It’s a beautiful day on Hampstead Heath, the last weekend of summer – parliament is still prorogued. In a festival tent at the HowtheLightGetsIn festival, Professor Shoshana Zuboff is talking about her recent book, The Age of Surveillance Capitalism: The Fight for a Human Future at the New Frontier of Power. Zuboff stands on a low stage, making eye-contact with her audience. She spies someone who seems unconvinced, invites them to raise their concerns. “When this book was published in January, I left home for three weeks on the road,” she says. “I’m still going.”

The audience laughs. Because The Age of Surveillance Capitalism – a 700-plus page sociological analysis of the digital era – has become an epoch-defining international bestseller, drawing comparisons to revolutionary works such as Rachel Carson’s Silent Spring. Naomi Klein has urged everyone to read it “as an act of digital self-defence”.

It describes how global tech companies such as Google and Facebook persuaded us to give up our privacy for the sake of convenience; how personal information (“data”) gathered by these companies has been used by others not only to predict our behaviour but also to influence and modify it; and how this has had disastrous consequences for democracy and freedom. This is the “surveillance capitalism” of the title, which Zuboff defines as a “new economic order” and “an expropriation of critical human rights that is best understood as a coup from above”.

Later, in an unglamorous spot by some parked vans, Zuboff explains why she wrote her book. She has dark eyes behind horn-rimmed glasses; abundant black curls; a low, resonant voice. She is brilliantly erudite and outlines her argument in trenchant, honed phrases, as if reading aloud. Her work on the themes of The Age of Surveillance Capitalism began as far back as the late 1970s. She was a postgraduate at Harvard, writing a doctorate on the Industrial Revolution. To earn money, she became an organisational change consultant, working in offices that were “computerising” for the first time. “They were expecting immediate productivity, growth, efficiency. But it was chaos, disaster. Crazy stuff was happening. People were saying ‘My work is floating in space!’”

In 1978, Zuboff was working at the Washington Post, with linotypists who were converting to cold type. “One day I had just finished the graveyard shift, and I wandered into the National Gallery of Art, where I saw these hulking, dirty, dark entities in the pit of a bright white amphitheatre.” It was the Voltri-Bolton series by David Smith – an American sculptor who in the 1960s created sculptures from old factory machinery and debris. “I realised then the process of computerisation would be the next industrial revolution, and it would change everything – including how we think, and feel and how we create meaning. I had a notebook, and I started writing. This has been the agenda for my intellectual life since then.”

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Voltri-Bolton X, and Voltri Bolton IX. Photograph: NYT

This led to Zuboff’s first book In the Age of the Smart Machine: The Future of Work and Power (1988) – a startlingly prophetic analysis of how information technology would transform working lives. Long before the emergence of the internet, Zuboff argued that everything that could be translated into information would be – exchanges, events, objects – and that data streams would be used wherever possible for surveillance and control. It was followed by The Support Economy: Why Corporations Are Failing Individuals and the Next Episode of Capitalism (2002), co-authored with her husband, James Maxmin, a former CEO of companies including Laura Ashley and a Distinguished Scholar at MIT, who died in 2016.

On the strength of her first book, Zuboff became one of the first tenured women at Harvard Business School. She later became one of the youngest professors to receive an endowed chair. With her husband, Zuboff went to live in rural Maine; they raised their children, farmed deer. In 2009, their home was struck by lightning and burned to the ground. The family escaped, but lost all their possessions - books, research materials, passports. “One odd thing: when the house burned, that old notebook from DC survived.” Not long after this, Zuboff began to write Surveillance Capitalism.

It is the story of the digital revolution, and how the early utopian prospects of the web darkened into “a rogue mutation of capitalism marked by concentrations of wealth, knowledge and power unprecedented in human history”. Gmail was launched in 2004; Google subsequently admitted that it has scanned private correspondence for personal information. In the same year, Facebook was founded, its business model also based on the capture of and access to personal information. The metaphor Zuboff uses is one of conquest: “With so little left that could be commodified, the last virgin territory was private human experience.” In 1986, 1% of the world’s information was digitised. In 2013, it was 98%.

Surveillance capitalists sell certainty to business customers who would like to know with certainty what we do

It is a movement founded on predictive algorithms, mathematical calculations of human behaviour. Surveillance capitalists “sell certainty to business customers who would like to know with certainty what we do. Targeted adverts, yes, but also businesses want to know whether to sell us a mortgage, insurance, what to charge us, do we drive safely? They want to know the maximum they can extract from us in an exchange. They want to know how we will behave in order to know how to best intervene in our behaviour.” The best way to make your predictions desirable to customers is to ensure they come true: “to tune and herd and shape and push us in the direction that creates the highest probability of their business success”. There’s no way “to dress this up as anything but behavioural modification”. In 2012 and 2013, Facebook conducted “massive-scale contagion experiments” to see if they could “affect real-world emotions and behaviour, in ways that bypassed user awareness”.

There are crux points in the lives of societies and individuals. A revelation in a gallery. A cataclysmic fire, and a salvaged notebook. Zuboff argues that we are now at one more crux point: “The age of surveillance capitalism is a titanic struggle between capital and each one of us. It is a direct intervention into free will, an assault on human autonomy.” It is the capture of our intimate personal details, even of our faces. “They have no right to my face, to take it when I walk down the street.”

Such violations threaten our freedom, Zuboff says. “When we think about free will, philosophers talk about closing the gap between present and future. We make ourselves a promise: I’ll do something with that future moment – go to a meeting, make a phone call. If we are treated as a mass of ‘users’, to be herded and coaxed, then this promise becomes meaningless. I am a distinctive human. I have an indelible crucible of power within me… I should decide if my face becomes data, my home, my car, my voice becomes data. It should be my choice.”

Born in New England in 1951, Zuboff is the daughter of a pharmacist and a homemaker. Her maternal grandfather, Max Miller, was a self-made entrepreneur, who invented the servomechanism for the vending machine. In her youth, she “did lots of growing up in Argentina, living on the Altiplano, with people who lived very simple lives”. She is passionate about the natural world; her analogies often invoke farming and the rural environment. The only time she pauses mid-sentence is when a magpie with iridescent blue feathers alights beside us. “What a beautiful bird!” Zuboff tells me that at the start of the Industrial Revolution persuading farmers to work in factories was like trying to get a deer to pull a plough. It was too incongruous, they wouldn’t do it. “Then after a while, the deer took the plough. There’s a brief window before social amnesia sets in.”

When I ask how deliberate this all was, if Mark Zuckerberg, Larry Page and Sergey Brin were just a bunch of happy tech-utopians who accidentally opened Pandora’s box, she smiles wryly. “This was world-historical wealth creation.” Surveillance capitalists have “many strategies to protect themselves from the law. Lobbying, political capture, other economic methods that we associate with cartelisation.” They have also claimed that the internet is a new reality with different protocols; “Larry Page has said how could Google follow any law that came into being before the internet? This is propaganda.” In her talk at the festival, Zuboff dismisses another proposition, that these are innovative companies that occasionally make mistakes. “Yes, like Google Nest [Google’s home security system]: ‘Oh we’re so sorry, we put a microphone in the Nest surveillance system and we forgot! We forgot to put it in the schematic.” (This story broke in February, and Google described its failure to put the microphone on tech specs as “an error”.)

I felt I was up against the clock of social amnesia, psychic numbing – people were losing their sense of astonishment

What about Zuckerberg’s claims that “privacy is no longer a social norm”, or the advice of Eric Schmidt (Google CEO, 2001-2011): “If you have something that you don’t want anyone to know, maybe you shouldn’t be doing it in the first place?” Zuboff has, of course, heard this line a thousand times. It has been repeated not only by surveillance capitalists, but also by governments advocating the mass surveillance of civilians. She is brisk in response: “I tell people, if you have nothing to hide then you are nothing. This isn’t about Hayekian individuality, libertarianism – it’s a historical process of individuation that has developed hand in hand with political freedom and democracy.” It’s also not Orwell, not Big Brother. “There’s no one coming to take anyone away to the Gulag. It doesn’t want to kill us. It just wants to move us in the direction of its predictions and get the data.” Although, “in China we see the attempt to annex these technologies to the repressive state”.

Some have also proposed that “choice architecture” – nudges and coaxes – can be societally beneficial, if used wisely. Proponents of this argument include Cass Sunstein and Richard Thaler (co-authors of Nudge: Improving Decisions About Health, Wealth, and Happiness). Zuboff disagrees vigorously. “Once you legitimate the ex-machina nudge it is intolerable. It is an act of power over the other – rather than educating or alerting. Nudging is paternalistic. Behavioural economists such as Thaler legitimated the nudge, empowered and increased the audacity of the surveillance capitalists. Thaler got the Nobel prize.”

Why does she care so much? “I gave up a lot of time to write this book, over many years,” she says. “I gave up time with my husband, my children. I gave up my health. Everything I had I gave, because I felt I was up against the clock of social amnesia, psychic numbing – people were losing their sense of astonishment.” Yes, she agrees that “Snowden made a huge contribution to waking people up. The tech companies were implicated.” Leaked documents showed the NSA collecting data from Yahoo, Google, Facebook and Microsoft. And the Cambridge Analytica scandal? “Carole Cadwalladr’s work is heroic. And Chris Wylie [the Cambridge Analytica whistleblower] revealed that every aspect of Cambridge Analytica’s operations was simply mimicking a day in the life of a surveillance capitalist.” Instead of behavioural modification for commercial ends, the ends become political? Voting instead of buying? “Democracy is on the ropes in the UK, US, many other countries. Not in small measure because of the operations of surveillance capitalism.”

Every time Zuboff speaks in public, she asks the audience: “What are the concerns that bring you here?” People call out words: privacy; dystopia; control; monopoly; manipulation; intrusion; exploitation; democracy; misinformation; fear; freedom; power; rebellion; slavery; resistance. Everywhere the words are virtually the same. What can be done? People object, but nothing happens. Doesn’t that lead to lassitude? “Regulation,” she says, firmly. “This is what the tech companies fear most. We say that markets that trade in human futures are illegal – like the slave trade was made illegal.” Then we design “programs as a closed loop” and “reclaim the idea that we can have the digital without surveillance capitalism”. This will require the “indignation” of citizens, journalists, scholars and law-makers. “Surveillance capitalism has had 20 years unimpeded by law. But it is very young.”

The following day Zuboff is to give another speech, asking another audience: “What are the concerns that bring you here?” like a reclaimed version of that old Facebook question: “What’s on your mind?”

Zuboff has now been on the road for nine months. The alternative, doing nothing and being “subsumed in unadulterated power” is not an option for her. “We are not simply users. We are much used. We have to awaken to our shared future.”

• The Age of Surveillance Capitalism is published by Profile (£10.99). To order a copy go to guardianbookshop.com or call 020-3176 3837. Free UK p&p over £15, online orders only. Phone orders min. p&p of £1.99.