To think about processes...

Vendors selling fresh vegetables in the market in Guanajuato, Mexico.

In the case of understanding cities, I think the most important habits of thought are these:
1. To think about processes;
2. To work inductively, reasoning from particulars to the general, rather than the reverse;
3. To seek for “unaverage” clues involving very small quantities, which reveal the way larger and more “average” quantities are operating.
— Jane Jacobs, The Death and Life of Great American Cities

In her last chapter of The Death and Life of Great American Cities, Jacobs summed up the previous arguments in the book by articulating a broader conception of “the kind of problem a city is.” It was an argument that we need a more relevant, clear and useful framework of thought for confronting our urban problems. Without it, we are doomed to repeat the same mistakes, and to make no progress — indeed, to compound our problems, as we have evidently done.

In essence, Jacobs observed that we were thinking about cities as the wrong kind of problem — a problem that we thought was amenable to silver bullets and command-and-control techniques, working solely from the top of the urban pyramid downward. This wrong-headed approach, while it could seem effective in the short run, could only result eventually in a slow stagnation and over-exploitation of essential resources, causing a cascading series of human and ecological casualties. The book, and especially the last chapter, proposed an entirely different kind of approach. It was far from libertarian — a misunderstanding that too often occurs in thinking about Jacobs — but rather, it was a different kind of strategic approach.

It was known that at the time of her writing the book that her editor Jacob Epstein was advocating that she should drop this last chapter, and that she should talk about the problem of race instead. That problem was of course an urgent urban issue at that time, and it certainly seemed natural to speak of it. But Jacobs knew that, outside of the context of this new framework of thought, racism and other urban ills could not be seen as they are — as symptoms of a deeper structural disorder, requiring a deeper understanding of the nature of the problem itself: the nature of cities themselves. This was what she referred to in the chapter’s title, “The kind of problem a city is.” It was necessary to begin here, and then one could take up other problems, like racism (as she did indeed in later books).

This is a point that is sometimes lost on some of Jacobs’ contemporary critics. They want her to march with them against the injustice of racism, or perhaps class separation, or perhaps ageism, or perhaps sexism, or perhaps homophobia, or perhaps…

We can begin to see the problem. However legitimate are our concerns, it is not enough to march, or shake our fists, or write treatises. (From ivory towers?) It is not enough to play “Whack-a-Mole” — that children’s game where new toy moles continuously pop up after we whack down old ones — with our urban problems. They often simply get worse, as indeed they have.

Nor is it enough to “design away our problems” (the top-down conceit of many designers). While there is certainly a place for top-down actions — and indeed, Jacobs described a number of them in the book — they must occur in the context of a well-formulated strategic approach to the structure of the city. And one must understand that kind of structure, and the problem it represents for those who want to modify it.

Just so, one must also understand the processes that occur in the city, since structure and process are two sides of the same coin. More accurately, structure shapes process, and process shapes structure — we cannot deal with one without dealing with the other. Unfortunately, too many designers deal too much with structure alone, and too many planners deal with process alone.

This issue also invokes the age-old debate between “top-down” and “bottom-up” — and it suggests that is a false duality. The City is a partly self-organizing system, in bottom-up fashion. It is not a deterministic structure, composed by designers as a kind of final ideal state. But that is not to say that there aren’t important actions we can take to catalyze and direct growth, much as gardeners shape the growth of their gardens. Like gardeners, we can build trellises (infrastructure), plant good seeds (plan types), fertilize and water (incentives), prune and weed (regulations, including targeted zoning), and apply complementary planting (targeted catalysts). In that sense, we could say that “the kind of problem a city is,” is one that is more like gardening than carpentry.

This is a fundamentally important point. It means that we should be less concerned with “command and control” on the one hand, or libertarian fantasies of automatic goodness flowing from deregulation on the other. We should instead be concerned with careful stewardship, applying regulation in a more agile and deft way. We should be concerned with design for self-organization — to facilitate, harness and direct it, rather than to replace it.

Jacobs began the last marvelous chapter of Death and Life with an appeal to the importance of understanding the nature of the problem we are dealing with:

Thinking has its strategies and tactics too, much as other forms of action have. Merely to think about cities and get somewhere, one of the main things to know is what kind of problem cities pose, for all problems cannot be thought about in the same way. Which avenues of thinking are apt to be useful and to help yield the truth depends not on how we might prefer to think about a subject, but rather on the inherent nature of the subject itself.

Jacobs proceeded with a discussion of the history of scientific thought and its relation to the ways in which we think about and act upon cities. She noted how modern science really took off, around the time of Newton, when it mastered so-called two-variable problems, like linking how many houses one has over here to how many stores one can have over there. Or in physics, the laws of motion, for example, are two-variable problems.

But in the early twentieth century, something interesting had begun to happen: through statistics and probability we learned to manage very large quantities, where large numbers of variables were interacting. The interesting discovery was that one could manage those phenomena as statistical averages, without knowing much at all about the actual interactions.

This statistical science translated into the phenomenal technological power of the industrial revolution of that period. Much of our industry and the prodigious output of 20th century modernity was rooted in these powerful new statistical methods. Jacobs pointed out that the early ideas of Le Corbusier and others, and the later ideas of planners — often to the present day — rely upon this strategy of managing large statistical populations.

In this sense, the progression in science from two-variable problems to problems of statistical populations was mirrored in the progression from the neatly ordered elements of, say, Haussmann and his Parisian boulevards relating speed and location, or of Ebenezer Howard and his Garden City plans relating city and country, through to the more statistically informed plans of Le Corbusier, implemented around the world by the likes of Robert Moses and many others.

In either case the problem of cities was seen as one of devising reductive engineering schemes, seeking to isolate smoothly-functioning, easily related mechanical parts, in place of “messy” organic conditions. This more formal approach to cities was seen as advancement and modernization. But in the former case it was two-variable engineering, and in the latter case the problem of cities was also seen as one of statistical mechanics operating on large numbers. The newer science was added to the old.

Meanwhile, however, the biological sciences had moved beyond the statistical world of so-called “disorganized complexity” and had begun to understand the phenomenon that Jacobs called “organized complexity” — the area in the middle, between simple two-variable problems on the one hand, and large numbers of loosely variables on the other. Biologically speaking, that is where the phenomenon of life occurs — where a few crucial elements or variables have a crucial interrelated structure, forming a dynamic interaction. Jacobs referred to their structure as being “interrelated into an organic whole.”

It turns out that the problems of the human environment are more like these problems of “organized complexity”. As Jacobs wrote,

…While city planning has thus mired itself in deep misunderstandings about the very nature of the problem with which it is dealing, the life sciences… have been providing some of the concepts that city planning needs... And so a growing number of people have begun, gradually, to think of cities as problems in organized complexity — organisms that are replete with unexamined, but obviously intricately interconnected, and surely understandable, relationships…

She pointed out how the planning and architecture professions were at that time — 1961 — mired in the old sciences and their inappropriate models for cities:

Today’s plans show little if any perceptible progress in comparison with plans devised a generation ago. In transportation, either regional or local, nothing is offered which was not already offered and popularized in 1938 in the General Motors diorama at the New York World’s Fair, and before that by Le Corbusier. In some respects, there is outright retrogression. None of today’s pallid imitations of Rockefeller Center is as good as the original, which was built a quarter of a century ago….

Then she summarized what she considered the lessons of organized complexity:

In the case of understanding cities, I think the most important habits of thought are these:
1. To think about processes;
2. To work inductively, reasoning from particulars to the general, rather than the reverse;
3. To seek for “unaverage” clues involving very small quantities, which reveal the way larger and more “average” quantities are operating.

She summed up the problem as follows:

As long as [we] cling to the unexamined assumptions that [we] are dealing with a problem in the physical sciences, city planning cannot possibly progress. Of course it stagnates. It lacks the first requisite for a body of practical and progressing thought: recognition of the kind of problem at issue. Lacking this, it has found the shortest distance to a dead end.

Since the book was written, the field of “complexity science” — a loose term for related developments in mathematics, network theory, biology, and other fields — has advanced a great deal, and deepened many of Jacobs’ original insights. These advances have also deepened the respect that many people have for Jacobs, and in particular, the remarkable prescience of the last chapter of Death and Life.

Most people are now at least generally familiar with “systems theory,” and with fractals, algorithms, strange attractors, network science, and the like. We now know a great deal more about these topics, and how they can help us to understand and manage a number of complex human processes. It may not be too much to say that scientific understanding is reaching a point of “consilience,” as the biologist E.O. Wilson (father of “biophilia”) has termed it.

In any case, Jacobs is now being considered seriously in a number of surprising places. One of them is the Santa Fe Institute for the Study of Complex Systems. Geoffrey West, past president, has said that in many ways, what they are doing today is “Jacobs with the math.”