1. The Design Question
[New ideas would come about] by a connexion and transferring of the observations of one Arte, to the uses of another, when the experience of several misteries shall fall under consideration of one mans minde.
SIR FRANCIS BACON [1605], THE TWO
BOOKS OF THE PROFICIENCE AND
ADVANCEMENT OF LEARNING, BOOK 2, 10
Few engineers and composers ... can carry on a mutually rewarding conversation about the content of the other’s professional work. What I am suggesting is that they can carry on such a conversation about design, . . . [and then] begin to share their experiences of the creative professional design process.
HERBERT SIMON [1969], THE SCIENCES
OF THE ARTIFICIAL, 82
Is Bacon Right?
Sir Francis Bacon’s hypothesis is our challenge. Are there invariant properties of the design process itself, properties that hold across a wide range of media of design? If so, it seems likely that designers in one medium would collectively grasp some of these principles more clearly than other designers, through struggles that are peculiarly difficult for that medium. Moreover, some media, such as buildings, have longer histories of both design and meta-design—“the design of design.” If all this is true—and if Bacon’s conclusion is true—designers in different media can expect to learn new things about their own several crafts by comparing their experiences and insights.
What Is Design?
The Oxford English Dictionary defines the verb design as
To form a plan or scheme of, to arrange or conceive in the mind . . . for later execution.
The essentials of this definition are plan, in the mind, and later execution. Thus, a design (noun) is a created object, preliminary to and related to the thing being designed, but distinct from it. Dorothy Sayers, the English writer and dramatist, in her magnificent and thought-provoking book The Mind of the Maker, breaks the creative process out further into three distinct aspects. She calls them the Idea, the Energy (or Implementation), and the Interaction,1 that is,
1. The formulation of the conceptual constructs
2. Implementation in real media
3. Interactivity with users in real uses
A book, in this conception, or a computer, or a program, comes into existence first as an ideal construct, built outside time and space, but complete in essence in the mind of the author. It is implemented in time and space, by pen, ink, and paper; or by silicon and metal. The creation is complete when someone reads the book, uses the computer, or runs the program, thereby interacting with the mind of the maker.
In an earlier paper, I divided the tasks in building software into essence and accident.2 (This Aristotelian language is not to denigrate the accidental parts of software construction. In modern language the terms would more understandably be essential and incidental.) The part of software building I called essence is the mental crafting of the conceptual construct; the part I called accident is its implementation process. Interaction, Sayers’s third step, occurs when the software is used.
The design is thus the mental formulation, which Sayers calls “the Idea,” and it can be complete before any realization is begun. Mozart’s response to his father’s inquiry about an opera due to the duke in three weeks both stuns us and clarifies the concept:
Everything has been composed, just not yet written down.
LETTER TO LEOPOLD MOZART [1780]
For most human makers of things, the incompletenesses and inconsistencies of our ideas become clear only during implementation. Thus it is that writing, experimentation, “working out,” are essential disciplines for the theoretician.
The phases of Idea, Implementation, and Interaction operate recursively. Implementation creates a space in which another cycle of design must be done. Thus Mozart Implemented his opera Idea with pen on paper. The conductor, Interacting with Mozart’s creation, conceived an Idea of an interpretation, Implemented it with orchestra and singers, and the Interaction with the audience completed the process.
A design is a created object; associated with it is a design process, which I shall call design, without any article. Then there is the verb to design. The three senses are intimately related; I believe context will resolve ambiguity.
What’s Real? The Design Concept
If a number of individuals have a common name, we assume them to have also a corresponding idea or form:—do you understand me?
I do.
Let us take any common instance; there are beds and tables in the world—plenty of them, are there not?
Yes.
But there are only two ideas or forms of them—one the idea of a bed, the other of a table.
True.
And the maker of either of them makes a bed or he makes a table for our use, in accordance with the idea.
PLATO, THE REPUBLIC [360 BC], BOOK X
At the 2008 Design Thinking Research Symposium 7, each of the speakers presented analyses of the same four design team meetings.3 Videos and transcripts had been distributed well in advance.
Rachael Luck of the University of Reading identified in the architectural conversations an entity that none of us had remarked but all then recognized: the Design Concept.4
Sure enough, both architect and client referred from time to time to this shared invisible entity. Speakers usually gestured vaguely toward the drawings when they spoke thus, but it was clear they were not referring to the drawings or any particular thing therein. Always, the concern was for the conceptual integrity of the developing design.
Luck’s insight made the Design Concept a thing in its own right. This resonated strongly with my experience. When the IBM System/360 “mainframe” computer family’s single architecture was being developed (1961–1963), such an entity was always present in the architecture group, although never named. Exploiting Gerry Blaauw’s brilliant insight, we had explicitly separated the System/360 design activities into architecture, implementation, and realization.5 The basic concept was a computer family with one face to the programmer—the architecture—and multiple concurrent implementations at various positions on the performance and price curves (Chapter 24).
The very simultaneity of multiple implementations, with their several engineering-manager champions, drove the common architecture toward generality and cleanliness and insulated it from small cost-saving compromises. These forces, however, were merely shields for the instincts and desires of the architects, who each wanted to make a clean machine.6
As the architecture design progressed, I observed what at first seemed quite strange. For the architecture team, the real System/360 was the Design Concept itself, a Platonic ideal computer. Those physical and electrical Model 50, Model 60, Model 70, and Model 90 things under construction out on the engineering floors were but Plato’s shadows of the real System/360. The real System/360’s most complete and faithful embodiment was not in silicon, copper, and steel, but in the prose and diagrams of IBM System/360 Principles of Operation, the programmer’s machine-language manual.7
I had a similar experience with the View/360 beach house (Chapter 21). Its Design Concept came to be real long before any construction began. It persisted through many versions of drawings and cardboard models.
Interestingly enough, I never felt such a Design Concept entity of the Operating System/360 software family. Perhaps its architects did; perhaps I did not have an intimate enough acquaintance with its conceptual bones. Perhaps the Design Concept didn’t emerge for me because OS/360 was in fact a fusion of four somewhat separate parts: a supervisor, a scheduler, an I/O control system, and a large package of compilers and utilities (Chapter 25).
What’s the Value?
Is there positive value to recognizing an invisible Design Concept as a real entity in design conversations? I think so.
First, great designs have conceptual integrity—unity, economy, clarity. They not only work, they delight, as Vitruvius first articulated.8 We use terms such as elegant, clean, beautiful to talk about bridges, sonatas, circuits, bicycles, computers, and iPhones. Recognizing the Design Concept as an entity helps us to seek its integrity in our own solo designs, to work together for it in team designs, and to teach it to our youth.
Second, talking frequently about the Design Concept as such vastly aids communication within a design team. Unity of concept is the goal; it is achieved only by much conversation.
The conversation is much more direct if the Design Concept per se, rather than derivative representations or partial details, is the focus.
Thus, moviemakers use storyboards to keep their design conversations focused on the Design Concept, rather than on implementation details.
Detailing will of course surface conflicting versions of the Concept and force resolution. For instance, System/360 architecture needed a decimal datatype, as a bridging aid for thousands of existing users of IBM’s decimal machines. Our developing architecture already had several datatypes, including a 32-bit fixed-point twos-complement integer and a variable-length character string.
The decimal datatype could be made similar to either one. Which choice better fit the Design Concept of System/360? Strong arguments were made each way; the strength of each depends on one’s version of the Design Concept. Some of the architects had implicit Design Concepts reflecting earlier scientific computers; others’ implicit concepts reflected earlier business computers. System/360 was explicitly intended to serve both kinds of applications well.
We chose to model the decimal datatype after the character-string one, the one more familiar to the largest particular user community of the decimal datatype, IBM 1401 users. I would decide that way again.
Thinking about the Design Process
Thinking about designs has a long history, going back at least to Vitruvius (died ca. 15 BC). His De Architectura is the important book about design from the Classical period. Major milestones are the Notebooks of Leonardo da Vinci (1452–1529) and the Four Books of Architecture by Andrea Palladio (1508–1580).
Thinking about the design process itself is much more recent. Pahl and Beitz trace German thought from Redtenbacher in 1852, stimulated by the rise of mechanization.9 For me, major milestones have been Christopher Alexander’s Notes on the Synthesis of Form (1962), Herbert Simon’s The Sciences of the Artificial (1969), Pahl and Beitz’s Konstructionslehre (1977), and the founding of the Design Research Society and the starting of the journal Design Studies (1979).
Margolin and Buchanan [1995] is an edited collection of some 23 essays from the journal Design Issues, primarily design criticism and theory, with “occasional ventures into philosophical issues that bear on the understanding of design” (p. xi).
My The Mythical Man-Month [1975, 1995] reflects on the design process for IBM’s Operating System/360, later evolved to MVS and beyond. It emphasizes the human, the team, the management aspects of that design and development project. Of particular relevance to the present work are Chapters 4–6 of those essays, which address how to achieve conceptual integrity in a team design.
Blaauw and Brooks [1997], Computer Architecture: Concepts and Evolution, includes extensive discussion of the design of the IBM System/360 (and System/370–390–z) architecture and the relationships of and rationales for dozens of design decisions. It doesn’t treat the design process or human aspects of designing at all. But Section 1.4, which discusses criteria for goodness in computer architectural design, is indeed of particular relevance for this work.
Kinds of Design
System Design versus Artistic Design
This book is about the design of complex systems, and the viewpoint is that of the engineer, an engineer focused on utility and effectiveness but also on efficiency and elegance.
This contrasts with much of the design done by artists and writers, whose emphasis is on delight and the conveying of meaning. Architects and industrial designers, of course, fall into both camps.
Routine, Adaptive, Original Design
We often think of bridge design as one of the high arts of engineering, one where breakthroughs in concept or of technology have dramatic and highly visible cost, function, and esthetic consequences.
Well, a high fraction of all highway bridges are short, so cranking out a design for a 50-foot concrete bridge is a routine and automatable process. For short bridges, civil engineers know, and long ago codified into handbooks, the design decision tree, the constraints, and the desiderata. The same situation prevails for the design of compilers for established languages on new platforms. There are many areas of routine, automatable design.
The emphasis in this book is on original design, as opposed to the routine redesign of object after object with changed parameters, or even adaptive design, which is essentially the modification of a preceding design or object to serve new purposes.
Notes and References
1. Sayers [1941], The Mind of the Maker.
2. Brooks [1986], “No silver bullet.”
3. McDonnell [2008], About Designing. This book is the edited Papers from the Design Thinking Research Symposium (DTRS7).
4. Luck [2009], “Does this compromise your design?” reprinted in McDonnell [2008], About Designing.
5. Blaauw and Brooks [1964], “Outline of the logical structure of System/360.” Blaauw further divides Sayers’s “Energy” into Implementation and Realization, a distinction I find immensely useful.
6. Janlert [1997], “The character of things,” argues that designed things have character and discusses how one designs that character.
7. IBM Corp. [1964], IBM System/360 Principles of Operation.
8. Vitruvius [22 BC], De Architectura.
9. Pahl and Beitz [1984], Engineering Design.