CHAPTER 1. OVERVIEW

The following chapters present a theory of computer support for innovative (non-routine), cooperative design based on an analysis of interpretation in design. They will argue that the central impediment to computer support of innovative design is that designers make extensive use of situated tacit understanding while computers can only store and display explicit representations of information.

The process by which designers transform their tacit preunderstanding into explicit knowledge is termed interpretation. (See Part I for an analysis of interpretation in design.) Interpretation is central to the process of solving design problems and is part of the process of collaborating with other designers; the explicit knowledge that is generated by this interpretation is therefore a natural by-product of innovative, cooperative design. (See Part II for a theory of computer support based on this generated knowledge.) Representations of this knowledge defined using computer-based design support systems can be captured by these systems for the support of subsequent design work, including the maintenance and modification of the designed artifacts. (See Part III for details of a computer system for supporting interpretation in design.)

Chapter 1 provides a chapter-by-chapter overview of the dissertation. It discusses the claims, arguments, and themes that arise in each of the subsequent chapters, without going into the detail necessary to defend the claims, support the arguments, or work out the themes. Its purpose is to provide a readers’ guide to the flow of the dissertation, motivating how one discussion leads into or provides the background for another. Section 1.1 offers a preliminary presentation of the central concept of interpretation, anticipating the analysis of this concept from various approaches in the dissertation. Each of the other sections provides an overview of a specific chapter.

1.1.      Understanding Interpretation

To say that interpretation is central to innovative design is to stress that in order to design the designer must to some degree understand and be able to articulate the significance of the artifact being designed. This may include, for instance, understanding what is desired in a task specification, how possible composite parts of the artifact will function and interact, or how people can use the designed artifact. According to the analysis presented below, such understanding is possible for people but not for computers. People understand things because they are actively involved with them in the world. The significance of artifacts for a person is determined by the artifacts’ relationships to other artifacts, activities, and people whose significance is already understood as part of the person’s situation. Understanding combines personal and socially shared perspectives on the world. All of this takes place primarily in tacit ways, i.e., unverbalized. However, one’s tacit understanding of something can be partially articulated or expressed explicitly in spoken, written, or graphical language—either to deepen one’s own understanding or to communicate with others.

Two aspects of the process of interpretation can be distinguished.

(1) There is a tacit preunderstanding based on previous background knowledge; items from this preunderstanding can be articulated explicitly.

(2) There is the possibility of revising that preunderstanding based on discoveries that are opened up by it.

That is, one can interpret something as something that one already knows about, or as a variation that differs from that in ways that are discovered as a result of the breaking of one’s tacit expectations. Accordingly, interpretation in innovative design involves both human understanding of extensive background and a creative ability to revise one’s understandings iteratively.

The analysis of interpretation developed below distinguishes three characteristics of interpretation: being situated, having a perspective, and using language.[1]

(a) Being situated means that what is to be interpreted is tacitly understood by virtue of its associations within an open-ended network of related artifacts, people, human purposes, and other concerns. All of these associations are themselves understood as part of one’s background understanding of one’s involvements.

(b) Having a perspective means that there is a focus on a certain aspect or that a specific approach is taken in interpreting something.

(c) Using language means that a particular vocabulary is available as part of a tradition that provides a conceptual framework for the interpretive task.

Each of these characteristics of interpretation is grounded in a form of preunderstanding that can be transformed through a corresponding phase of discovery. This two-dimensional structure is presented in Table 1-1.

Table 1-1. The structure of human interpretation.

In articulating tacit understanding, interpretation both discloses inherent implications and discovers unanticipated consequences in the situation. Through interpretation, designers might (a) try to externalize their expectations about a design situation by drawing a sketch and then discover surprises when they explore the sketch. Similarly, they might need to revise their understanding as a result of (b) shifting their focus on a problem and deliberating from alternative perspectives or (c) changing the way they conceptualize an issue and refining the definitions of terms in their language.

The structure of human interpretation carries over to design. The design process is a cycle or spiral of interpretation: (1) some item of the initial preunderstanding—the grasp of the design situation, the perspective for viewing, the language for conceptualizing—is made explicit, reflected upon, and further articulated in new design decisions. (2) This leads to the discovery of unanticipated consequences or contingencies and a new understanding that requires revisions to the understanding of the design problem, its viewpoint, or terminology. (1´) The new understanding then becomes re-submerged into a modified tacit understanding that forms the starting-point for the next iteration of interpretation and design.

The analysis of interpretation in design motivates a theory of computer support. According to this theory, computer support for interpretation in innovative design differs from autonomous software systems for routine design by focusing on supporting or augmenting human activities rather than automating them, because only people have the understanding and creativity required for interpretation. This computer support takes two general forms in order to support the two phases of interpretation:

1.   It provides access to a wealth of information that might be useful as a basis for interpreting new design tasks. This information for reuse is culled primarily from previous design experience, and includes (a) partial representations[2] of design situations, (b) alternative ways of considering tasks, and (c) terminology helpful for conceptualizing problems.

2.   It facilitates the revision of stored information so designers can tailor existing representations to novel problems and can capture innovative designs to extend the computerized knowledge-base and to communicate ideas to collaborators. This plasticity of representation—the ability to mold, form, adapt, alter, or modify the representations—applies to all design knowledge, including (a), (b), and (c) of point (1).

The proposed theory of computer support suggests an approach to building software systems that has been prototyped in a system named Hermes. Hermes is a substrate for building design environments to support interpretation in innovative design. Motivated by the analysis of interpretation, Hermes provides the following features to support reuse and plasticity of representations of each of the three characteristics of interpretation, being situated, having perspectives, and using language (see Table 1-2):

a-1. A persistent hypermedia network for storing partial representations of design situations and for browsing among them.

a-2. Efficient mechanisms for revising the representations (multimedia nodes) and modifying their associations (links).

b-1. A perspectives mechanism that organizes specialized or personal ways of filtering out information of interest

b-2. Procedures for switching perspectives or for creating new ones by merging existing perspectives and modifying their inherited contents in the new one.

c-1. An end-user language that provides useful domain terms, rules for critiquing designs, and queries for displaying stored information.

c-2. The ability to modify or generate new terms, critic rules, and queries or to use the language for defining computations.

Table 1-2. Computer-based mechanisms to support interpreta­tion in design.

Although computers cannot understand things the way people do, they can serve as a computational medium to support people’s interpretive processes. The computer support mechanisms listed in Table 1-2 can augment cooperative design in a number of ways, including:

a-1 As a long-term memory or repository for information that was created in past designing and is now available to be shared by designers using the repository.

a-2 As an external memory for representing and revising designs to see how alternative variations appear.

b-1 As a retrieval mechanism for organizing and managing design knowledge and filtering through just what is relevant.

b-2 As a display mechanism to define new personal and shared views of designs.

c-1 As a linguistic medium for expressing knowledge in a canonical form that can be used for computations by the software.

c-2 As a communication medium to generate new knowledge to be shared with others.

A comparison of Table 1-1 and Table 1-2 shows that the mechanisms of computer support are based on the structure of unaided human interpretation. The computer support is intended to extend the power of designers to operate under conditions of “information overload,” in which it is becoming increasingly difficult to work effectively without the use of computers.

Computer support will inevitably change the practices of collaborative design. This need not be considered harmful—particularly in cases where traditional procedures have become inadequate—if important factors like the characteristics of interpretation are preserved and adequately supported. Computational media have the potential for changing the activities of professionals even more than the media of written language did in the past, because of significant opportunities for the computer to play a computationally active role in organizing, analyzing, displaying, and communicating the information. The ways in which design tasks are accomplished will change dramatically as the computer augments and supports designers to do many of the same tasks they have done unaided in the past, like designing and modifying artifacts.

The proposed theory of computer support for interpretation in design goes to the root of the problem of tacit and explicit understanding. Designers approach their task with a background of skills, know-how, and experience that they are generally not aware of as they design but that is a necessary precondition of their work as trained professionals. For instance, architects have the ability to understand the situations people might face in the buildings they design, they know how to sketch and visualize relationships from the perspectives of different concerns, and they move freely between various frameworks or traditions that provide meaningful languages or metaphors for expressing their insights. Computers have no such tacit preunderstanding; they can only retrieve and manipulate what people have already formulated in explicit propositions or drawings. People and computers are not analogous processors of information. If computers are to support human cognition effectively, then these differences must be understood and taken into account.

By describing the transformation of tacit to explicit human understanding, the analysis of interpretation not only clarifies how human cognition differs from computer information processing, but also suggests how computers can support the way people think. Philosophically, the analysis of interpretation provides the key to a theory of people-centered computer support. Technically, the analysis enumerates the functionality needed for computer support of interpretation in design. Practically, it points out that the process of innovative design and the requirements of collaboration generate both the need for computer support and the sources of explicit knowledge that make it possible. For instance, large, multi-person design projects often confront the problem of information overload, where computers are required to manage volumes of technical knowledge. At the same time, these cooperative design processes naturally articulate much explicit knowledge that could prove useful in subsequent computer-supported design work.

The theory of computer support for interpretation in design is presented in three Parts: in Part I, Chapters 2, 3, and 4 develop the analysis of interpretation in design. In Part II, Chapters 5, 6, and 7 draw the consequences of the problem of tacit and explicit understanding for computer support. In Part III, Chapters 8, 9, and 10 describe how the technical features of the Hermes substrate support interpretation in collaborative design.

The analysis of interpretation is developed by reviewing insightful descriptions of design by design methodologists Alexander, Rittel, and Schön (Chapter 2). Characteristics of design enumerated in that review are then used to guide a study of transcripts of a design session involving a task of lunar habitat design (Chapter 3). The design process—as characterized by design methodology and as illustrated with lunar habitat design—is then conceptualized as a process of interpretation by using Heidegger’s philosophy of interpretation (Chapter 4).

The consequences for computer-based design systems are drawn by further developing the analysis of tacit and explicit understanding in design (Chapter 5), and extending it to include a theory of the computer support of interpretation (Chapter 6). This theory is applied to evaluate traditions of software design environments and design rationale systems; useful techniques in these previous systems are explored and their limitations noted (Chapter 7).

The technical description of computer support for cooperative design describes the central functionality of Hermes. It has a hypermedia knowledge-base to support (a) the representation of design situations (Chapter 8). A virtual copying mechanism provides (b) perspectives on design knowledge (Chapter 9). An end-user language is used for (c) articulating formerly tacit understandings in explicit language (Chapter 10)

The order of presentation in the dissertation corresponds to the process of interpretation. First, in the Introduction and Part I a preunderstanding is sketched to provide a starting point for interpreting the problem of computer support for innovative design. A review of design methodology provides a perspective from which to understand design, formed by merging the perspectives of the three design methodologists. A lunar habitat design project provides a concrete design situation for grounding the developing understanding of design. Heidegger’s philosophy provides a language and conceptual framework for talking about interpretation in design. Second, in Part II this preunderstanding is used to explore possibilities for computer support that are opened up by the preunderstanding. This is accomplished partially by drawing out the theoretical consequences in order to extend the analysis of interpretation in design to include a theory of its computer support. It is further accomplished by discovering the achievements and the limitations of previous software systems in providing the kind of support for design that is called for. Third, in Part III the arrived at understanding allows for a discussion of the Hermes system as an explicit illustration of possible responses to the problem of supporting interpretation in design .

Predecessor systems to Hermes (principally Janus and Phidias) were already headed in the direction that Hermes adopts. Discussions of these earlier design environments made frequent reference to Alexander, Rittel, and Schön, for instance, and insisted on supporting rather than automating design. The theory of computer support for interpretation in design presented in this dissertation extends this approach theoretically and practically. Its focus on interpretation situates its people-centered approach unambiguously in an analysis of human understanding. By providing a coherent perspective for viewing systems to support design, the theory suggests principled extensions to the functionality of design environments, such as those incorporated in the Hermes substrate. It provides an explicit language as a basis for a coherent conceptual framework.

Each section in the remainder of Chapter 1 provides an overview of a chapter of the dissertation. The first three sections each provide an argument for interpreting design as a process of interpretation. The other sections draw the implications of this argument for the computer support of design. The three characteristics of interpretation run through all the chapters. Table 1-3 shows the correspondences between the central themes in the different chapters. These correspondences link the theoretical analysis of interpretation to the operational mechanisms that provide computer support for these characteristics. For the sake of simplicity, the table does not indicate that each of the entries involves both reuse of past information and creative modification, however this is true both for the three characteristics of interpretation and for their corresponding software mechanisms, as already shown in Tables 1-1 and 1-2.

Table 1-3. Correspondences among the chapters.

Note that the three mechanisms of Hermes in Chapters 8, 9, and 10 correspond to the three characteristics of interpretation that permeate and structure the dissertation.

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