Is Design Theory Possible

ABSTRACT Because design is a practice, a theory of design is not possible in the same sense as a theory of chemistry is. Socio-psychological theories of what designers do are not design theories. Knowledge of how to design cannot be reduced to theory, for reasons that grow out of the philosophy of science. This paper suggests, however, that there can be a theory of design in the sense of supporting theory, drawn from other disciplines, that employs a level or style of analysis that is uniquely suited to design practice. In particular, design theory might involve incompletely described objects or teleological explanation, since these are key features of design, and since the design process can be understood as moving from a functional description to a physical description of an object. INTRODUCTION The notion of a theory of design is problematic because design, like medicine or management, is a practice. Whereas chemistry or physics is defined by a set of phenomena it is assigned to study, design is defined by a task it is assigned to do. Chemical theory is clearly possible because one can organize one's knowledge of chemical phenomena in a systematic way. But it is not obvious that one can reduce knowledge of design practice to theory. I will argue that it is impossible to do this, for reasons that derive from a body of thought in the philosophy of science. I do not dispute that one can theorize about design practice in the sense that one can theoretically understand the socio-psychological phenomenon of design. But this, I will argue, does not issue in design theory. My claim is that one cannot theoretically organize one's knowledge of how to design. Despite this negative conclusion, I will identify a sense in which design theory is possible. Practical arts like design, medicine, and engineering are typically assisted by supporting theories that provide techniques and a basic understanding of the phenomenon one is trying to influence. These theories are generally part of other sciences. But a supporting theory may investigate a phenomenon, or employ a level or style of analysis, that is unique to the practice in question. At an extreme, one could say that even chemical theory is a supporting theory uniquely suited to the practice of chemistry, albeit one that does not reduce to theory all the knowledge required to practice chemistry. The possibility of design theory, then, turns on whether there are theoretical styles or subject matters that support design practice and are uniquely associated with it. I will suggest that there are. But on this understanding, design theory is in its infancy, and my rumination about what it might become must be treated as speculation. I begin below with a brief discussion of what is meant by "theory." After an even briefer definition of "design," I argue that a socio-psychological understanding of the design process is important but is not design theory. I then argue at some length that one cannot reduce practical design knowledge to theory. But this leaves open the possibility that there are supporting theories unique to design, and I suggest ways in which these can arise from the need to understand the behavior of incompletely described objects, which are characteristic of design. In particular, I discuss the potential for design theory in computational models, design representations, optimization models, and empirical investigations. I also point out that since part of what it means to design is to concoct a functional or teleological explanation of the resulting artifact, teleological theories can play a special role in design. I defend the notion of teleological explanation and suggest how it might lead to design theories. I make no attempt to survey systematically the literature that might be relevant to design theory. Several useful surveys can be found in the literature (Cross, Naughton and Walker 1980; Hubka 1980; Simon 1969; Suhl 990). …