© 2013 Diana

Space Syntax: The fundamental city

From “Space is the Machine”, pg 262-267


Cities as things made of space

In the previous chapter it was suggested that the relation between human beings and space was, at a deep level, governed by two kinds of law: laws of spatial emergence, by which the larger-scale configurational properties of space followed as a necessary consequence from different kinds of local physical intervention; and laws of ‘generic function’, by which constraints were placed on space by the most generic aspects of human activity, such as the simple facts of occupying space and moving between spaces. In this chapter we argue that, to a significant extent, the spatial forms of cities are expressions of these laws, and that if we wish to understand them we must learn to see them as ‘things made of space’, governed by spatial laws whose effects but not whose nature can be guided by human agency. One implication of this argument will be that twentieth-century design (as dicussed in Chapter 5) has often used spatial concepts for urban and housing areas which fall outside the scope of these laws, creating space which lacks the elementary patterning which these laws have normally imposed, in some shape or form, in the past. If, as is argued here, such laws exist, then it will be necessary to revise current concepts of the well-ordered city back in the direction implied by these laws.

There are, however, obvious objections to the idea that urban forms evolve according to general laws. The most obvious is that cities are individuals, and that this is because the forms they take are influenced by factors which are quite specific to the time and place in which they grow — local topographical facts such as harbours, rivers and hills, particular historical events such as trading developments, population movements and conquests and by pre-existing contextual conditions, such as route intersections and the existence of exploitable resources. Each type of influence might be expected to have generically similar effects on urban form, but taken together it is highly unlikely that any two cities would repeat the same grouping or sequencing of influences. These factors, then, in spite of initially suggesting bases for comparison, tend make each city unique. And this, of course, is how we experience them.

A second objection is slightly less obvious, and a little contradictory to the first, since it is typological. The spatial and physical development of cities is — quite properly — held to be a reflection of the social and economic processes which provide the reasons for their existence. Differences in these processes are likely to give rise to differences in type between cities. We saw a clear instance of this in the typological contrast drawn in Chapter 6 between cities of production and cities of social reproduction. Differences in spatial and physical form were there shown to be reflections of differences in the essential functions of those cities. Similarly, differences in the physical and spatial form of cities, say, to the north and south of the Mediterranean, are manifestly connected in some way to the social and cultural idiosyncrasies of the European and Islamic traditions. It seems then to be specific social, economic and cultural processes, rather than generic spatial laws, that are the driving forces on urban form.

Both objections seem well-founded. Seen in one way, cities are individuals; seen in another another, they seem to be types. How can these facts be reconciled to the idea that general spatial laws might play a role in their spatial evolution? In fact, there is no incompatibility. It is simply a matter of the level at which we are talking. The influence of spatial laws on cities operates not at the level of the individuality of the city, nor on the typology of the city, but at the deeper level of what all individual cities and types of city have in common, that is, what, spatially, makes a city a city. As settlements evolve under different social and topographical conditions, they tend to conserve, in spite of the influence of these differences, certain properties of spatial configuration ‘nearly invariant’. By ‘nearly invariant’, we simply mean that the configurational properties we find fall within a very narrow band of combinatorial possibility. Without knowledge of these ‘near invariants’ we cannot easily understand what cities are in principle, before we consider them as types or as individuals.

What are these ‘near invariants’? Let us begin by looking at a pair of illustrative axial maps: plate 2c-e, which is part of London as it is now, and plate 7, which is the central part of Shiraz, in Iran, as it was prior to twentieth-century modernisation. The grids have clear differences in character. Line structures are more complex in Shiraz, and are in fact much less integrated and intelligible. If we were to examine the relation of lines to convex elements, we would find that in London lines tend to pass through more convex spaces that in Shiraz. Looking at the integration core structures, we also find differences. Although at radius-n (not shown in the case of Shiraz), both have strongly centralised cores, linking centre towards edge, at radius-radius, London has a ‘covering’ core, linking centre to edge in the way characteristic of European cities, while in Shiraz the radius-radius core is markedly regionalised. These differences in grid structure are associated with well-known behavioural differences, for example, in the ways in which inhabitants relate to strangers and men to women in Islamic as compared to European cities. We can call these associations of urban forms and social behaviour ‘spatial cultures’, and note that one of the main tasks of a theory of urban form would be to explicate them.

However, as can be seen from the two plates, underlying the manifest spatial differences we also find much common ground in the urban grids. For example, in both cases, the spaces formed by the buildings tend to be improbably linearised in at least three senses. At the smallest scale, we find that buildings are placed next to and opposite each other to form spaces which stress linearity rather than, for example, enclosure. Second, at a slightly less local level, lines of sight and access through the spaces formed by buildings tend to become extended into other spaces to a degree that is unlikely to have occurred by chance. Third, we find that some, but only some, of the linear spaces are prioritised to form larger scale linear continuities in the urban grids, creating a more global movement potential. These properties are present in the two cases to different degrees, but they are nevertheless present in both cases. They will be found to be present in some degree in most settlements.

At a more global scale, we also find commonalities across the two cases, which are also ‘near invariants’ in settlements in general. Two of the most notable are that in both cases we will find a well formed local area structure of some kind coexisting with a strong global structure. Both levels of structure are different in the two cases, but each case does have both levels of structure, and this we will find is generally the case in cities. At the most general level of the overall shape of cities, we also find ‘near invariants’. One of the most significant is that cities, as they grow, tend to fill out in all directions to form more or less compact shapes, even in cases where they are linear in the early stages. The ‘deformed grid’, with all the properties we have just described, seems to be the aptest term to summarise these, and other, ‘near invariants’ of cities, because, however much urban space is articulated and broken up, buildings are still in general aggregated into outwards facing islands to define intersecting rings of space, which then become improbably linearised to give rise to the local area and global structures that are found by configurational analysis.

These commonalities, it will be argued, arise from what spatial cultures have in common, that is, from what in the previous chapter was called generic function. This, it will be recalled, referred not to the different activities that people carry out in space, but to aspects of human occupancy of space that are prior to any of these: that to occupy space means to be aware of the relationships of a space to others, that to occupy a spatial complex means to move about in it, and to move about depends on being able to retain an intelligible picture of the complex.

Intelligibility and functionality, defined as formal properties of spatial complexes, are the keys to ‘generic function’. In the case of settlements, generic function refers not to the specificities of different cultural, social and economic forms, but to what these forms have in common when seen from a spatial point of view. The deep invariant structure of urban grids is generated, it will be argued, from generic function creating emergent invariants, while the typological differences arise from cultural, social and economic differences, and individualities from topographical and historical specificities. In effect, it is proposed that there exists a fundamental settlement process, which is more or less invariant across cultures, and that spatial cultures are parameterisations of this process by, for example, creating different degrees and patterns of integration and intelligibility, and different degrees of local and global organisation to the overall form. Our task here is to show what this fundamental settlement process is and how it is a product of generic function and the laws of spatial emergence.

Before we embark on this, we must first be clear what exactly it is we are seeking to explain. It is clear that when settlements are small, they can take a great variety of forms. It is also clear that throughout history we find quite radical experiments in urban form, for example, the cities which we examined in Chapter 6. However, as cities become large, these peculiarities tend to be eliminated, and grids become much more like each other in certain ways. What we are seeking to identify here are the invariants in the processes by which large cities tend to grow — that is, to try to describe the main lines of urban evolution. ‘Strange’ cities exist, and for a while even grow quite large, but they are essentially dead ends in urban evolution. Their principles of organisation do not support a large successor family of cases and types across the range of urban scales.

Because they operate at a very deep level and govern the common structure of cities, it might be thought that the fundamental city is too generalised to be of real interest. This is not the case. The influence of spatial laws on cities is pervasive as well as deep. It effects the level at which we see and experience cities, as well as at the level of their deep structures. In order to understand individual cities and types of cities at any level we must first understand exactly what it is that these general laws have contributed to their form. If we think of cities as aggregates of cellular elements — buildings — linked by space, then in the language of the previous chapter, spatial laws are the ‘first filter’ between the boundless morphological possibility for such aggregates and the properties of the vanishingly small subset we call cities. Social and economic processes are then the second filter, guiding the basic paths of evolution this way or that to give rise to recognisable types. Specific local conditions in time and space are then the third filter through which the city acquires its eventual individuality.

Our task in understanding the fundamental city is then to answer two questions: how and why should these particular invariants emerge from a spatial process of generation? And what aspects of the social and functional processes that drive settlement formation guide growing cities along these pathways? The answer to both questions will be essentially those we have discussed in the previous chapter: laws of spatial implication from local physical moves to overall spatial pattern in cellular aggregates — for such cities are — these being driven by ‘generic function’, in conjunction, of course, with prevailing socio-economic and topographical factors.


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