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first: 2011-10-12
last: 2011-11-10 |
The title of this subsection is taken from Henrik Gedenryd's thesis on his
cognition oriented analysis of design activities.
[Gedenryd 1998] His analysis will be recognized by most people who are, or
have been, involved in design processes.
He positions a practical approach against the traditional, intellectual,
what he calls \emph{intra-mental} approach. With
intra-mental
cognition he indicated the view of cognition as a process that is contained
entirely within the mind, and which is performed by the mind alone,
cognition being strictly isolated and separated from action, perception, and
every aspect of the surrounding world, be it material, social or cultural.
[id.: 7-8]
Information Processing Theory proved to be inadequate as a fundamental
theory of cognition. The standard diagnosis is that its problems are located
in the computer model of the mind and the symbolic view of cognition.
According to Gedenryd this is not the crucial defect. Intra mentality is the
culprit that caused the problems in explaining cognitive processes. One of
the reasons that this key issue has not been recognized is the fact that it
is not stated explicitly. [id.: 9]
In contrast to the intellectual perspective, there is an alternative
approach where cognition is seen as fundamentally practical by nature. He
then refers to Husserl, Heidegger and pragmatism, in particular as worked
out by John Dewey. [id.: 10]
In
Practical Reasoning and Engineering Jesse Hughes reviews some more
or less formalized concepts.
Engineering is successful to the extent that it provides means to satisfy
our needs and desires, i.e. if it is successful as a method of practical
reasoning. The final end of the design process is the technical artifact.
Artifacts - both types and tokens - are evaluated in terms of their
effectiveness and reliability, that is in terms of their efficacy as means.
[Hughes2009: 375]
He argues that instrumentalism is eminently applicable as a theory of
practical reasoning in the process of engineering design. (id.: 376)
The fundamental thesis of instrumentalism is that practical reasoning
consists of nothing but \emph{means end} (short for \emph{means to an end})
reasoning.
Hughes then refers to the more formalized methodologies as for example
described in Dym and Little. In his section \emph{Syllogism and means} a
formal structure is specified of a means end reasoning as found in
(Curchland, 1970):
>
I want φ
>
Doing α is a way for me to bring about
φ under these
circumstances.
>
There is no other way to bring about φ now which is preferable to me
than doing
α.
There is no sufficient reason for me not to bring about
φ under these
circumstances.
Therefore, let me do α
However, designers do not work according to such strict logical schemes! In
his chapters
The master plan and
The failure of design
methods of his thesis Gedenryd gives a critical analysis of design
methodologies because the conventional theories describe the wrong concepts.
He considers these as belonging to the same family of rationalities as
described by Pappus way back in Alexandria in the fourth century. Pappus
described a method, in the domain of mathematics, of how to analyze a new
theorem first down to basic axioms in order to use the same steps to
synthesize the theorem by building up steps from axioms. G.Polya in his
How to Solve It refers to Pappus' concepts as a general method to
solve problems and to create solutions. Since the middle of the last
century, this methodological concept has been generally adopted and has been
worked out in various ways. These design methods have been applied on large
scale by NASA and military-type technology projects. This model became also
well accepted in the area of software engineering.
Gedenryd refers to several authors who reject these methodological concepts
as these would only be applicable to simple routine design work.
[Gedenryd 1998: 59-62) He states that the fundamental mistake, made by
Pappus first, and consequently made by all who worked out the concept into
design methodologies, is that the method describes the products, not the
processes. [id.: 62]
Also Bryan Lawson, in \emph{How Designers Think, the design process
demystified}, evaluates various design methods and design process ``maps".
[Lawson 1980: 33)] The common idea behind these methods and maps is the
assumption of a sequence of distinct and identifiable activities can be
applied. He concludes that:
Unfortunately these assumptions turn out
to be rash.
The start of a design as an action to solve a problem, has been criticized
by many as Gedenryd emphasized with a couple of references. Donald Sch\pol
on coined the term \emph{problem setting} to indicate that the
identification of a problem as a first step should not be seen independent
from the solution. Or put more sharply, designers create problems first.
In
Educating the Reflective Practitioner Donald A Sch
ön made a
distinction between technological activities in activities on the high
grounds and between activities in the swamps.\fn{Donald Sch
ön studied
philosophy, Ph D on John Dewey's theory of inquiry, wrote with the
experience of a working life as an industrial consultant, technology manager
and teacher in a professional school. [Schoen 1983:vii) The
activities on the high grounds can be ``handled" by the book. The activities
in the swamps are the more complex, unique ones, where various elements, not
all fully known, play a role and judgment based on considerations of various
aspects including economics and risks is required. [Sch
ön
1988a: 8)
He worked in a team that observed and trained professionals in design. Based
on their observations they recognised that inherent, in the practice of
unusually competent professionals lies a core of artistry.
[This] artistry is an exercise of intelligence, a kind of knowing, though
different in crucial respects from our standard model of professional
knowledge. It is not inherently mysterious; it is rigorous in its own terms;
and we can learn a great deal about it by carefully studying the performance
of unusually competent performers.
Some different competences were observed:
There are an art of problem framing, an art of implementation, and an art of
improvisation, all necessary to mediate the use in practice of applied
science and technique. [Schön 1988a: 13]
Teachers say:
that there are essential ``covert things" that can never be explained either
the students gets them in the doing, or he does not get them at all. [id.:
82]
Sch
ön reported that they analyzed the characteristics of the
architectural design, but claimed these characteristics to be equally
applicable in other areas.
The designers were asked to give as much explanation as possible of what
they were thinking, considering and doing. Sketches were collected and the
sessions were taped. Although the design processes and considerations were
quite different a number, of more or less common elements could be detected.
All the participants reasoned their way from premises to conclusions. Their
premises took the form of design rules, sometimes explicitly stated, more
often implicitly understood; their conclusions took the form of judgments
about the desirable or undesirable directions of designing or decisions
about design moves. Rules were used but never in an absolute way, exceptions
were easily made.
Especially references and experienced archetypes guide the selection of
rules, but they are also base for the challenging of the rules. Functional
types, used to provide information necessary for the application of design
rules, supply the intermediate premises of reasoning.
Sch
ön opposed the instrumental model as a structured way of designing.
Instead, he claimed design should be seen as a kind of art. With examples
from workshops he argued that the art can improve by experience, by being
coached, but not without a certain amount of talent, to be there as a
starting predisposition. [Schoen 1988a: 80-99]
The reference model defined in section 3.3. is based on the redesigning of
existing functional artifacts. System design does not always start with one
or more specific examples, but with a System Requirements Specification
(SRS) for new applications.
The design of larger systems in general will show a combination of what
usually is indicated as
top-down and
bottom-up design
processes. The top-down approach starts with a split of required functions
into subfunctions. During this split, system designers already have a notion
of the kind of subsystems and components that will be available or are
feasible to be realized. Subfunctions in general will have a coherent
functional structure with welldefined, (or definable during the later
phases) interfaces. That does not necessarily mean they are closed physical
units. For instance, complex subsystem functions in general are to be
considered as a conglomerate of sub functions.
These subfunction can be allocated as welldefined spatial units, but more
often the function is distributed over the complete system.
For instance, the brake system of a car should from a functional design
point of view realize the brake function. However, the requirements
specification is related to the overall specification of the car. The design
specification is related to other characteristics of the car and should
specify the allocation of functional requirements to user interfaces and the
the brake controls, the servo unit, the control indicators, the hydraulic
system etc). Each of these subfunctions should be mechanically positioned.
System design also requires some kinds of basic capabilities to have an
overview of complexity and a tacit knowledge of the functions and additional
characteristics of system modules.

DITT
model