Reviewed by
Anne van der Veen
Institute for Geo-Information Science and Earth Observation, University of Twente
10 years ago Alasdair Turner (2002) reviewed Self-Organization and the City by Juval Portugali. Now, the same author published a new book where cognition pops up in the title. The review by Turner was very positive and I am also inclined to express my admiration: What a book! It took me some time to digest it, but I strongly recommend it to scholars who work on spatial agent models. On the other hand, I would like to warn the readers as the book suggests a synergetic approach to agent-based modelling, which many of us are unfamiliar with. Moreover, although being almost perfect, the book missed something that crept into my brain while reading these 400 pages.The book starts from a presentation of the history of urban research, which revolves around the description of two cultures: first, the quantitative revolution in the theories of the City and, secondly, a structuralist-Marxist, humanistic approach. An approach called "Complexity Theories of the City (CTC)" is presented as a third line, which is based on self-organization and complexity and follows the paradigm of Haken's synergetics (note that even Haken contributed to some book chapters). The idea of synergetics points to pattern configurations and their order parameters. The idea is that order parameters compete each other in enslaving the system, which means that the system eventually depends on the movement of the winning parameter. In this view, cellular automata and agent-based systems are nothing but simple qualitative models as they refrain from complicated non-linear mathematics.
Portugali criticises CTC models in that they are not capable of handling crucial qualitative issues, which are important to understand the growth and development of urban cities. Moreover, in simulation models the medium has become the message: too often complexity theories of cities and cities themselves are seen through the eyes of cellular automata/agent-based models, i.e., as the product of interaction among cognitively simple agents that give rise to cities and complex systems of cities from the bottom-up.
In this respect, the introduction of cognition makes the real difference compared to the previous book mentioned above. In this new book, Portugali introduces new theories, materials and evidence that improve the current simplistic simulation models of the city. Indeed, the overall dynamics of any cellular automata/agent-based model is basically a bottom-up process of agents seeking cells to fill who interact and create emergent properties, without any relevant cognitive processes seriously involved. The new model proposed in this book includes a constant top-down/bottom-up synergetic process in which agents cognize cities, select areas and cells, locate themselves in the space, transform cells, areas, and cities so that new agents cognize cities and so on. In my opinion, this 'cognitive turn' is a significant improvement in urban theories and may also motivate new developments in social simulation.
This said, being an economist, I have missed certain features of standard regional economic theory, which has significantly contributed to the recognition of the importance of space in economics. I refer here to the advantages of agglomeration in urban and localised economies. At the end of the book, Portugali dealt with an assignment problem related to how to allocate agents into space. This is a typical competition problem and in this case Portugali included a cost/attractiveness function in his synergetic mathematical equations. On the other hand, given that Portugali focused on cognitive aspects of agent behaviour, such as handling internal information of intentions and external information of the city, he did not recognise the importance of certain economic processes that could even change the quality of the land use and so have important implications for understanding cities.
To sum up, this is a book well worth reading. Furthermore, it allows us to highlight certain limitations of social simulation in dealing with complex cognitive processes and complex system modelling. For instance, how many of us would be capable of programming synergetics theory, being locked in into Netlogo and Repast platforms?
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