Economy” is FINALLY coming – 26 August 2021. Please think about pre-ordering, which is hugely helpful in stimulating bookshops to stock and display the book.

“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson

“Harford is a fine, perceptive writer, and an effortless explainer of tricky concepts. His book teems with good things, and will expand the mind of anyone lucky enough to read it.”- The Daily Mail

I’ve set up a storefront on Bookshop in the United States and the United Kingdom – have a look and see all my recommendations; Bookshop is set up to support local independent retailers.