InterJournal Complex Systems, 1005
Status: Accepted
Manuscript Number: [1005]
Submission Date: 2004
Understanding the Complexity of Design
Author(s): Jonathan R. A. Maier ,Georges M. Fadel

Subject(s): CX.6



The powerful concept of complexity can be applied to help us understand not only modern engineering systems, but also the design of those systems, and artifacts in general. In this paper we attempt to establish a two-pronged theoretical framework for understanding the complexity of design. By design we mean the activity of designing artifacts in general, not any specific class of artifact. The first route to understanding the complexity of design is based on a fundamental exploration of what it means for a system to be complex. This avenue is essentially mathematical in character, and for it we rely heavily on the works of Robert Rosen, Nicholas Rashevsky, and Peter Wegner. Having discussed briefly the foundations of this approach, it is then applied to the science of design. In particular, the goal is to show that design in general is a member of the class of systems that are formally described as open and complex, and not a member of the class of systems that are formally described as closed and algorithmic. This amounts to theoretical validation for adopting a paradigm for using an open relational concept, such as affordance, as a basis for design, rather than a closed algorithmic concept such as function. This approach also suggests abstract affordance based descriptive models of design as alternatives to the current function based models of design. The second route to understanding the complexity of design lies in the study of systems that are in some obvious way complex. This approach is essentially empirical in character. Accordingly, the goal here is to show that design exhibits similar characteristics to other complex systems, in particular, as will be shown, a class of complex systems known as Complex Adaptive Systems (CAS). This constitutes more validation for using a relational as opposed to an algorithmic concept as a basis for design. Also, this suggests that design may be modeled in the same way as other CAS, i.e., in accordance with a cycle in which other CAS are known to operate In place of algorithms, what is needed for complex systems are structures which are semantically rich and open to interactions. For biology, such a formalism, once he realized such a thing was necessary, was invented by Rashevsky in the form of relational models [Rashevsky 1960], to replace the earlier simplistic machine metaphor dating back to Descartes. For computer science, such a formalism was invented by Wegner in the form of interaction machines [Wegner 1997, 1998], to replace the much more restrictive and simplistic Turing machines (e.g., [Turing 1959]). For design, we propose that the appropriate formalism is that of affordance [Gibson 1979; Maier and Fadel 2001a, 2002, 2003], rather than the much more restrictive and simpler concept of function, which is very similar to that of algorithm, as explained in this chapter. The concept of affordance, thus grounded theoretically in the first approach to design complexity (the relational approach), agrees very well with the empirical model for design complexity suggested by the CAS-type approach. The integration of the concept of affordance into the CAS-inspired model for design thus concludes this paper.

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