This book is the third in a series of publications on Open Design. The first, Open Design: A Collaborative Approach to Architecture by Lex van Gunsteren and Peter-Paul van Loon, opens with the question ‘Why, so often, do we build what no one wants?’ Considering that despite the accumulation of much knowledge and the identification of important basic principles there is no theory of design, it is perhaps not surprising that the outcome of design is not always satisfactory.

Design is a complex, multi-faceted process with many factors contributing to successes and failures. As in other fields, the Open Design group at Delft has identified the process of collaborative decision making in design as one of these key factors. A single designer contemplating a simple design problem usually faces the difficult task of reconciling multiple conflicting goals while large urban planning projects are not simple and usually involve multiple players with conflicting goals in addition to other challenges.

Until recently, the scientific discipline that deals with these issues – decision theory, which in turn is based on the theory of measurement – had little to offer. In the case of group decision making, i.e. the case of multiple stakeholders or players, based on misinterpretations of the meaning of ‘Arrow's Impossibility Theorem,’ this problem has been commonly viewed as unsolvable. In contrast, in the case of a single decision maker with conflicting multiple criteria, the literature offers a bewildering number of methodologies that produce contradictory results. Since their results are contradictory, at least some of these methodologies cannot be correct but the literature offers little guidance on how to evaluate such methodologies besides numerical comparisons from which nothing can be learned except that they are different. Even in the case of a single decision maker and a single measurement attribute (or a single evaluation criterion), none of the models of the classical theory of measurement produce scales that enable the operations of addition and multiplication and even elementary variables such as position of points on a straight line is not modelled correctly.

Rather than following the classical theory of decision making, Open Design utilizes a sophisticated linear programming model to capture the elements of group decision making. The limitations of this linear model seem more acceptable than those of the tools of classical decision theory in view of the fact that recent analysis reveals foundational problems with the application of mathematical operations to the social sciences and, in particular, with the theory of measurement, decision theory, utility theory, game theory, economics and other disciplines. A new theory that addresses these issues has been developed and the challenges of integrating its practical application into design are being studied by the Open Design group.

Open Design is a significant contribution to architectural design but its impact will be felt beyond its applications in this field. The challenge which this book addresses is the integration of existing and new methodologies and tools from diverse fields such as management, negotiation, decision theory and preference modelling, linear and non-linear programming, simulation, risk assessment, regression analysis, and geometric modelling into a single coherent design methodology that synthesizes technical and social aspects of group design and group decision making.

Naturally, the development of Open Design is an ongoing undertaking. Although much progress has been made and Open Design is already a methodology of great value, undoubtedly it will continue to evolve. This book provides a view of its current state and hints of its future direction.

Jonathan Barzilai, Dalhousie University