Tag Archives: Jane Jacobs

Make little plans

In Cities and the Wealth of Nations, Jane Jacobs quotes a Japanese economist about his country’s capitalist revolution following the Meiji Restoration. He said that the greatest periods of creativity and productivity had been experienced when the country was adrift, not focused on any particular goal but open to all opportunities.

Urban planners, particularly Americans, identify with the maxim “make no little plans” attributed to Chicago plan architect Daniel Burnham. According to this idea maximum effort should be focused on a single, enormous goal, and a concensus should be built around this goal in order to achieve it. This is how the Chicago plan was realized, and this has been the frame upon which nearly every urban plan continues to be modeled. New innovations, like the charette process, are only refinements of the paradigm established by Burnham. To someone focused on a single large-scale goal small-scale problems like a complicated permitting process or bad street design are irrelevant. Someone focused on a single large-scale goal does not see any drawbacks to using repression to realize the plan, like zoning and urban growth boundaries. The city they envision does not have a small scale, and this is now the reality of our landscape: urbanization at enormous scale, with no concern for details and no sustainability.

A creative city is not goal oriented. Not only does it make little plans, it makes millions of little plans. It is adrift looking for its next opportunity. It is not made by an architect, but cultivated by its people.

Make millions of little plans.

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The Journey to Emergence

This is part I of a series of excerpts of an article to be published in the International Journal of Architectural Research entitled The Principles of Emergent Urbanism. Additional parts will be posted on this blog with the editor’s permission until the complete article appears exclusively in the journal’s upcoming issue.

Of the different domains of design urban design is an oddity. While the design of a machine can be traced to a definite, deliberate act of invention, and even the design of buildings (architecture) is rooted in known production processes, the design of cities was never seriously attempted until well after cities had become a normal, ordinary aspect of civilized living, and while the design of machines and buildings was a conscious effort to solve a particular problem or set of problems, cities appeared in the landscape spontaneously and without conscious effort. This places the efficacy of urban design in doubt. The designers of machines and buildings know fully how the processes that realize their design operate, and this knowledge allows them to predictably conceive the form they are designing. Urban designers do not enjoy such a certainty.

How is it possible for what is obviously a human artifact to arise as if by an act of nature? The theory of a spontaneous order provides an explanation. According to Friedrich A. von Hayek (Hayek, 1973) a spontaneous order arises when multiple actors spontaneously adopt a set of actions that provides them with a competitive advantage, and this behavior creates a pattern that is self-sustaining, attracting more actors and growing the pattern. This takes place without any of the actors being conscious of the creation of this pattern at an individual level. The spontaneous order is a by-product of individuals acting in pursuit of some other end.

In this way cities appear as agglomerations of individually initiated buildings along natural paths of movement, which originally do not require any act of production as dirt paths suffice. As the construction of individual buildings continues the most intensely used natural paths of movement acquire an importance that makes them unbuildable and these paths eventually form the familiar “organic” pattern of streets seen in medieval cities. This process still takes place today in areas where government is weak or dysfunctional, notably in Africa where urban planning often consists of catching up to spontaneous settlement, and in the infamous squatter slums that have proliferated in the 20th century.

transect-of-tultepec

A transect of the city of Tultepec in Mexico provides a snapshot of the different phases of spontaneous urban growth. (Google Earth image)

As urbanization becomes denser, the increasing proximity of concurrent, competing individual interests causes conflicts between the inhabitants of the emerging town. Individuals build out their properties in such a way that it interferes with others, for example by blocking paths or views. These acts threaten the sustainability of the spontaneous order, and to resolve this situation the parties involved appeal to the same judges that rule on matters of justice. These judges, again according to Hayek, are required to restore and preserve the spontaneous order with their rulings. These rulings provide the first building regulations and, when government authority becomes powerful enough to do so, are compiled into comprehensive building codes to be applied wherever the force of that government extends. (Hakim, 2001)

The compiled building codes are later brought by colonists to create new settlements, reproducing the morphology across multiple towns but each time in a pattern that is adapted to the local context. Early town planning efforts are attempts at regularizing the building codes in order to plan for long-term organization of cities, but maintain the spontaneous production process. Most notably the rapid urbanization of New York City was accomplished by very simple rules on the size of blocks laid out in the 1811 Commissioners Plan for New York. Unlike the experience of urbanization in previous centuries, where urban growth was slow and often stagnant, the urbanization of New York took place in a time of rapid social and economic changes, and the city government had to invent building codes involving issues that never could arise in a pre-capitalist society: first the tenement, then the skyscraper, and ultimately, the automobile.

Modernism: the replacement for the spontaneous order

Architects and urban planners of the early 20th century, confident in the techniques of engineering and industrial production, believed that the spontaneous city had become irrational and had to be replaced with a new design fully integrating new industrial technology. The Swiss architect Le Corbusier is famous for designing a complete city around the automobile and building models of his design. In so doing he adopted a process of urbanization that was completely planned hierarchically, applying the processes familiar to architects at the scale of an entire city. He also ridiculed the morphology of spontaneous cities as being the product of donkey-paths.

villa-radieuse

This scale model of Le Corbusier’s Plan Voisin marks the turning point where city plans as constraints on individual initiative are replaced with architectural design at the scale of millions of inhabitants. (Le Corbusier, 1964)

Although the architectural program of high-rise living of Le Corbusier was discovered to be a colossal failure, the modernist process of development replaced spontaneous urbanization in the industrialized world. The housing subdivision substituted adequately for the high-rise tower block, providing affordable housing in large numbers to a war-impoverished society. This production process is still in force today, separating cities into three distinct zones: residential subdivisions, industrial and office parks, and commercial strips.

Modern city planning has been successful at its stated objective, producing a city designed specifically around automobile use, yet it was immediately and has been perpetually the target of criticisms. Most significantly the vocabulary of these criticisms had to be invented in order to spell out the critics’ thoughts because the type of deficiency they were observing had never been seen. Words like placeless or cookie-cutter were invoked but fell on the deaf ears of urban planners who were trained in Cartesian processes and industrial production techniques.

The most devastating criticism of modernist urban planning came in the form of a sociological study and personal defense of the spontaneous city, the book Death and Life of Great American Cities by Jane Jacobs. (Jacobs, 1961) In it she described in great details how the functions of a spontaneous city related and supported each other. Her concluding chapter, the kind of problem a city is, is still the most relevant. In it she attacks the scientific foundations of urban planning at a paradigmatic level, and claims that the methodology of the life sciences, at the time undergoing the revolution created by the discovery of DNA, is the correct approach to studying cities.

Death and Life of Great American Cities has been adopted by contemporary urban planners as a textbook for urbanity. Its descriptions of the characteristics of a city are now the models upon which new developments are planned. The old urban development of housing subdivisions and office parks is being substituted for the new urban development that has streets, blocks, and mixed uses, just as Jacobs had described to be characteristic of life in the city. A major difference between Jane Jacobs’ preferred city and the new urban plans remains. The layout of mixed uses is organized and planned in the same process as Le Corbusier planned his city designs. The scientific suggestions of Jacobs have been ignored.

The discovery of emergence and complexity science

In the time since Jacobs published her attack on planning science molecular biology has made great technological achievements and provided countless insights into the morphology of life. In parallel the computer revolution has transformed the technology of every human activity, including that of design. But the computer revolution brought along some paradigm-altering discoveries along with its powerful technology. In geometry, the sudden abundance of computing power made it possible for Benoit Mandelbrot to investigate recursive functions and his discovery, fractal geometry, generated a universe of patterns that occurred in many aspects of the physical universe as well as living organisms. (Mandelbrot, 1986)

Some thinkers saw that the life sciences were part of a much more general scientific domain. They formed the Santa Fe Institute and under the label complexity studied not only organisms but also groups of organisms, weather systems, abstract computational systems and social systems. This research formed a body of theory called complexity science that has resulted in the creation of similar research institutes in many other places, including some centers dedicated specifically to urban complexity.

Their scientific revolution culminated in two major treatises within the last decade, both from physicists practicing in a field of complexity. The first was A New Kind of Science by computer scientist and mathematician Stephen Wolfram (Wolfram, 2002), where he presents an alternative scientific method necessary to explore the type of processes that traditional science has failed to explain, presenting a theory of the universe as a computational rule system instead of a mathematical system. The second was The Nature of Order (Alexander, 2004) by architect Christopher Alexander, where he presents a theory of morphogenesis for both natural physical phenomena and human productions.

A definition of emergence

To define what is meant by emergence we will use the abstract computational system upon which Wolfram bases his theories, the cellular automaton. Each cell in a row is an actor, making a decision on its next action based on its state and the states of its direct neighbors (its context). All cells share the same rule set to determine how to do this, that is to say all cells will act the same way with the same context. In this way each row is the product of the actions of the cells in a previous row, forming a feedback loop. The patterns of these rows are not in themselves interesting, but when collected in a sequence and displayed as a two-dimensional matrix, they develop complex structures in this dimension.

rule30

The 30th rule of all possible rules of one-dimensional cellular automata produces a chaotic fractal when displayed as a two-dimensional matrix, but most other rules do not create complex two-dimensional structures. The first line of the matrix is a single cell that multiplies into three cells in the second line in accordance with the transformation rules pictured below the matrix. This process is reiterated for the change from the second to the third line, and so on. All the information necessary to create structures of this complexity is contained within the rules and the matrix-generating process. (Wolfram, 2002)

The same general principle underlies all other emergent processes. In a biological organism a single cell multiplies into exponentially greater number of cells that share the same DNA rules. These cells create structures in a higher dimension, tissues and organs, which form the entire organism. In the insect world complex nests such as termite colonies emerge from the instinctual behavior of individual termites. And in urbanization, buildings form into shopping streets, industrial quarters and residential neighborhoods, themselves overlapping into a single whole system, the city.

References

Alexander, Christopher (2004). ‘The Process of Creating Life’, The Nature of Order Vol. 2, Center for Environmental Structure
Corbusier, Le (1964). La Ville Radieuse. Éléments d’une doctrine d’urbanisme pour l’équipement de la civilisation machiniste, Édition Vincent Fréal et Cie, Paris, France
Hakim, Besim (2001). ‘Julian of Ascalon’s Treatise of Construction and Design Rules from Sixth-Century Palestine,’ Journal of the Society of Architectural Historian, vol. 60 no. 1
Hayek, Friedrich A. (1973). ‘Rules and Order’, Law, Legislation and Liberty Vol. 1, Routledge and Kegan Paul, London and Henley, UK
Jacobs, J. (1961). The Death and Life of Great American Cities, Random House and Vintage Books, New York, USA
Mandelbrot, Benoit (1986). The Fractal Geometry of Nature, W.H. Freeman, New York, USA
Wolfram, Stephen (2002). A New Kind of Science, Wolfram Media, USA

Fake Complexity – Mixed Used Development

The economic crash has cities scrambling to keep their real estate markets alive. Disappearing credit has caused many of the most capital-intensive projects, meaning big buildings, to halt. Some have been surprised that projects modeled on traditional patterns of urbanism, such as mixed-used developments, have been caught up in the storm. It’s one thing when a lone skyscraper or a subdivision at the edge the city stops dead in development. It’s simple to ignore and get around. But when an entire neighborhood of urban fabric disappears and leaves a large hole in the core of the city, the loss of urban life is noticeable. This is exactly what happened with mixed-used redevelopment in Salt Lake City.

For many, the Sugarhouse area was full of nostalgia. The downtown area featured local shops including a boutique, record store and a corner coffee shop that became a commons area for many residents. All this was lost when the developer Craig Mecham demolished the Granite Block of Sugarhouse for a new mixed-use project. The plans were to create a live-work-play dense pedestrian friendly environment for citizens.

“I actually think it’s a great idea because it’s going to bring housing to Sugar House,” said SLC resident Zach Moses. “There’s a lot of housing around Sugar House, but there’s not really any in it.”

But with America’s economy reaching its lowest numbers since the Great Depression, Mecham lost his funding and left a huge hole. Now city officials want Mecham to fill the hole, only to later dig it up again when he achieves the funding. This would result in an extra $80,000 added to the cost of the project.

http://www.utahstories.com/Sugar_House_Cottonwood_Mall_Redevelopment.htm

Mixed used development is the invention of a Frankenstein urbanism, where parts of living neighborhoods have been stitched together into an unnatural system and large amounts of money invested to shock the whole into getting up and looking alive. The stitches are nevertheless obvious, and the creature is moving a little bit funny.

When Jane Jacobs wrote Death and Life of Great American Cities, she described some qualities of cities that made neighborhoods alive. Some of them were small block sizes and mixed uses. What she couldn’t imagine at the time was how entrenched the municipality/developer growth relationship would become. And so municipalities, instead of returning to the creation of small blocks in their grids, continued making the superblocks but required the developers to build developments that matched the description of a neighborhood that Jacobs explained the workings of, without paying any notice to the process that created those neighborhoods she was describing. This not only perpetuated the unsustainability of sprawl, it also made the life of developers much more complicated.

Mixed-used neighborhoods work because they provide a marketplace for mixed people. Each person brings along his own specialized economic know-how, and so knows how best to provide in details the building program for his specific economic activity. A neighborhood, in that sense, becomes mixed-used because it is the product of mixed users all contributing their part to its complexity. What speculative mixed-used development does is force the developer to control and predict every building program in the neighborhood, then finance the entire development as one investment. The risk of failure is increased over single-use development, requiring subsidies either from the municipality or, as we saw in the case of Florida TNDs, the developer himself.

As older subdivisions and shopping malls become increasingly dysfunctional, the pressure to remove them whole is going to increase. But replacing them with another big development will not create the kind of neighborhood that disciples of Jacobs, or people who love the vitality of cities, wish to create. These neighborhoods are made by large numbers of people over time. We have to understand that suburban subdivisions are our context and that they must be preserved through the transformation into real neighborhoods for the simple reason that we can no longer afford to remove them. This requires creating a whole new kind of urban code and process. The codes for TNDs tell developers how to make urban-shaped development where nothing exists, but not how to repair the fabric of suburban sprawl through very small and random increments that improves the sprawl around them.

Mixed used development has been a mirage of sustainable development. It has allowed people to think that great historic cities can substitute sprawl development by changing the product, without changing anything about the production processes. (Ironically, Victor Gruen did something similar by recreating the european shopping street, within the suburban sprawl system, as the shopping mall. Shopping malls later become icons of sprawl.) With cities literally faced with gaping holes where wonderful drawings promised them urbanity, that mirage has been revealed to be a mound of sand.

This economic crash has been described as rivaling any crash since the 1930’s. This dates back before the creation of the municipality-developer system for urban growth. It’s possible that this time credit will not come back, and the system of big development cannot be resumed as it has worked in recent times. To recover from a crash as bad as the 1930’s, we may have to come back to development processes dating back before the 1930’s. Processes which rely less on massive concentrations of speculative credit and more on the piecemeal investments of regular people.

In the immediate time-frame, economic reality requires a massive down-scaling of the production of urban fabric. Those cities that first change the structure of their marketplace to restore the production processes for small development initiated by many people instead of a few developers will also be the first to get out of the slump, and emerge with mixed-used neighborhoods that are the product of the people who live there. If they cannot achieve that, then the next best thing is to create a more flexible regulatory framework that allows developers to create marketplaces for many people and to stop developing by big investments. This might save both the cities and their developers.

The movement economies

Bill Hillier of Space Syntax is, along with Christopher Alexander and Michael Batty, part of the British old school of urban complexity researchers. (Hillier has joked that he would have used the term “Pattern Language” instead of Space Syntax had Alexander not used it first.) He has studied the functional impact of spatial relationships on human behavior over a career spanning several decades, and came upon some very insightful results. The synthesis of his career was published last year in the book Space is the Machine, which you can read here.

Hillier presents a theory of urban emergence founded upon two ideas. First, that circulation in a city is determined by the configuration of lines into a global hierarchy of depth, which he calls integration. Second, that activities in the city adapt to take maximum advantage of this movement, a phenomenon he calls a “movement economy.”

How did he draw this conclusion? By observing that integration of lines could predict where all the major shopping streets in London are.

Which then is primary? Let us argue this through the spatial distribution of retail, the commonest non-residential land use. We may already have been suspected of having confused the effects of spatial configuration on movement with the effect of shops. Are not the shops the main attractors of movement? And do they not lie on the main integrators? This is of course true. But it does not undermine what is being said about the structure of the grid as the prime determinant of movement. On the contrary it makes the argument far more powerful. Both the shops and the people are found on main integrators, but the question is: why are the shops there? The presence of shops can attract people but they cannot change the integration value of a line, since this is purely a spatial measure of the position of the line in the grid. It can only be that the shops were selectively located on integrating lines, and this must be because they are the lines which naturally carry the most movement. So, far from explaining away the relation between grid structure and movement by pointing to the shops, we have explained the location
of the shops by pointing to the relation between grid and movement.
(SITM 125)

Once it has been demonstrated that it is the global network structure that determines where most of the movement will go, not any particular destination, then what remains to do is to exploit this movement. This is the movement economy. It is, in one sense or another, behind every act of urbanism, operating at every scale.

Every trip in an urban system has three elements: an origin, a destination, and the series of spaces that are passed through on the way from one to the other. We can think of passage through these spaces as the by-product of going from a to b. We already know that this byproduct, when taken at the aggregate level, is determined by the structure of the grid, even if the location of all the a’s and b’s is not.

Location in the grid therefore has a crucial effect. It either increases or diminishes the degree to which movement by-product is available as potential contact. As we saw in the coloured-up maps, this applies not only to individual lines, but to the groups of lines that make up local areas. Thus there will be more integrating and less integrating areas, depending on how the internal structure of the area is married into the larger-scale structure of the grid, and this will mean also areas with more by-product and areas with less.

Now if cities are, as they were always said to be, ‘mechanisms for generating contact’, then this means that some locations have more potential than others because they have more by-product and this will depend on the structure of the grid and how they relate to it. Such locations will therefore tend to have higher densities of development to take advantage of this, and higher densities will in turn have a multiplier effect. This will in turn attract new buildings and uses, to take advantage of the multiplier effect. It is this positive feedback loop built on a foundation of the relation between the grid structure and movement this gives rise to the urban buzz, which we prefer to be romantic or mystical about, but which arises from the co-incidence in certain locations of large numbers of different activities involving people going about their business in different ways. (SITM 126)

From this knowledge, we can arrive at a paradigmatic definition of urbanity. A space can be considered urban if it makes maximum economy of the movement that passes through it. A city, at any scale, will be qualified as a good city if the experience of movement is not felt as a burden but as an opportunity and pleasure.

A visitor from Canada once remarked to me that he had walked from the Eiffel tower to the Pantheon, a trip of more than 4 kilometers, without feeling the distance. This is something he could never have done back home, where inevitably one would run into long stretches of mind-numbing repetition or parking lots. Paris, on the other hand, offered him a path through the city that was rewarding his presence. Certainly the excellent late 19th-century residential architecture plays a role in creating a basic comfort level, but architecture alone does not distract for such a long distance.

Paris is known as a city of highly sophisticated urbanity, and this is attributable to the efficient movement economy that was seeded there during the Haussmannian period. The most integrated lines, the typical boulevards and avenues, have been constructed in such a way that they make maximum use of residual movement. And what may be most surprising, a revelation that the occasional tourist will miss out on, is that the least integrated lines, the common residential streets, are generally quite boring, bordering on unpleasant. They are rarely seen by anyone except their residents due to their spatial segregation. It is safe to say, then, that the “real” Paris, what makes the city worth visiting, are its highly integrated spaces.

How do these spaces realize movement economies? Firstly they provide multiple scales of movement as well as the interfaces between those scales of movement. The grand avenues centered on the Arc de Triomphe are in fact three different scales of movement: promenade, street and highway, connecting into each other. While someone crossing the city in an automobile would be exposed to all the activity taking place on the promenades, he could decide to pull over into the street section, curb-separated from the highway section, and park his car in an available spot, then walk to his chosen destination. While walking there, he encounters shops he could stop in if it occurred to him to make a purchase. Restaurants and fast-food outlets provide him with a convenient option for dining. On the street side, news kiosks offer him information and headlines. All of this benefits him and occupies his mind at no cost as he was already taking this path for other reasons.

While he is walking to his destination, people are sitting in sidewalk terraces drinking beer and coffee, watching him walk by. They are also taking advantage of movement. William H. Whyte, author of the classic The Social Life of Small Urban Spaces, observed that the primary activity that takes place in plazas is people-watching, people moving through that is. On the Avenue des Champs-Élysées, the most trafficked in the city, restaurants have outdoor dining rooms right between the highway and the pedestrian flow. They are highly prized, despite the noise and wind, because people enjoy watching the movement.

Since Alphand, the city of Paris has split promenades into three strips. The center strip is the open space through which pedestrians walk. The street-side strip is for street furniture such as kiosks, public washrooms, benches, bus stops, and so on. The building-side strip is for “concessionaires”, retailers and restaurants renting a part of the street to open their space to the exterior. The formula for a good promenade is that simple.

Needless to say, it takes quite a lot of movement to support so many mutually-dependent activities. But high-end avenues are not the only spaces that can take advantage of movement economies. Urban movement is fractal (it occurs at all scales). Hillier found that placing a limit on the range of movement, one obtained a local integration map that was different than the global integration map, and the movement in this locally integrated space was qualitatively different than global movement. These locally integrated paths develop local movement economies of their own. Typically, while highly integrated paths will become high-end shopping streets, locally integrated paths will be neighborhood service streets. Instead of trendy restaurants, fashion boutiques and cinemas, you find supermarkets, bakeries, post offices and cafes. And when we look at things with enough abstraction, we can see that even a shopping mall is a form of locally-integrated movement economy, where anchors terminate important axis and boutiques support each other by intercepting movement. Kiosks and cafes now take up even more space in the center of shopping mall promenades than they do in Parisian boulevards. It should be no surprise that people who live in suburban cities reflexively head to the mall for activity. Shopping malls, in the suburbs, have the most densely developed movement economies!

Besides creating commercial potential, movement economies also provide security. This is something that Jane Jacobs insisted on in Death and Life of Great American Cities through her concept of eyes on the street, but Hillier found an inverse statistical correlation between burglaries and spatial integration. What this brings us to is that there is a lower bound to urbanity, that we have defined as the realization of movement economies, where spaces lose integration and become segregated. If there is not enough movement, there is no purpose to public space. This is the point where public space becomes pathological, and where “defensible space” becomes necessary. Disastrous social housing projects have become the textbook case for failed public space, and their segregation explains their pathologies.

Parisian urbanism offers another excellent solution out of this problem. While the avenues are congested and noisy, full of life and activity, the lots are organized as courtyards from which several buildings are accessible. These courtyards are locked behind digitally-secured coach doors. It is rarely the case that one is invited to a dinner party without being given several “digicodes” to get through the secured, segregated spaces. Once in the courtyard, the noisy street becomes peaceful silence. These courtyards are functionally identical to the despised suburban cul-de-sac. But the cul-de-sac is not the problem, the streets they connect to are the problem. Paris balances two extremes, highly public, highly integrated space and completely private, gated space, side-by-side, supporting each other. Manhattan’s street-and-skyscraper urbanism is essentially the same, except that instead of going deep away from the street, one has to go up after entering segregated space.

New Urbanists in America and compact city advocates in Europe insist on having fully open grids, sometimes with alleys, instead of cul-de-sacs. There is nothing wrong with a cul-de-sac in itself; it is only a large residential building turned on its side. The important work is creating density in highly integrated lines. Arturo Soria y Mata invented the linear city in the 19th century as a utopia, but in reality, all cities are linear cities, functioning at fractal scales. The realization that the spatial integrity of the line is more important than anything that goes on behind the buildings occurred to me while taking a bus through the west Paris city of Nanterre, widely acknowledged to be a wasteland. The line the bus was taking was well composed, and I did not realize where I was until I caught a glimpse of wasteland Nanterre in a gap between two buildings. So far as anyone on that street was concerned, this didn’t affect them negatively. That is how resilient urban fabric can be.

Afterword

Local integration map of Central London

From Space is the Machine, global and local integration maps of Central London.

Self-organization of cities around natural movement is an important demonstration of complexity. Without anyone having willed or designed it that way, the aggregate actions of the millions of residents of London, all randomly travelling from one point to another of the network, resulted in the production of a fractal structure of the urban grid.

References

Bill Hillier. Space is the Machine
New Science. New Urbanism. New Architecture – Proceedings from a London conference, Katarxis.

Emerging the city

In the 20th century, the modern movement in architecture drew up grand plans to remake cities for the machine age. Le Corbusier, the leader of the movement, conceived his Radiant City plan. He designed every part of it himself so that it would work as he had willed it to. His machine provided the solution to four problems: inhabitation, work, recreation, circulation. Everything else was removed.

The idea of a machine city expressed three assumptions that led to the catastrophic results of modernism.

The first assumption is that the city is a machine that solves a problem. It can then be designed as a tool would be.

The second assumption is that the will of a designer can be imposed at the scale of a city.

The third assumption is that the form of a city, its morphology, can be conceived in advance of its development (“planned”).

After a titanic fight over the future of New York City, Jane Jacobs explained this error in the final chapter of Death and Life of Great American Cities. The “kind of problem a city is” shares nothing with the physical and engineering sciences. It is like the biological sciences, a problem of organized complexity.

The city does not solve a problem or some problems, it provides the environment to solve the infinite diversity of little problems that human beings have.

It is so complex that no single human can ever hope to understand it entirely.

Its morphology must be defined by its growth process as it adapts to changes in human needs and desires.

The city cannot have a designer. It cannot be built according to a description fine-tuned to perfection. This has become obvious to practically everyone, although urbanism in the english-speaking world is still tied down by the title “urban planner” in the face of all the evidence that planning makes no difference whatsoever. Still the practice of large scale zoning and site planning continues.

The problem was the absence of an alternative theory.

Today this theory exists. Research into DNA and cellular automata has shown how systems of transformations, as opposed to descriptions, create complexity in nature through emergence. Cells which multiply themselves and interact following simple sets of transformation rules produce forms of astonishing complexity.

A system of transformations is similar to a recipe. It is a list of actions that you must take, as compared to a descriptive system which gives you a picture of a finished object. Imagine trying to bake a chocolate cake with nothing but a picture. Now try again with no picture but a full recipe. By following the recipe, you will get a tasty cake no matter what mold or size of cake you made. If you make a mistake in the recipe, your cake will not succeed.

The definition of emergence is thus: it is a form obtained as a result of following certain processes. The opposite of emergence is design: it is a form conceived by a designer which will be used as a blueprint for its realization.

In emergence, form is the result. In design, form is the starting point.

The 21st century paradigm of urbanism is discovering and applying the right recipe, DNA, transformation set, to build a city, at any size, shape, or starting point, so that it will always work, always be adapted, and always be full of life.