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 DESCRIPTION:
Written by the man who coined the term "paradigm shift" this
book describes the process and the end result. In essence paradigm shift is a relatively
abrupt, fundamental change in the way that a specific conceptual world view is defined.
The revisions tend to supplant earlier views that have served the needs of workers in
specific fields, but have eventually proven to be inadequate. The replacement of Ptolemy's
geocentric system by the heliocentric system of Copernicus and the discovery of
oxygen are
two historical examples used to shed light on the nature of its workings.
EXCERPT:
From Chapter VI. Anomaly
and the Emergence of Scientific Discoveries
Our
final example of scientific discovery, that of the Leyden jar, belongs to a
class that may be described as theory-induced. Initially, the term may seem
paradoxical. Much that has been said so far suggests that discoveries
predicted by theory in advance are parts of normal science and result in no
new sort of fact. I have, for example, previously referred to the
discoveries of new chemical elements during the second half of the
nineteenth century as proceeding from normal science in that way. But
not all theories are paradigm theories. Both during pre-paradigm
periods and during the crises that lead to large-scale changes of paradigm,
scientists usually develop many speculative and unarticulated theories that
can themselves point the way to discovery. Often, however, that
discovery is not quite the one anticipated by the speculative and tentative
hypothesis. Only as experiment and tentative theory are together
articulated to a match does the discovery emerge and the theory become a
paradigm.
The discovery of the Leyden jar
displays all these features as well as the others we have observed
before. When it began, there was no single paradigm for electrical
research. Instead, a number of theories, all derived from relatively
accessible phenomena, were in competition. None of them succeeded in
ordering the whole variety of electrical phenomena very well. That
failure is the source of several of the anomalies that provide background
for the discovery of the Leyden jar. One of the competing schools of
electricians took electricity to be a fluid, and that conception led a
number of men to attempt bottling the fluid by holding a water-filled glass
vial in their hands and touching the water to a conductor suspended from an
active electrostatic generator. On removing the
jar from the machine and touching the water (or a conductor connected to it)
with his free hand, each of these investigators experienced a severe
shock. Those first experiments did not, however, provide electricians
with the Leyden jar. That device emerged more slowly, and it is again
impossible to say just when its discovery was completed, The initial
attempts to store electrical fluid worked only because investigators held
the vial in their hands while standing upon the ground. Electricians
had still to learn that the jar required an outer as well as an inner
conducting coating and that the fluid is not really stored in the jar at
all. Somewhere in the course of the investigations that showed them
this, and which introduced them to several other anomalous effects, the
device that we call the Leyden
jar emerged. Furthermore, the experiments that led to its emergence,
many of them performed by Franklin, were also the ones that necessitated the
drastic revision of the fluid theory and thus provided the first full
paradigm of electricity.11
To a greater or lesser extent
(corresponding to the continuum from the shocking to the anticipated
result), the characteristics common to the three examples above are
characteristic of all discoveries from which new sorts of phenomena
emerge. Those characteristics include, the previous awareness of
anomaly, the gradual and simultaneous emergence of both observational and
conceptual recognition, and the consequent change of paradigm categories and
procedures often accompanied by resistance. There is even evidence
that these same characteristics are built into the nature of the perceptual
process itself. In a psychological experiment that deserves to be far better
known outside the trade, Bruner and Postman asked experimental subjects to
identify on short and controlled exposure a series of playing cards.
Many of the cards were normal, but some were made anomalous, eg., a red six
of spades and a black four of hearts. Each experimental run was
constituted by the display of a single card to a single subject in a series
of gradually increased exposures. After each exposure the subject was
asked what he had seen, and the run was terminated by two successive correct
identifications.12
Even on the shortest exposures
many subjects identified most of the cards, and after a small increase all
the subjects identified them all. For the normal cards these
identifications were usually correct, but the anomalous cards were almost
always identified, without apparent hesitation or puzzlement, as
normal. The black four of hearts might, for example, be identified as
the four of either spades or hearts. Without any awareness of trouble,
it was immediately fitted to one of the conceptual categories prepared by
prior experience. One would not even like to say that the subjects had
seen something different from what they identified. With a further
increase of exposure to the anomalous cards, subjects did begin to hesitate
and to display awareness of anomaly. Exposed, for
example, to the red six of spades, some would say: That's the six of spades,
but there's something wrong with it—the black has a red border.
Further increase of exposure resulted in still more hesitation and confusion
until finally, and sometimes quite suddenly, most subjects would produce the
correct identification without hesitation. Moreover, after doing this
with two or three of the anomalous cards, they would have little further
difficulty with the others. A few subjects, however, were never able
to make the requisite adjustment of their categories. Even at forty
times the average exposure required to recognize normal cards for what they
were, more than 10 percent of the anomalous cards were not correctly
identified. And the subjects who then failed often experienced
acute personal distress. One of them exclaimed: "I can't make the
suit out, whatever it is. It didn't even look like a card that time. I
don't know what color it is now or whether it's a spade or a heart.
I'm not even sure now what a spade looks like. My God!"13
In the next section we shall occasionally see scientists behaving this way
too.
Either as a
metaphor or because it reflects the nature of the mind, that psychological
experiment provides a wonderfully simple and cogent schema for the process
of scientific discovery. In science, as in the playing card
experiment, novelty emerges only with difficulty, manifested by resistance,
against a background provided by expectation. Initially, only the
anticipated and usual are experienced even under circumstances where anomaly
is later to be observed. Further acquaintance, however, does result in
awareness of something wrong or does relate the effect to something that has
gone wrong before. That awareness of anomaly opens a period in which
conceptual categories are adjusted until the initially anomalous has become
the anticipated. At this point the discovery has
been completed. I have already urged that that process or one very much like
it is involved in the emergence of all fundamental scientific
novelties. Let me now point out that, recognizing the process, we can
at last begin to see why normal science, a pursuit not directed to novelties
and tending at first to suppress them, should nevertheless be so effective
in causing them to arise.
In the development of any
science, the first received paradigm is usually felt to account quite
successfully for most of the observations and experiments easily accessible
to that science's practitioners. Further development, therefore,
ordinarily calls for the construction of elaborate equipment, the
development of an esoteric vocabulary and skills, and a refinement of
concepts that increasingly lessens their resemblance to their usual
common-sense prototypes. That professionalization leads, on the one
hand, to an immense restriction of the scientist's vision and to a
considerable resistance to paradigm change. The science has become
increasingly rigid. On the other hand, within those areas to which the
paradigm directs the attention of the group, normal science leads
to a detail of information and to
a precision of the observation—theory match that could be achieved in no
other way. Furthermore, that detail and precision-of-match have a
value that transcends their not always very high intrinsic interest.
Without the special apparatus that is constructed mainly for anticipated
functions, the results that lead ultimately to novelty could not
occur. And even when the apparatus exists, novelty ordinarily emerges
only for the man who, knowing with precision what he should expect, is able
to recognize that something has gone wrong. Anomaly appears only
against the background provided by the paradigm. The more precise and
far-reaching that paradigm is, the more sensitive an indicator it provides
of anomaly and hence of an occasion for paradigm change. In the normal
mode of discovery, even resistance to change has a use that will be explored
more fully in the next section. By ensuring that the paradigm will not
be too easily surrendered, resistance guarantees that scientists will not be
lightly distracted and that the anomalies that lead to paradigm change will
penetrate existing knowledge to the core. The very fact that a
significant scientific novelty so often emerges simultaneously from several
laboratories is an index both to the strongly traditional nature of normal
science and to the completeness with which that traditional pursuit prepares
the way for its own change.
11 For various stages of the Leyden jar's
evolution see I. B. Cohen, Franklin and Newton: An Inquiry into Speculative
Newtonian Experimental Science and Franklin's Work in Electricity as an
Example Thereof (Philadelphia, 1956), pp. 385-88, 400-406, 452-67, 506-7.
The last stage is described by Whittaker, op, cit., pp. 50-52.
12 J. S. Bruner and Leo Postman, "On
the Perception of Incongruity: A Paradigm," Journal of Personality,
XVIII (1949), 206-23.
13 Ibid., p. 218. My colleague Postman
tells me that, though knowing all about the apparatus and display in
advance, he nevertheless found looking at the incongruous cards acutely
uncomfortable.
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