Steven Johnson: Yes, most of us walk around with an idea of what drives change in society and where big transformations come from: large protest movements, military conquest, a great leader, or a dynamic entrepreneur who invents a whole new industry. And all those things are true. But I think we have underplayed another force, which is the desire to amuse ourselves. So many transformative ideas and movements came to the world initially through someone being interested in a phenomenon that seemed to be totally useless but was kind of interesting or delightful.

BR: Can you give an example of where something playful leads to a major technical innovation?

SJ: One of the big themes that runs through the book is the playful prehistory of the modern digital computer. I could have actually written an entire book about that, because there are so many ways in which the computer came out of play. If you asked the average relatively literate person on the street where computers come from, they would probably say it was to do with Alan Turing trying to crack the Enigma code in Bletchley as part of the war effort. But the first programmable machine we know about was a kind of flute-playing doll, created in Baghdad in the 6th century BC. Fast-forward a thousand years, and you have this great encounter, which was a crucially London encounter, where a young Charles Babbage visits a mechanical museum in Hanover Square filled with mini-automata, gambling machines, and music boxes. Babbage was particularly mesmerised by an automated dancer, a girl with a bird. Something about her captured his imagination and sent him off on this quest to investigate the possibilities of mechanical engineering, which ultimately led him to create the Difference Engine and the Analytical Engine, the first real programmable computers in history: so the computer comes from a mechanical flute player and an automated doll. And of course chess and other games have also played an important role in the history of the computer.

BR: You also write about shopping. Would you like to say a bit about that? It’s a very London story. You link that to the Industrial Revolution don’t you?

SJ: It’s an important story because it highlights the point that not all the outcomes of play-driven innovations are positive. I have been criticised for suggesting that play is a lovely thing that leads to other great things: actually, I believe play and delight are incredibly influential for good – but also for bad.

The conventional story we have of the Industrial Revolution is that it was driven almost exclusively by men who invented powerful weaving machines, and that that eventually created a consumer society, with department stores, a fashion industry and so forth.

But actually I think that story has it exactly backwards. What happens is that, starting in the middle of the 1500s, new cotton-based fabrics like calico and chintz arrive in London. Cotton has two great qualities. First, it is soft and sensual, particularly when worn as underwear – everyone was wearing wool until that point. Second, it comes in beautiful colours and patterns – and it could be washed again and again. During the 17th century, London importers and traders began to display their wares in a new sort of space, and basically, these were the first modern shops – spacious and welcoming and beautifully laid-out, with large windows and window displays – quite different from the market-type stalls where most things were sold. These shops were particularly popular with women. People went crazy for “calico”. As a result, the East India Company took off, becoming a massive importer of these fabrics; but that created a backlash, because it had devastating effects on the native English wool industry. People began criticising the cotton trade. You get something like a “make England’s wool industry great again” movement, and women in particular are singled out for criticism for buying all these imported textiles. They’re called Calico Madams and there are plays, poems and songs written about how these scandalous women are destroying the British economy. Calico was briefly banned.

In the next twist in the story, inventors and entrepreneurs began to search for ways of manufacturing cotton at home, and that was what really set the Industrial Revolution in motion. Almost all the major innovations at the beginning of this period come from trying to manufacture cotton textiles. And of course when Western cotton manufacture does take off, it comes to rely on the institution of slavery, especially in the South of the United States, which in turn causes the Civil War, and these things – slavery and the Civil War – were arguably the worst things to happen to the US. But the whole thing starts with women shopping in these new stores in London. So it wasn’t men inventing the loom that led to fashion and shopping, but fashion and shopping that led to the loom!

BR: What about pubs and cafes? You think they’re important in the story of innovation?

SJ: Taverns played a big role in the Roman Empire. But for me the story really gets interesting with the English pub, and the American pub during the Revolutionary period. The American Revolution is the best example of the power of the pub as an institution. Pubs or taverns are not utilitarian places – people meet in them to relax and drink and have social conversations – but in the American Colonies in the 18th century, they emerged as information and political hubs: news about the conflict with the King and the British government was distributed and discussed in taverns, and they were where groups of patriots came together. The American Revolution probably wouldn’t have happened had pubs not been invented – at least, it would have required a different information network, a different kind of space where people could get together to share information, discuss the issues of the day, and agree on action.

Pubs and bars have continued to play an important role in political history. Think about the importance of bars in the history of the gay rights movement. Bars became the first spaces where gay people came together in a way that was a least half-public, and that helped with their empowerment. Two bars in particular played a crucial role in the gay rights movement: The Stonewall Inn in the West Village, and The Black Cat in LA. Police raids on both places led to gay people coming out to protest their rights. We might think of bars as places to go and waste time but they have actually played a really important role in political life.

BR: You suggest that what we might call leisure spaces – what are sometimes called “third spaces” – have played a big part in economic innovation.

SJ: This is where we get to my favourite topic of all time – the coffee house and, especially, the London coffee house. From around 1660, coffee houses really took off in London, much more so than in any other city in Europe, and much of the British Enlightenment came out of these places. Magazines were basically invented in coffee houses, and so, of course, was the modern insurance business. Lloyds of London – the first proper insurance exchange – developed from a coffee house. And the first public museum – the British Museum – basically evolved out of a coffee house display of curiosities. And it goes on.

Inevitably, lots of moralists opposed coffee houses at the time and, in fact, Charles II tried to outlaw them on the grounds that they encouraged idleness and diverted his subjects from “their lawful calling and affairs”. It’s ironic, because people weren’t wasting their time at all. The coffee houses may have begun as places of leisure and pleasure but they transformed the economy.

BR: So do you think that city planners and city leaders should really treasure their third spaces? What sort of role do you think cafes and bars are playing today, and should we be worried about their loss?

SJ: Well, I think it’s changed a little bit in the sense that clearly we have more coffee houses than ever – but when you walk into your average Starbucks or Café Nero in London, do you feel it’s quite the same scene as it was in 1730? Are you seeing a new British Enlightenment in action? No. In the smartphone, social-media age, people are more likely to be sitting with their headphones in checking Twitter than engaging in face-to-face conversations.

For me, the heir to the coffee house is the co-working space – where you have a bunch of freelancers and startups, and a public common space where you can get coffee and meet, where people come in to give talks, and you have an events programme. The thing that made the 18th-century coffee house so great was its professional and intellectual diversity. The coffee houses weren’t focused in the way a modern business or academic department is. People came to drink coffee, and interesting collisions happened. I think we’re starting to see in the shared workspace model a 21st-century version of that.

I have mentioned the coffee house, but another space where London has been a pioneer is the park. At about the same time as the coffee houses were catching on, London began to develop its great parks, which offered a different sort of space for play, amusement and delight. I thought about this a lot during the Trump campaign. Trump kept describing our cities as these terrible places where people were shooting other people, which was so bizarre given that he’s a New Yorker and New York has never been safer.

I remember going to Prospect Park in Brooklyn, where we live, on the Fourth of July during the campaign, and seeing the unbelievable global parade of people from every country in the world, hanging out in what’s basically a place that is designed specifically for play. So there’s another example of the power of play – parks are places where people can come together as a public, despite all their differences, and that’s important in a democracy.

BR: I so agree. I always think that about the Tube, especially on a Saturday night. People of all ages and backgrounds are crammed together but, despite the crowds, for the most part, it goes well. People aren’t necessarily talking to each other but they are all making eye contact and making way for each other, and it’s a civilising force.

SJ: It’s extraordinary, and we need to remember that this sort of mixing is a very unusual achievement, in terms of history. And a lot of it happens in spaces dedicated to play and delight.