2.3.    Schön: Tacit Knowing and Explicit Language

Schön argues in his seminal work, The Reflective Practitioner (1983), that much design knowledge is tacit, rather than being rule-based. He views the design process as a dialogue-like interaction between the designer and the design situation, in which the designer makes moves and then perceives the consequences of these design decisions in the design situation (e.g., in a sketch). The designer manages the complexity that would be overwhelming if all the constraints and possibilities were formulated as explicit symbolic rules by using professionally-trained skills of visual perception, graphical sketching, and vicarious simulation. Note that these skills by-pass the process of analyzing everything into primitive elements and laying it out in words and propositions.

Schön recently addressed the question of computer support for design in an article descriptively entitled Designing as Reflective Conversation with the Materials of a Design Situation (Schön, 1992). He argued for a necessarily limited role for computers in design because one of the most important things that designers do is to construct the design situation itself. Not only is this something that computers cannot do by themselves, but it also precludes programmers of computer systems from pre-defining a generic design situation for the computer, prior to the involvement of the designer with the task.

To illustrate his claim that designers “construct” the design situation, Schön reviews an experiment in which several experienced architects are shown a 14-sided, dimensioned polygon with door locations indicated, and asked to design a library with that shape as its footprint. One architect saw the figure as two Ls back to back; another saw it as three pods surrounding a middle; a third saw it in terms of simple end entrances and complex middle entrances. Clara, another subject, discovered a five foot displacement in the layout which complicated the spatial relationships considerably for her. (See Figure 2-2, below.)

Schön concludes from these and other studies that designers construct the problem by seeing the situation as defined in a certain way:

In one sense, the 5 ft displacement that Clara noticed is there to be discovered. However, not everyone who tried the library exercise discovered it. Clara did. She noticed it, named it, and made a thing that became critically important for her further designing. In this sense, her treatment of the library exercise shows her not only discovering but constructing the reality of a design situation. For designers share with all human beings an ability to construct, via perception, appreciation, language, and active manipulation, the worlds in which they function. . . . Every procedure, and every problem formulation, depends on such an ontology: a construction of the totality of things and relationships that the designer takes as the reality of the world in which he or she designs. (Schön, 1992, p.9)

 

Figure 2-2 . Four interpretations of the library.

Here the library is displayed in Hermes in four interpretive contexts, corresponding to the views of the four architects in Schön's study.

 

 

What is Clara constructing here? She is not constructing the physical artifact (the actual library or even the drawing of it), but an interpretation of the problem situation as having certain crucial features, certain semantics, for her. Her awareness of the five foot displacement becomes increasingly explicit. She names it as a feature of the task and thinks about its relationship to possible solutions. Of course, the displacement was always physically present in the drawing, and the other architects may have had a subsidiary awareness of it. Maybe if they were questioned they would retroactively even be able to focus on it. However, it was not a focus for their designing the way it was for Clara's; they focused on other structures. Clara focused on the displacement. It became a problem for her. She reflected upon it as a central constraint of the design situation: she construed the situation in terms of this particular problem. Perhaps it presented an opportunity for her to do something with the library that she wanted to do; or perhaps it was a characteristic kind of feature she often exploited; or perhaps it stood in the way of her taking an accustomed approach. Whatever the details, she came to the task in her own characteristic way and constructed a design situation that differed essentially from what each of the other architects constructed. Each architect interpreted the given problem as a different task.

According to Schön, it is essential to recognize that the designer brings a creative constructive vision to the task. The problem of the library—the structure of the layout—is not explicitly given in the sense that an exhaustive specification of it could be given even in principle, but is experienced primarily in the mode of tacit subsidiary awareness (Polanyi, 1962). Nor does the designer impose a standard structure for interpreting the task. Rather, the designer approaches it with certain anticipations, conceptualizations, and background knowledge. Then the designer interacts with it to discover the basis for an understanding in terms of which the situation is framed or constructed. By attending to the displacement that others had ignored and naming it explicitly, Clara made it a crucial component of her design situation.

Schön's description of “construction” is very similar to Merleau-Ponty's concept of creative discovery, which is dependent on both the concrete individual and the specific task in their dialogical relation. Schön was undoubtedly influenced during his post-doctoral philosophy studies in Paris by Merleau-Ponty, the leading French philosopher teaching there at the time. Merleau-Ponty's Phenomenology of Perception (Merleau-Ponty, 1945) is perhaps the best analysis of Heidegger's philosophy (see Chapter 4 below) in terms of how we perceive our world. For Merleau-Ponty, the interpretive situation is neither simply objectively given nor subjectively represented, but creatively discovered. The dialectic of anticipatory framing and tentative setting of the object of perception as such and such a thing is elevated to an ontological principle by him at the same time as it is grounded in our corporeality as embodied perceivers. Perhaps more explicitly than any one else, Merleau-Ponty formulated a philosophy that explored the interplay of subjectivity and objectivity. By recognizing in detail how our body spans the subject-object dichotomy, he resolved at an abstract level the conflict that pervades late twentieth-century thought, including the design theory of Alexander, Rittel, and Schön. (The relevance of this conflict between the objectivity of artifacts in the world and the subjectivity of our interpretive perspectives for the question of computer support for design will be discussed at the conclusion of this chapter.)

Schön reviews other experiments that show that designers also construct the materials, site, and relationships in a similar way to how Clara constructed the crucial patterns of the project. In this sense, then, there is no given design problem that is explicitly and exhaustively defined before the designer comes to it. Correspondingly, there can be no well-defined problem space for the designer (or for some automated version of the designer) to search through methodically. Rather, the designer's subjective, personal or intuitive appreciations shape the problem by constructing its patterns, materials, and relationships. The design project is solved by the designer experimenting with tentative moves within the constructed design situation and discovering the consequences of those moves.

Clara made explicit the presence of the five foot displacement in the library footprint. As she works further on the library design, her awareness of the displacement may fade away, although it will have left its mark in the way she sees the structure of the building. This is one example of tacit knowledge becoming explicit for awhile during the design process, and then re-submerging into tacit, subsidiary awareness.

The movement from tacit to explicit understanding is an important and ubiquitous phenomenon, which Schön analyzes in more general terms in The Design Studio (Schön, 1985). Here he talks about the movement from knowing-in-action to reflection-in-action. For him, human action embodies tacit forms of knowledge: knowing how to physically do something without thinking about it or necessarily knowing that it may correspond to certain rules:

To begin with, the starting condition of reflection-in-action is the repertoire of routinized responses that skillful practitioners bring to their practice. This is what I call the practitioner's knowing-in-action. It can be seen as consisting of strategies of action, understanding of phenomena, ways of framing the problematic situations encountered in day-to-day experience. It is acquired through training, or through on-the-job experience. It is usually tacit, and it is delivered spontaneously, without conscious deliberation. (p.24)

Schön's concept of knowing-in-action should be contrasted with the rationalist view of human action, which persists strongly into recent cognitive science. Rationalism (e.g., the tradition of Plato and Descartes) assumes that the basis of action is rational thought, that our behavior is caused by symbolic representations in our minds that could be articulated in propositions in language. Even in cases where we are not consciously aware of rational thought, it is argued, knowledge is at work unconsciously or in a “compiled” form and it could (at least in principle) be made explicit either by introspection of one's own motivations or by observation of rule-like regularities. Cognitive science makes the analogy between minds and software: our behavior, like that of a computer, is a matter of following computational rules that could be spelled out as an algorithm.

Polanyi, from whom Schön borrows an analysis of tacit knowledge, turns the traditional relationship between tacit knowing and rational thought around: “Tacit knowledge is more fundamental than explicit knowledge: we can know more than we can tell and we can tell nothing without relying on our awareness of things we may not be able to tell” (Polanyi, 1958, p. x). Our ability to use language and rational thought depends on more primordial skills and practices that cannot be clearly and exhaustively explicated: “We may say in general that by acquiring a skill, whether muscular or intellectual, we achieve an understanding that we cannot put into words and which is continuous with the inarticulate faculties of animals” (p.90). The priority of the tacit over the explicit does not mean that tacit knowledge is somehow better or more valuable, just that it is the precondition in terms of both ontogeny and phylogeny. That is, for an individual person to articulate an idea, he or she must previously have possessed a tacit background understanding that led to the idea and grounded its meaning. Similarly, for the human species to have developed sophisticated language and rational thought, it must have already evolved tacit forms of understanding such as those based on episodic (case-based) and mimetic (imitative) memory. Rational thought is still what distinguishes people from other animals, but that does not mean that rationality can exist without a foundation in tacit knowing-in-action.[1]

Polanyi provides the most concrete and detailed examination of tacit knowledge available. His analysis is strikingly close to that of Heidegger (see Chapter 4), as Polanyi acknowledges in his 1964 Preface: “All understanding is based in our dwelling in the particulars of that which we comprehend. Such indwelling is a participation of ours in the existence of that which we comprehend; it is Heidegger's being-in-the-world” (p. x). Unfortunately, Polanyi tends toward relativism, ending with a concept of “personal knowledge” that is too little grounded in the objectivity of a shared world. He emphasizes that everyone can have their own personal interpretations (assuming certain constraints of consistency, etc.), but lacks the sense of our embodiment (Merleau-Ponty) or situatedness (Heidegger) in a shared world, common traditions, social practices, and public language. (Compare Heidegger’s views on a shared world in Section 4.2.)

Polanyi distinguishes focal and subsidiary awareness. His view of this is derived from the distinction between foreground and background in classical Gestalt psychology. Applying these terms, one could say that when Clara had a focal awareness of the five foot displacement, she also had a subsidiary awareness of the floor plan as a whole. It was only on the basis (background) of her tacit understanding of the problem as a whole (the floor plan) that the displacement could be taken as important and be understood as having certain implications—causing certain problems for the design. But, given this tacit knowledge of the whole, the focal part became the meaning of the whole: the design problem became a problem of resolving the issue of the displacement.

One can, according to Polanyi, only be focally aware of one thing at a time. When we switch our attention to something of which we have hitherto been subsidiarily aware, it loses its previous meaning. Consider the following three phases of Clara's attention:

Phase 1. She focuses on the plan as a whole, being only subsidiarily aware of the displacement (the way the other architects remained at best subsidiarily aware of it).

Phase 2. She focuses on the displacement. Now the displacement becomes the meaning of the whole floor plan. She becomes more explicitly aware of the displacement and starts to explore its details and implications. However, she can never achieve absolute explicit knowledge of the displacement issue because it involves and relies upon her tacit understanding of the general background problem.

Phase 1'. She returns her attention to the floor plan in general. Now her knowledge of the displacement becomes tacit once more. Of course, this tacit knowledge is much richer then it was originally, when she barely noticed it like the other architects. Now it can play an important role in her thinking about the floor plan.

How does Clara make these transitions? Why does the focus of her attention shift during the design process? Schön proposes an interesting theory of breakdowns to account for the shift from tacit knowing-in-action to an explicit focus and reflection. He argues that we can go along just doing what we are skilled at doing without much need for conscious thought. We are pretty much immersed in the doing, and any use of explicit language is more in the way of commentary than figuring things out. This can continue comfortably until we hit a problem that our skill cannot automatically resolve. Then, tacit doing suddenly breaks down and we have to think through the problem, explicitly focusing on the problem area:

Sometimes, however, there are surprises. These take the form of unanticipated events which do not fit existing understandings, fall outside the categories of knowing-in-action. . . .

There is a demand for reflection, through turning to the surprising phenomena and, at the same time, back on itself to the spontaneous knowing-in-action that triggered surprise. It is as though the practitioner asked himself, “What is this?” and at the same time, “How have I been thinking about this?”

Such reflection must be at least in some degree conscious. It converts tacit knowing-in-action to explicit knowledge for action. (Schön, 1985, p.24)

We become aware of the problem and of what we have been doing that led us to the problem.

For instance, Clara was sketching in phase 1 above. She was exploring the approaches to the different entrances in the floor plan by drawing paths that users of the library would need to take. She was using her tacit architectural skills of sketching and vicariously moving through the spaces of the drawing. As she approached one of the interior doors, Clara suddenly remarked, “It's interesting that there's a five foot displacement here. I'm beginning to get more of a sense of those dimensions” (Schön, 1992, p.8). In the time it took her to say this, Clara passed through phase 2 and into phase 1'.

As Schön's commentary to this typical moment analyzes it, this was an instance of surprise or breakdown, which stimulated successful reflection-in-action. Clara had been pursuing a problem about the approach to the library. As she traversed one wall in her imagination she was surprised to find that it was longer than all the other (equal length) walls. Glancing across the interior, she saw the five foot jog in the opposite wall. These newly observed facts presented a problem for her attempt to find a comfortable approach to the building because they changed her understanding of the overall configuration. They showed that certain walls of interest were actually longer than other walls. Focusing on the five foot segments that made this difference gave new meaning to the whole building. As a trained architect, Clara could reflect on her discovery quickly, understand its significance and incorporate it in what she had been doing before.

Schön stresses that he is concerned with the form of reflection that actually takes place in the phase 2 moment of problem-solving—not what takes place retroactively long after the problem has been solved and the engagement with the process is broken. For Schön, reflection-in-action “must take place in the action-present—the period of time in which thinking can still make a difference to the outcomes of action. It has a critical function, questioning and challenging the assumptional basis of action, and a restructuring function, reshaping strategies, understanding of phenomena, and ways of framing problems” (Schön, 1985, p.25).

As a result of this moment of breakdown-reflection-repair, Clara's understanding of the overall problem has changed, as she immediately remarks. This does not mean she has an absolute and fully explicit understanding of the problem, but rather, as she puts it, she is “beginning to get more of a sense of those dimensions.” The fact that she goes on to explore other issues and transfers her attention away from the displacement does not mean that the knowledge she gained from her momentary reflection-in-action is gone. It has just become subsidiary and tacit. According to Schön's description, later on in her designing, when she considered the entrance on the other side next to the five foot jog, “her discovery of the five foot displacement reemerges, and becomes central to her rethinking of spaces for circulation and use” (Schön, 1992, p.8).

Schön argues that a computer program cannot on its own construct a design situation the way an architect does, picking out, naming, and focusing upon critical patterns, materials, and relationships. The “construction” of a situation requires evolving a representation for it through the dialectic of creative-discovery or reflective conversation. It requires a subtle interplay between tacit knowing-in-action and more explicit reflection-in-action. To the extent that the role of a designer includes applying intuitive, perceptual, and linguistic skills to view the situation creatively and to converse with it reflectively, a computer cannot do what a human designer does. Assuming that Schön is correct that these skills are necessary for real design, a computer can also not accomplish the design task using alternative methods to those used by humans, because computer programs as we know them are ultimately based on predefined representations of fixed and strictly delimited ontologies. Computer programs for design are therefore limited to solving problems in well-defined “microworlds” (Papert, 1980) in which the framing of new problems is trivial, or else to working with human designers to augment their tacit skills and to allow them to define the perspectives and concepts in terms of which tasks are to be undertaken. Artificial intelligence (AI) projects have usually followed the microworlds option, trying to capture knowledge of a delimited domain in a symbolic representation that facilitates algorithmic computations. Schön calls for the alternative option of providing tools for people to define for themselves (within a computer system) representations of their own constructions or personal interpretations.

Ways must be found to support the interplay of tacit knowledge-in-action with more explicit reflection-in-action, which re-submerges into tacit awareness when the action-present passes. For a computer to process data, all information must be explicitly stated for it. A computer cannot slip facilely between the tacit and the explicit, the way people move from knowing-in-action to reflection-in-action. A person must translate the tacitly perceived world into a representation that makes explicit for the computer the person's partially implicit interpretation. Schön’s theory of how designers are constantly making aspects of their implicit understanding explicit suggests that the computer should capture these explicit representations during the “action present” in which they can be most easily articulated. The implications of this for a theory of computer support are taken up in Chapter 6.

Three Perspectives on Design. The three writers just considered all present views of design as a process of interpretation. Alexander's tack of structural decomposition is one approach to interpreting a problem. For instance, the four architects in Schön's experiment interpreted their design situation differently by decomposing the library floor plan in four different ways: into a pair of “L” shapes, three pods around a middle space, a combination of simple and complex entrances, or a set of equal length walls complicated by a five foot displacement. Alexander recognizes how subtle even an objective seeming interpretation of a design can be, such as supporting people's tendency to want a view from their office desk. Finally, Alexander tries to provide a pattern language that people can use to articulate personal or group interpretations of buildings.

Rittel views the problems of planning and design as wicked problems largely because the participants in these processes bring conflicting interpretations to bear: they have different motivations, theoretical frameworks, and commitments. The notion of design as deliberation is an attempt to bring these differing interpretations into contact with each other in fruitful ways. Computer systems can serve as supportive crutches for such processes.

Schön emphasizes the variety of interpretations that an individual designer can pass through during a design session, as well as the differences in interpretation that different people are likely to come up with. One always sees something as something. This involves seeing a whole that one is subsidiarily aware of as meaningful in terms of a detailed aspect that is the momentary focus of awareness. When the evolving design artifact surprises the designer with something that stumps the interpretation projected by the designer's skilled, tacit knowing, then the designer is forced into a mode of reflection that transforms the interpretation. Interpretations are neither fixed nor arbitrary. They grow out of the traditions in people's backgrounds and they adapt to the constraints of the world to which they are applied.

These three writers provide important arguments about the three features of the process of design proposed in Chapter 1. They stress the roles of the situation, alternative perspectives, and explicit articulations. Furthermore, each of these is seen as essentially evolving, so that past understandings are built upon and modified. Despite their strong differences, each of these design methodologists describes design as a process of situated, perspectival, linguistic interpretation. Their emphases are different.

a. Situation. Alexander presents a strong case for deriving the interpretations in terms of which a design situation is to be construed from an analysis of the specifics of the problem. He claims that one must analyze the structure of the problem into patterns of components that are relatively independent. In a sense, this decomposition of the problem is a step towards solving it. In that sense, it is similar to Rittel's claim that the problem framing is inseparable from the problem solving. Schön echoes that sentiment by showing how the designer's understanding of the problem emerges from the dialogue with the design situation, which explores potential solutions.

b. Perspective. Rittel is the one who most emphasizes the uniqueness of the perspectives that designers bring to their work. Designers are as different as are problem situations; they have individual motivations, backgrounds, and commitments. At the same time, the factors that make people different each have a shared basis in their cultures, schools of thought, languages, and so on. While their perspectives may be irreconcilable in some ways, collaboration can critique and synthesize individual opinions to establish areas of consensus and to move beyond unreflective idiosyncrasies. Alexander recognizes the importance of different cultural traditions and tries to compile and organize patterns from diverse architectural traditions in order to provide a clearer basis for personal languages of designing. For Schön, individual interpretations can arise in the design process itself, regardless of personal differences among designers. In fact, a given designer will constantly be changing perspectives on the problem during the countless phases of the design process.

c. Language. Schön talks the most about how explicit interpretations emerge through articulating tacit knowing in language, and then re-submerge into the tacit. Alexander talks in much this way about the need for both intuition and analysis. For him, intuition is also associated with design practice. Practice is the necessary tacit element that is likely to be missing from considerations of explicit methodology. Rittel's emphasis on the role of personal prejudice recognizes the tacit basis of argumentation; yet his proposal of Ibis is very much a move toward making deliberation even more explicit than it is in less structured formats.

Computer support. Alexander, Rittel, and Schön have all taken seriously the question of computer support for design. They each wanted to use computers for their favorite part of the design process. Alexander used computers to analyze the decomposition of structures. Rittel used them to support the Ibis system of argumentation. Schön recommended using computer-based design assistants to create an environment in which a designer could explore design microworlds, reflect on knowledge, and enhance skills. None of them advocated an automated expert system approach. Alexander felt that such an approach led to people playing with computers like toys, divorced from the concerns of practicing designers. Rittel thought such systems would incorporate “freeze-dried prejudice” rather than stimulating the deliberative process of design. Schön argued that design requires human skills that computers could not duplicate, imitate, or replace by themselves.

Where Alexander was still struggling to maintain a sense of the possibility of objective methods in the face of problems that were becoming apparent in the 1960's, Rittel was formulating a clear call in the 1970's for an alternative use of computers to support human designing. In particular, he proposed supporting deliberation among opposed interpretive perspectives. Then in the 1980's Schön was able to describe the interplay between the human designer and the materials of the design situation as an interpretive dialogue. It remains for the 1990's to implement adequate computer support for this process of interpretation in design.

Objectivity and subjectivity. One could interpret Alexander and Rittel as occupying opposite ends of the spectrum. Alexander seems to long for the objectivity of mathematical decomposition analysis, empirical hypothesis verification, and a distillation of eternal patterns for building. Rittel, in contrast, stresses that similarities of pattern are a matter of interpretation and that all judgments are ultimately grounded in subjective prejudice. But first of all, there are historical differences. The late sixties, which separated most of the writings of Alexander and Rittel reviewed here, saw the widespread crumbling of faith in unified, objective science and in the mathematical methods of operations research.[2] And secondly, neither Alexander nor Rittel hold to simple, easily characterized views.

The question of how knowledge is objective and how it is subjective is closely related to whether design can be computerized or not. Certainly the expert system approach is one that assumes that design knowledge can be formulated in an objective way. The paradigm here is that one finds an expert who has somehow learned the knowledge of the relevant design domain: applicable regulations, rules of thumb, accepted wisdom, tricks of the trade, prototypical solutions, standard approaches. Through interview techniques, the expert's knowledge is made explicit and captured in a large set of rules, which are entered into the computer. Then, the specification for a problem in the domain is entered with sufficient detail and with all the relevant information so the computer can compute a solution that satisfies the specification by applying the set of rules to the specified starting conditions and goals. This approach should be contrasted with the view of design as interpretation. While it may work in certain narrowly-defined and well-understood domains, the expert system approach ignores the features of design that Alexander, Rittel, and Schön have argued are decisive for most innovative design work. Design knowledge cannot be formulated in abstract rules because it is dependent upon the situation, perspective, and language which are brought to bear in essentially unique concrete instances of interpretation. The rules of autonomous software systems can only work in narrowly defined realms in which a standard interpretation is accepted.

The design methodologists just reviewed present a strong case that computer systems should enable designers to define their own understanding of the structure of the design problem, to formulate their own perspectives based on traditional views, and to articulate their tacit knowledge in increasingly explicit forms. In this way, personal or group interpretations can build upon shared domain knowledge but also go beyond it. While a computer-based system can support such activities, it cannot do them without human participation. This is where the subjective aspect enters. As long as design is conceived as involving subjective aspects, it cannot be automated. Computers may be able to keep track of interpretive perspectives and even help to elicit tacit knowledge or subjective views, but computers cannot interpret. Nor can knowledge corresponding to interpretations be entered into computer systems in advance, the way that standard domain knowledge can (under the most favorable of conditions). By definition, domain knowledge is general and can be catalogued (although never exhaustively since it includes tacit background knowledge that cannot all be made entirely explicit). In contrast, interpretations are by nature innovative and go essentially beyond the standard domain traditions upon which they build—hence their characterization as “subjective”. They can only be added to the computer knowledge base post hoc, in order continuously to expand the base upon which future interpretations can grow.