The following quoted passage is by R. Buchanan, PhD., from his essay Design and the New Rhetoric: Productive Arts in the Philosophy of Culture, published in Philosophy and Rhetoric, Vol. 34, No. 3, 2001. Copyright 2001, Penn State University.
My intention in typing this up is to help those struggling to define UCD, IxD, and related concepts, by providing insights from a rhetorical POV. I hope you find this useful!
The rhetorical uses of definition offer a good beginning point for clarifying the nature of design. For rhetoricians, definitions serve strategic and tactical purposes in inquiry. They do not settle matters once and for all, as many people seem to believe they should. Instead, they allow an investigator or a group of investigators to clarify the direction of their work and move ahead with inquiry in a particular thematic direction. Rhetoricians recognize many kinds of definition, ranging from commonplace definitions of ordinary usage to descriptive and formal definitions. Commonplace definitions are adequate for settling the issue of name, but descriptive and formal definitions serve to identify a direction for thematic investigation of the nature of a subject. Descriptive definitions, for example, tend to identify a single primary cause of a subject and point toward how that cause may be explored in greater depth and detail, allowing an individual to create connection among matters that are otherwise not easily connected. When designer Paul Rand says, for example, “Design is the creative principle of all art,” he identifies individual creativity as the most important cause of design. In similar fashion, when cognitive psychologist Herbert Simon says, “Everyone designs who devises courses of action aimed at changing existing situations into preferred ones,” he identifies cognitive processes of decision-making as the key to understanding design. THere are many descriptive definitions of design, and they are as varied as the insights of human beings and as varied as the causes that may account for design.
Formal definitions are somewhat different. They tend to identify several causes and bring them together in a single whole, suggesting relationships that may be explored through further inquiry. Functional integration is the primary principle of such a definition, rather than the separate causes considered in isolation. There are fewer formal definitions of design than descriptive definitions, but formal definitions play an important role. They serve to establish the boundaries of a field and relate many otherwise separate lines of inquiry in a common enterprise. One formal definition that may serve this purpose is the following: “Design is the human power of conceiving, planning, and making products that serve human beings in the accomplishment of any individual or collective purpose.” Whether this is an immediately compelling definition–formal definitions are seldom as dramatic or vivid as a good descriptive definition–it does bring together the variety of themes and causes that are explored in the study and practice of design. If we wish to consider Aristotle’s four causes for a comparison with his definition of rhetoric, the formal definition of design identifies: (1) The creative capacity of individual designers as an efficient cause; (2) the sequence of goals around which the methods of design thinking and practice have taken shape as a final cause; (3) the outcome of the design process in products that serve human beings as a formal cause; and (4) the subject matter of design as found in any of the activities and purposes of human beings as a material cause. The lack of further specification in the material cause is significant, because design, like rhetoric, may be applied with regard to any subject. Design has no fixed subject matter, which explains why it continues to evolve in a surprising array of new applications and extensions. In essence, the definition suggests that design is an art of invention and disposition, whose scope is universal, in the sense that it may be applied to the creation of any human-made product. This makes of design as an art of forethought, as traditional rhetoricians perhaps regard their discipline as an art of forethought in verbal communications.
At this point we may being to ask whether design is a modern form of rhetoric–or whether rhetoric is an ancient form of design. Although we tend to think of the products of design as artifacts–graphics and industrial objects–there is nothing in our formal definition that would forbid us to consider traditional verbal rhetoric as a species of design. This inversion may seem strange and unfamiliar, yet it accords with our understanding of how information is shaped in persuasive argumentation and how, in contemporary life, it often emerges in new products of technology. If rhetoric provides systematic forethought in all of the distinct forms of making in words, why should it not be considered an art of design?
Note: Aristotle’s definition of rhetoric similarly identifies efficient, final, and formal causes, but treats the material cause in the phrase “with regard to any subject.” In Aristotle’s analysis, style is simply the material cause of a speech rather than the subject matter or material cause of the art of rhetoric itself.