This article is a preview from the Autumn 2015 edition of New Humanist. You can find out more and subscribe here.

In 2007, the UN announced that, for the first time in the history of humanity, more than half the world’s population were now living in cities. After this milestone, the expectation is that by 2050 70 per cent of the world will be urban. This massive transition is largely being driven by the urbanisation of China, itself described as the largest migration in human history, as many millions of people leave their villages to seek work in giant new cities. It is expected that, after China and India, the same process will occur in developing African nations, leaving an almost completely urbanised planet by the end of the 21st century.

But what does this mean? We all know a city when we see one, but properly defining it is difficult. Max Weber argued that the presence of a permanent market was what set cities apart, while Lewis Mumford saw its origins in ceremonial shrines and burial practices. What is essentially clear is that a city is a settlement with highly concentrated populations, physical infrastructure and social organisation. But while the city is one of the defining creations of humanity, it has only existed for around 5,000 years, a relatively recent development in the history of our world. Cities may seem immutable, timeless, but their historical development has been rapid, awe-inspiring and often terrible. They have been the necessary condition for many of the cultures that define us as humans, offering unprecedented forms of freedom and power, but cities have ground down and destroyed countless lives over the course of their development.

In the years to come, the ways in which cities develop are going to be pivotal for the future of humanity on this planet. Threats such as accumulated waste, resource scarcity, food supplies, extreme weather, water shortages, energy insecurity, mass migration and social inequality, all inextricably linked to the dynamics of how cities function, pose grave threats to the continued existence of human society. The city will be one of the crucial links that could make or break civilisation, and much will depend upon whether its forces, both material and social, can be controlled and guided away from their most destructive tendencies. The question is: are cities there to serve human life, or is the city a force in itself, subject to its own laws and eternally reproduced by the humans who are drawn into it?

Cities are the products of immense amounts of labour, accumulated over many lifetimes, but the question of how their development occurs, who controls it and who benefits from it, has always been a vexed one. At different times, different types of power have existed in the city and different parts of society have been its main beneficiaries, from monarchies to priestly castes, landowners to technocrats.

Currently, we hear much discussion of the question “who is the city for?” In the UK, the housing crisis has become ever more acute, with prices rising 10 per cent in a year in the south east, while elsewhere in the country whole streets stand empty. Austerity has been tearing down supports that kept the rich and poor closely tied together, with the prospect of greater dispersal and segregation to come. It feels that more than ever the city is only for those who can afford to buy it.

This is a situation echoed across the world. On the one hand, there is the ascendant class of the global super-rich, collecting property in desirable spots across the globe, treating cities as safe deposit boxes with steak restaurants attached, nomadic, mobile, from everywhere and attached to nowhere in particular. At the other end of the scale are the global poor, frequently slum dwellers, stitched on to the edges of metropolises in super-dense settlements that have only the barest of connections to the city whose territory they share.

Defenders of these developments like to point to the vast improvement in the lives of those who are currently rushing into the cities in China, and indeed, today and throughout history, the transition from rural subsistence to urban work has been one of greatly heightened opportunity. But while the Chinese Communist Party make their gamble that the increased prosperity of their population will guarantee their legitimacy, in the developed world what were once called the working classes are seeing the gap between their lives and those of the rich grow ever wider apart.

There have always been these tensions between civic elites and those crammed uncomfortably into its boundaries. The city creates the possibility for groups of people to see themselves as politically bound together, with the density of human coexistence leading to the constitution of “the masses” or, put differently, “the public”. From the very beginning the city has been compelled to accommodate friction between the powerful and those they rule, the physical proximity of the latter creating the opportunity for them to organise through guilds and unions, or through violence and riot.

But is this relationship now hopelessly out of kilter? The level to which the buildings and infrastructure of developed cities are now financialised is unprecedented. Across the world many states have retreated from their role in the provision of housing, with the result that those most in need are neglected in favour of market-led provisions. But it’s not just housing: all manner of urban space that was once public has been transferred into private ownership, often invisibly. Journalist and academic Anna Minton’s celebrated work draws attention to the widespread transfer of public land into private hands, where freedom of access or assembly is revocable without reason or justification.

In recent decades, the ideas of urban guru Richard Florida held sway over governments and planning departments across the world. In books such as The Rise of the Creative Class, Florida explained that the secret of the resurrection of urban areas that had suffered generations of industrial decline was the encouragement and attraction of artists and web designers, whose lust for inner-city life would foster civic regeneration – and eventually economic revival too.

Florida’s ideas were massively influential, but not necessarily in the way he intended – “regeneration” too often meant simply “gentrification”. The replacement of more old-fashioned markers of local civic life, such as small shops and community centres, with the accoutrements of a wealthier class – the bicycles, flat-whites and estate agents – is sometimes decried as the cause of social tensions in urban environments. In fact these are secondary effects of larger, worldwide processes: the gradual liquidation of property from lump assets into complex financial instruments – and the instability that this has inevitably caused.

But it is not simply financialisation that is driving the development of today’s cities. Urbanist Keller Easterling believes that the combined effects of systems that are almost invisible, such as logistical dynamics, favourable regulation zones created to entice business and residents, are creating what she calls “infrastructure space”.

Easterling points to transnational business parks, “free zones” and other kinds of space created by the shaping tendencies of global infrastructure as the best vision of the future of cities: increasingly generic, perfectly manicured zones of exemption, frequently set beyond the control, both spatial and legal, of the individual nation states in which they might be found.

There is no reason to think that the intensification of infrastructural space is going to slow down any time soon. Indeed, the city is likely to become ever more networked. The intensified connectivity that began with the new modes of transport and communication of the mid-19th century, the railway and the telegram, has brought us to the point where not only are cities around the world within easy physical reach as never before, but the communities that constitute them are, harking back to Marshall McLuhan’s “global village”, in electronic proximity that transcends spatial distance.

The much-vaunted “Internet of Things”, in which homes, buildings and all the appliances within become totally networked, fully embedded into digital supply chains, promises all kinds of benefits, efficiencies of supply and demand, the reduction of waste in the production of goods and the freeing up of time for the inhabitants, as everything goes about its work with the greatest of ease.

But this ultra-networked world is also a world where your location is known at all times, where everything you do leaves an indelible trail, where those who hold power are tantalisingly close at all times to a complete set of information about the lives of their subjects. This networked city holds the promise of both unprecedented freedom and unprecedented control.

Everything may change, civilisations come and go, but this underlying tension between order and chaos, control and freedom, has been the driving dynamic throughout the history of the city, from the earliest pottery fragments to the present-day megalopolis.

Human remains indicating permanent settlements have been found in central Europe that date back 30,000 years, but it is not until the beginnings of agriculture, and, more importantly, the creation of a surplus, that the city begins to become what we know it as today. Once newly sedentary communities in the ancient Near East began to have some spare food left over after the harvest, it was possible for the inhabitants to have time and energy to diversify their activities. This led to the appearance of specialised labour, which in turn developed new technologies that improved agriculture further.

Soon after this feedback loop took hold, almost all the parameters of the city were in place – along with the new technology of writing, the city intensified the productive forces of humanity and sent us hurtling towards modernity. Large temples, palaces and other monumental buildings began to take up space as civic elites were sustained by the surplus of others’ labour.

Then, as since, however, the fantastic benefits of the city brought their own problems. The high numbers of people pushed together meant that the city has always been a dangerous place to be, requiring a more sophisticated form of social order to avoid chaos. This proximity also created the conditions for plague, bringing together reservoirs of potential hosts for viruses and bacteria. From the very outset, the city has been associated with dirt and pestilence – and pandemics remain a threat looming over our vast and interlinked metropolises to this day.

Furthermore, the large fixed community presented a form of opportunity for theft and conquest that had never before been available to hunter-gatherers, and from the outset the city was a conspicuous and enticing target. The development of military technology, both offensive and defensive, has been a major constraint on the development of cities. The thick walls of a raised fort were useful for thousands of years, when cities could hold out under siege for years at a time, but the invention of gunpowder caused a revolution in the design of city defences. In the 16th and 17th centuries, ever more complicated designs, such as those of the French engineer Vauban, created geometric ramparts that were almost beautiful, but often threatened to strangle the life of the city within their vast earthworks. Later, another revolution in warfare led to aerial attack and the nuclear bomb, rendering city defences obsolete.

For much of its life, the city grew according to various plans, whether those of the despot or the priestly caste, but maintaining control was intensely difficult to achieve. Time and again English monarchs attempted to halt the spread of London, but were unable to effectively impose their will upon the forces of growth that were in motion.

In and around the 16th century, the city began to be considered something that could be physically moulded, upon which a greater order could be imposed. With the Renaissance in Europe came a belief that the buildings of the city could represent the ideals of virtuous governance and justice, rather than simply the power of religion and monarchy. With this came the belief that it was possible to redesign the city entirely to create a proper setting for human activities, and the ideal city, a concept that haunts society to this day, came to life.

The Renaissance notion that cities should be laid out around a series of monumental civic buildings and spaces held sway for a long time, but would be tested up to and beyond its limits by the forces of the industrial revolution. The technological advances and the rush of the first mass urbanisation meant that millions of people flooded into the cities to work in the factories, and were packed into slums the like of which had never been seen before. Industrial capitalism, in drawing these people into the city and alienating them from their previous existence, had created a new class of humanity: the urban proletariat.

It was at this point, in the middle of the 19th century, that the image of the city as an infernal machine that ground up humanity took charge. The industrialised city was advanced as never before, but depraved as never before, bringing some of its inhabitants unprecedented wealth and others unprecedented misery.

Social reformers believed it essential that cities should be planned and controlled, but it took almost another century for the planned city to become a reality. The ruins created by the Second World War provided the opportunity and the imperative for governments across the globe – and across the ideological divide – to take charge of the forces of urban development. Planners and architects rose to the challenge, and as new cities rose up out of the plains of Siberia and Buckinghamshire, and the dilapidated encrustations of the recent past were cleared for modern housing and office blocks, there was a belief that technological modernity, used rationally, might have tamed the forces that had led humanity almost to the end of civilisation.

This post war optimism with regard to the city, a consensus that now appears to have been a peak of human attempts to make societies more equal and just, didn’t hold for long. By the late 1960s, the belief in urban progress through planning and technology was being challenged from all directions. The New Left and the ’68 generation saw the bureaucratic control of architecture and space as oppressive: Henri Lefebvre wrote of “the right to the city”, the idea that, against capitalist development and bureaucratic control, the inhabitants of a city have a common interest and a common right over its development and its processes of change.

From another direction, Jane Jacobs wrote in the 1960s of how there was no way that the top-down approach of governments making and executing plans could ever work with the delicate and finely balanced interactions and activities that made up city life. Jacobs was a veteran of the battles that regularly raged between local communities and the seemingly unaccountable forces that made decisions about the city they lived in, but her ideas about the essentially self-regulating character of urban environments fell neatly in line behind the turn towards economic ­neoliberalism that came towards the end of the century.

Today, cities in the developed world owe much to this strange mix of the anarchic distrust of top-down solutions and the vested interests of the development industry. Planning laws continue to exist, but are under constant attack as a malevolent force that prevents a solution to the various housing crises. Meanwhile, despotic monarchies in the Gulf and the Communist Party in China build brand-new cities for millions, based as much upon the barely planned American model of intensely motorised sprawl as anything else.

So what can we expect to happen to the city in the future? Can the urban situation be brought into order or is it at risk of running completely out of control? On the one hand, things do not look promising. If current trends continue, such as increasing inequality, inaction on climate change or the refusal to deal with resulting migration crises, then the future of the city could be bleaker than ever. Coastal cities vulnerable to sea-level rise, or those in parts of the world whose climate is especially vulnerable, could end up being abandoned, sending potentially billions of people in search of new places to live. The resulting stress upon space and resources looks guaranteed to cause more conflict, and we can see fortress-like attitudes hardening already today.

It’s not inconceivable that the city of the future, for the remaining sliver of the world’s rich, will begin to resemble a throwback to the baroque fortresses of the past. Technologically it is likely to be ultra-sophisticated, with the full range of zero-carbon energy, “smart” infrastructure and all the social benefits of a welfare state, but it will be a place to which access is desperately restricted, by both political and newly solidified physical barriers.

Of course, this may sound familiar because this is what already exists for much of the world’s population. This nightmare scenario is essentially the city of today, a Rio de Janeiro or Mumbai, with its contradictions intensified to the most extreme degree, a utopia for the select few who are allowed inside the walls.

But what does a more hopeful view of the future of cities look like? Cities were born out of humans abstracting natural processes to their advantage, but the next stage of human survival will have to involve cities drastically reducing their impact. An optimist will say that there are tantalising hints of an energy revolution occurring, with the costs of renewables and their storage looking set to drop to the point where they render hydrocarbon power obsolete. This development may not come in time to prevent devastating climate change, but it may make the cities that are left more able to support their populations well into the future.

Over the years, at least since Ebenezer Howard’s garden cities at the turn of the 20th century, images of the city reconciled with nature have been a major theme in visions of the urban future. If the forces of nature and technology were locked in a dialectic, then the dream was that a synthesis of industrial society and the natural world could be found.

This thinking peaked at the end of the 1960s, when the first wave of environmentalism hit a swell of technocratic optimism, and the public imagination was caught by visions of bucolic high-technology cities, sometimes held under giant bubble-like roofs, overgrown with greenery like a form of futuristic ruin. Many imagined that the settlements of the near future would be advanced cities of great public affluence, akin to the universities then being laid out across rural landscapes – modern, democratic, open and verdant. However, these brief dreams were largely shattered by the social and economic crises of the 1970s.

The city has always been a kind of bubble, where forces interacting caused inflations and effects that could not have happened in a less concentrated environment. The attraction of urban life has always been that more things can happen there than in a life spent outside. But cities have also been bubbles in the protective sense as well: where humans have come together to seek protection from the hostile world outside, whether that be rural poverty, indentured servitude, military threat or environmental degradation. Looking back, the city is and always has been a wonderful, intensely horrible place; whatever happens in the future, whether it’s green utopia or post-apocalyptic wasteland, or a messy mixture of both, the forces that shape the city are unlikely to be changing any time soon.

Douglas Murphy's latest book is Last Futures: Nature, Technology, and the End of Architecture