Generative methods in urban design: a progress assessment

The year 2007 marked the 20‐year anniversary of A New Theory of Urban Design (1987), a slender volume by Christopher Alexander and colleagues that serves as a notable milepost within the half‐century old “design methods movement” in which Alexander himself played a seminal role. The “generative” design method of A New Theory focused less upon the specification of a final form through schematic planning, and more on the stepwise process by which a form might emerge from the evolutionary actions of a group of collaborators. In so doing, it challenged the notion of “design” as a progressive expression of schematic intentions, and argued for a conception of design as a stepwise, non‐linear evolution in response to a series of contextual urban factors. In the 20 years since, significant progress has been made to develop the insights of generativity in urban design, as in other fields. Some of Alexander’s ideas have been incorporated – notably by practitioners of The New Urbanism – and some have been challenged and dismissed, including, notably, by Alexander himself. The author assesses progress since this milepost volume – substantial, he argues – as well as setbacks and shortcomings, and significant opportunities still remaining.