Urban form as a stochastic equilibrium: some applications of Alan Turing's morphogenetic model

Cities as organisms in constant transformation can be described with the aid of models based on dynamic and complex systems. Among the different possibilities, we will analyse Alan Turing's morphogenetic model as an exemplary case: it has been initially used to account for the growth of living beings, but it has been later applied to many different fields as well. Its adequacy to describe the development of cities lies in the fact that it is a stochastic model, where the interaction between a series of local forces gives rise to global arrangements that cannot be actually predicted. We will deal with some of the most relevant approaches in urban morphogenesis related to these theories in order to prove that, from this point of view, there are analogies between phenomena that occur in the natural and in the artificial domain and that cannot be explained making use of a hylomorphic scheme, according to which form is imposed to an inert matter. On the contrary, form emerges through a mechanism of self-organisation whose description requires particular eidetic categories.