1 The City as One Thing

This paper summarises the latest theories in the field of space syntax. It opens with a discussion of the relationship between the form of urban grids and the process of how cities are formed by human activity; this is done by a comprehensive review of space syntax theory from its starting point in the 1970s. The paper goes on to present research into how cities balance the micro-economic factors which shape the spatial structure of cities with the cultural factors that shape the underlying form of residential areas. It goes on to discuss the relationship between activity and space and how this relationship is formed by the way different activities make different demands on movement and co-presence. The paper ends with a discussion regarding the manner in which patterns of spatial integration influence the location of different classes and social groups in the city and contribute to the pathology of housing estates. The paper concludes that spatial form needs to be understood as a contributing factor in forming the patterns of integration and segregation in cities. Is The City One Thing Or Two? On the face of it, the city is two things: a large collection of buildings linked by space, and a complex system of human activity linked by interaction. We can call them the physical city and the social city. Urban practice and theory must connect one to the other. But the reflective disciplines which support and nourish both roughly the morphological disciplines on one side and the social sciences on the other in their nature take an asymmetric view, foregrounding one city and backgrounding the other, in effect seeing the ‘other’ city through the foregrounded one, and so at best as a shadowy set of patterns and forces. It is no surprise then that, at the start of the twenty first century, we have many partial theories about the city, but no theory of the city as both of the things that it seems to be. But is the city in any case two things or one? It will be one to the degree that the physical and social cities act conjointly to produce significant outcomes. There are good reasons why in principle we might expect it to be one thing. The social city is either side of the physical city: it brings it into existence, and then acts within the constraints it imposes. It seems unlikely that either is a wholly contingent process. But both relations raise uncomfortable issues of determinism: how can a physical process in the material world relate to a social process in a non-trivial yet systematic way. This places philosophical as well as methodological obstacles in the path of reflection and research. In practice, we also find that any time, intervention in the city is governed by a consensus of beliefs and practices about the city as one thing: that small scale inward looking residential developments promote community, for example, or that mixed use reduces crime, or that lower densities lessens the danger of social malaise. But these beliefs shift over time, often dramatically, and it is hard to think of a case where a one thing proposition has acquired the status of a tested – or even testable – scientific proposition. The beliefs and practices allow us to act as though the city were known to be one thing, because this provides a rationale for our interventions, but all our formations and paradigms make the tacit assumption that the cities can safely be treated as two. Paradoxically, the real challenge to our two city paradigms comes not from the well-formed, wellfunctioning city, but from its real or apparent pathology. Where cities seem to go wrong, often as a result of belief-based interventions which come in time to appear mistaken, the problem of one city confronts us with immediacy and urgency by demanding to know if there is any sense in which the physical and spatial form of our interventions has contributed to their apparent failure. The challenge was posed in the second half of the twentieth century by the precipitate decline of many ambitious social housing schemes, and the widespread public belief that the physical and spatial form of these experiments was somehow involved. Today it is posed in a more general form as the problem of the social segregation in the city, its nature, its causes and its consequences. We can easily formulate ideas about segregation purely in terms of social and economic factors without invoking space. But segregation is a spatial term and the way in which patterns of segregation and exclusion cluster in the city leads us back to the one city question: does urban segregation have a significant physical meaning over and above its social meaning? Can segregation be, or become, a one city phenomenon? The idea of space syntax Space syntax was conceived in the nineteen seventies as an attempt to address this kind of one city question. Its genesis was in the remarkable architectural changes which began to appear in cities like London in the nineteen sixties, and the increasing sense which they engendered of a contradiction between – as seemed at the time their striking architecture and the discomfiting and un-urban nature of their spaces. Space syntax began from the observation that space is the common ground of the physical and social cities. The physical city is a complex pattern of space, while all social activity and interaction happens in space. In itself, of course, this leads to an impasse. All social activity leaves spatial traces in the form of recursive patterns, but how can these relate to a physical and spatial context whose essential patterns were in all likelihood laid down long ago, under the influence of quite different social circumstances? On reflection, the radically different rate of change of the physical and social cities seems in itself to forbid anything but a contingent relation between the two. But space syntax added to the existing panoply of spatial concepts a new one that potentially reshapes research questions: spatial configuration. The hope was that by learning to describe and analyse different kinds of spatial configuration, or pattern, in the city – for example the differences between the new social housing and traditional urban areas, which seemed prima facie to be critically different – it would be possible to detect any influence there might be of social factors in the construction of the these spatial patterns and also to explore any consequences there might be in terms of how social life could and did take place. By learning to control the spatial variable at the level of the complex patterns of space that make up the city, we might begin to gain insight into both the social antecedents and consequences of spatial form, and so detect signs of the social city either side of the physical city. In syntax terms, spatial configuration means relations between spaces which take into account other relations, and so in effect relations between all the various spaces of a system. Space syntax, in effect, takes certain common measures of relationality in graphs, and first theorises them in terms of their potential to embody or transmit social ideas, and then turns them into measures and representations of spatial structure by linking them to geometric representations of the system of spaces under examination (Hillier and Hanson 1984). These measures are essentially formal interpretations of the notion of spatial integration and segregation, and it was the formalisation of these terms which first seemed to identify structures which linked the social and the spatial. Providing a measurable scale from segregation to integration, enabled statistical comparison of different spatial forms across cultures, and so provide a platform from which social origins and consequences might be investigated. This was an unfamiliar idea. It was, in effect, being suggested that space has its own formal logic prior to acquiring a social logic, and indeed that it was this logic of space that was exploited in order to render space social. This is the core argument of ‘The Social Logic of Space’. The autonomous potential of space to form patterns was, in effect, seen as the means through which it is able to give expression to social meanings. This challenged paradigms on both side of the two city divide. But it also suggested that there could be a one city approach to urban research which was both quantitative and informed by the search for social and cultural influences and meanings. From these beginnings, space syntax has evolved into a set of tools linked to a set of theories, the two together giving rise to a set of interpretative models for different socio-spatial phenomena. Interpretative models are schemes of analysis which work for particular phenomena. For example, we have an urban movement model, a land use model, a crime model, even a social segregation model, and most important of all a general urban model in which the integration-segregation dimension is shown to be a primary spatial dimension on which cities are organised. These models are quite unlike the more familiar engineering models, since they seek to be explanatory in themselves of the phenomena they address. They show that by clarifying space in a particular way the social origins and consequences of the spatial patterns can be brought into clear view. It is because they seek to be explanatory in themselves that syntax models have proved to be so applicable in design. In what follows we first explain the foundations of space syntax, and go on to give an overview of the range of techniques that are now available, and what questions can be addressed with them. We then outline the general theory of the city to which this has given rise, which shows why the issue of integration-segregation is close to the heart of what cities are when considered as one thing. We then outline a series of characteristic research problems that have been addressed with space syntax, and the kinds of models we have developed to try to solve them. We follow this with sketches of a few of the hundreds of projects on which space syntax has been applied in recent years, and introduce the other parts of this special issue.