If only for a moment, set aside the comparatively parochial drama of Brexit, think about the giant swath of humanity that now uses the internet, and consider one of the most basic facets of how 4 billion of us live our lives. This is a 21st-century story, but it will ring bells with people old enough to remember the cold war: how people understand their own experience and events in the wider world is increasingly decided by the version of the internet they use.

On one side sits the system used in China, which produces vast amounts of personal data and blurs into a huge apparatus of state surveillance and censorship. This model is centred on two online behemoths, whose dominance partly comes down to the fact that Chinese consumerism is all about paying via your smartphone, rather than an old-fashioned plastic card. There’s the e-commerce conglomerate Alibaba, and Tencent, which owns WeChat, the platform used by more than 1 billion people every day. It does so many things – payments, social networking, messaging, travel booking, gaming – that participating in society without it seems all but impossible.

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On the other side of the modern digital divide is the version of the internet pioneered in the west and now spreading around the planet, which revolves around Google and Facebook. These giants also feast on a mountain of personal information, but present themselves as a contrasting embodiment of personal freedom and liberal values, even as they embed the social model now known as surveillance capitalism.

One of the central questions of our age is which model will become pre-eminent, not least among the half of humanity who are not yet online. With Donald Trump’s trade war providing a crude kind of mood music, the battle so far is not quite as simple as Chinese platforms duking it out with their US counterparts: the tech clash has been more visible in tensions over nuts-and-bolts infrastructure, particularly when it comes to the activities of the IT giant Huawei.

But look at high levels of tech investment by China in India and Africa, the prospect of Alibaba butting heads with Amazon, or the international competition between Uber and its Chinese equivalent Didi, and you get a flavour of the future – particularly when it comes to China’s mastery of mobile payment systems, which leaves most western countries standing. Across the world, geopolitics is fast boiling down to whether China or the US is the most influential tech player.

Meanwhile, the dominance of life in the west by corporations based in the US is being contested as never before. The Democratic presidential hopeful Elizabeth Warren says she wants Facebook, Google and Amazon to be broken up. The same sentiments are rising among more switched-on elements in Congress. As evidenced by the so-called right to be forgotten, the General Data Protection Regulation (GDPR), and such actions as the €1.5bn fine the European commission imposed last week on Google (for forcing customers to agree not to accept adverts from other search engines), the EU is much further ahead. If our current stereotype of legislators and regulators boils down to grey-haired men who barely understand how to switch their phones on, that is clearly changing fast.

The new cold war and the race to regulate are the contexts in which we have to understand everything that western big tech now does – something that applies particularly to the Facebook founder and CEO, Mark Zuckerberg. Ten years ago, he professed to believe in an ideal he called “radical transparency”, and “the concept that the world will be better if you share more”.

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Now, panicked by his company’s seemingly endless fall from grace, he says he is pursuing “a privacy-based vision for social networking”. Logically, the two ideas cancel each other out, revealing something much more prosaic: the sense that he is desperately trying to escape the clutches of his potential regulators, so that Facebook remains at the core of the western internet, ready to be endlessly pushed into new global markets.

Just over two weeks ago Zuckerberg put up a long post that announced his intention to develop a “privacy-focused communications platform [that] will become even more important than today’s open platforms”, based on message encryption, and the idea – copied from Snapchat – of content deleting itself, so as not to come back to haunt the people who post it. But what actually matters is that he wants to combine the messaging services offered by Facebook, Instagram and WhatsApp, which will surely make any attempt to break these entities up all the more difficult.

For the foreseeable future, old-style Facebook will carry on. Meanwhile, on their new platform, Zuckerberg and his colleagues are likely to still amass huge amounts of metadata (who we talk to and for how long, and where we are), while encryption takes the heat off their company’s absurdly overburdened moderators: as and when its users foment unrest and abuse, Facebook’s high-ups will be able to deny any agency, and stand well back. But most eye-watering of all is the sheer reach of Zuckerberg’s new creation: his plan is to “make it as secure as possible, and then build more ways for people to interact on top of that, including calls, video chats … businesses, payments, commerce, and ultimately a platform for many other kinds of private services”.

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This is precisely the WeChat model of an app that does just about everything, including handling everyday personal finance, thereby ensuring an endless avalanche of data. What that highlights is not just the scale of Facebook’s undimmed ambitions and Zuckerberg’s questionable new embrace of “privacy”, but something that attracts surprisingly little attention: the sense that even as the eastern and western models of the internet compete for global influence, they are converging.

Perhaps we should not be that surprised. At the height of the cold war, for all their mutual animosity, it was fashionable to talk about the US and Soviet Union as increasingly similar societies, subject to what the social theorist Herbert Marcuse called “common requirements of industrialisation”, and both in thrall to bureaucracy and centralised planning. In the wake of the revolutions of 1989 the basic idea flipped, so that east and west were said to be heading into a shared future of liberal democracy and free markets, a vision also projected on to an increasingly prosperous China, until the arrival of President Xi Jinping heralded something much more problematic.

Now convergence is here again, but this time it is all about surveillance, behavioural nudging, and companies so huge that they intrude on every part of our lives. The danger is the world falling between two visions that are too close for comfort: on the one hand, surveillance and censorship perpetrated by companies in brazen cahoots with authoritarian states; on the other, all-seeing tech corporations whose ties to government remain shadowy and opaque, which is part of what Edward Snowden came forward to tell us.

Legislators, regulators, developers and entrepreneurs should take note: if 21st-century democracy and the most basic ideas of citizenship are to mean anything, the western internet ought not to be converging with China’s, but pulling in the opposite direction.

• John Harris is a Guardian columnist