The 9/11 Forum

SanderO wrote:The so called speed/duration/time of collapse is an interesting discussion observation. What determines when the clock of destruction actually starts?

How do we determine when it stops?

The ground is clearly shrouded in dust and not one person has mention how they determined when the collapse of the towers ended.

Was this at the cessation of noise of the structure collapsing?

Was there noise/sound at the outset? If not how does one link a visual start with no distinct sound to and audible conclusion with no visuals of it?

Sure we can guess at duration between say 12 and 20 seconds... but can this actually be established by what we have in the record? And what about the *spire* columns... don't they have to be accounted for.

So why is the speed/duration/time of destruction such an affirmative attribute of a MHOP inside job when the actual speed/duration/time is clearly not known or presented with any sort of rigor.

And what about the different between speed and acceleration. Don't you need a set of points to measure change in distance w/respect to time not a start and stop point... both of which are indeterminate to begin with. Aren't such discussions simply appeals to (junk) science which fool most people?

OneWhiteEye wrote:SanderO, very good points and interesting questions.

SanderO wrote:The so called speed/duration/time of collapse is an interesting discussion observation. What determines when the clock of destruction actually starts?

The clock of destruction is very fuzzy. The actual collapses were closer to a Rube Goldberg machine in character than a 1D axial model. It is possible to determine the time when the upper section was no longer adequately supported with reasonable precision, however. A different thing.

How do we determine when it stops?

Even more fuzzy....

In the 1950s, when Kuhn began his historical studies of science, the history of science was a young academic discipline. Even so, it was becoming clear that scientific change was not always as straightforward as the standard, traditional view would have it. Kuhn was the first and most important author to articulate a developed alternative account. Since the standard view dovetailed with the dominant, positivist-influenced philosophy of science, a non-standard view would have important consequences for the philosophy of science. Kuhn had little formal philosophical training but was nonetheless fully conscious of the significance of his innovation for philosophy, and indeed he called his work ‘history for philosophical purposes’ (Kuhn 2000, 276).

According to Kuhn the development of a science is not uniform but has alternating ‘normal’ and ‘revolutionary’ (or ‘extraordinary’) phases. The revolutionary phases are not merely periods of accelerated progress, but differ qualitatively from normal science. Normal science does resemble the standard cumulative picture of scientific progress, on the surface at least. Kuhn describes normal science as ‘puzzle-solving’ (1962/1970a, 35–42). While this term suggests that normal science is not dramatic, its main purpose is to convey the idea that like someone doing a crossword puzzle or a chess problem or a jigsaw, the puzzle-solver expects to have a reasonable chance of solving the puzzle, that his doing so will depend mainly on his own ability, and that the puzzle itself and its methods of solution will have a high degree of familiarity. A puzzle-solver is not entering completely uncharted territory. Because its puzzles and their solutions are familiar and relatively straightforward, normal science can expect to accumulate a growing stock of puzzle-solutions. Revolutionary science, however, is not cumulative in that, according to Kuhn, scientific revolutions involve a revision to existing scientific belief or practice (1962/1970a, 92).

If, as in the standard picture, scientific revolutions are like normal science but better, then revolutionary science will at all times be regarded as something positive, to be sought, promoted, and welcomed. Revolutions are to be sought on Popper's view also, but not because they add to positive knowledge of the truth of theories but because they add to the negative knowledge that the relevant theories are false. Kuhn rejected both the traditional and Popperian views in this regard. He claims that normal science can succeed in making progress only if there is a strong commitment by the relevant scientific community to their shared theoretical beliefs, values, instruments and techniques, and even metaphysics. This constellation of shared commitments Kuhn at one point calls a ‘disciplinary matrix’ (1970a, 182) although elsewhere he often uses the term ‘paradigm’. Because commitment to the disciplinary matrix is a pre-requisite for successful normal science, an inculcation of that commitment is a key element in scientific training and in the formation of the mind-set of a successful scientist. This tension between the desire for innovation and the necessary conservativeness of most scientists was the subject of one of Kuhn's first essays in the theory of science, “The Essential Tension” (1959). The unusual emphasis on a conservative attitude distinguishes Kuhn not only from the heroic element of the standard picture but also from Popper and his depiction of the scientist forever attempting to refute her most important theories.

This conservative resistance to the attempted refutation of key theories means that revolutions are not sought except under extreme circumstances. Popper's philosophy requires that a single reproducible, anomalous phenomenon be enough to result in the rejection of a theory (Popper 1959, 86–7). Kuhn's view is that during normal science scientists neither test nor seek to confirm the guiding theories of their disciplinary matrix. Nor do they regard anomalous results as falsifying those theories. (It is only speculative puzzle-solutions that can be falsified in a Popperian fashion during normal science (1970b, 19).) Rather, anomalies are ignored or explained away if at all possible. It is only the accumulation of particularly troublesome anomalies that poses a serious problem for the existing disciplinary matrix. A particularly troublesome anomaly is one that undermines the practice of normal science. For example, an anomaly might reveal inadequacies in some commonly used piece of equipment, perhaps by casting doubt on the underlying theory. If much of normal science relies upon this piece of equipment, normal science will find it difficult to continue with confidence until this anomaly is addressed. A widespread failure in such confidence Kuhn calls a ‘crisis’ (1962/1970a, 66–76).

The most interesting response to crisis will be the search for a revised disciplinary matrix, a revision that will allow for the elimination of at least the most pressing anomalies and optimally the solution of many outstanding, unsolved puzzles. Such a revision will be a scientific revolution. According to Popper the revolutionary overthrow of a theory is one that is logically required by an anomaly. According to Kuhn however, there are no rules for deciding the significance of a puzzle and for weighing puzzles and their solutions against one another. The decision to opt for a revision of a disciplinary matrix is not one that is rationally compelled; nor is the particular choice of revision rationally compelled. For this reason the revolutionary phase is particularly open to competition among differing ideas and rational disagreement about their relative merits. Kuhn does briefly mention that extra-scientific factors might help decide the outcome of a scientific revolution—the nationalities and personalities of leading protagonists, for example (1962/1970a, 152–3).

Kuhn states that science does progress, even through revolutions (1962/1970a, 160ff.). The phenomenon of Kuhn-loss does, in Kuhn's view, rule out the traditional cumulative picture of progress. The revolutionary search for a replacement paradigm is driven by the failure of the existing paradigm to solve certain important anomalies. Any replacement paradigm had better solve the majority of those puzzles, or it will not be worth adopting in place of the existing paradigm. At the same time, even if there is some Kuhn-loss, a worthy replacement must also retain much of the problem-solving power of its predecessor (1962/1970a, 169). (Kuhn does clarify the point by asserting that the newer theory must retain pretty well all its predecessor's power to solve quantitative problems. It may however lose some qualitative, explanatory power (1970b, 20).) Hence we can say that revolutions do bring with them an overall increase in puzzle-solving power, the number and significance of the puzzles and anomalies solved by the revised paradigm exceeding the number and significance of the puzzles-solutions that are no longer available as a result of Kuhn-loss.

3. The Concept of a Paradigm

A mature science, according to Kuhn, experiences alternating phases of normal science and revolutions. In normal science the key theories, instruments, values and metaphysical assumptions that comprise the disciplinary matrix are kept fixed, permitting the cumulative generation of puzzle-solutions, whereas in a scientific revolution the disciplinary matrix undergoes revision, in order to permit the solution of the more serious anomalous puzzles that disturbed the preceding period of normal science.

A particularly important part of Kuhn's thesis in The Structure of Scientific Revolutions focuses upon one specific component of the disciplinary matrix. This is the consensus on exemplary instances of scientific research. These exemplars of good science are what Kuhn refers to when he uses the term ‘paradigm’ in a narrower sense. He cites Aristotle's analysis of motion, Ptolemy's computations of plantery positions, Lavoisier's application of the balance, and Maxwell's mathematization of the electromagnetic field as paradigms (1962/1970a, 23). Exemplary instances of science are typically to be found in books and papers, and so Kuhn often also describes great texts as paradigms—Ptolemy's Almagest, Lavoisier's Traité élémentaire de chimie, and Newton's Principia Mathematica and Opticks (1962/1970a, 12). Such texts contain not only the key theories and laws, but also—and this is what makes them paradigms—the applications of those theories in the solution of important problems, along with the new experimental or mathematical techniques (such as the chemical balance in Traité élémentaire de chimie and the calculus in Principia Mathematica) employed in those applications.

In the postscript to the second edition of The Structure of Scientific Revolutions Kuhn says of paradigms in this sense that they are “the most novel and least understood aspect of this book” (1962/1970a, 187). The claim that the consensus of a disciplinary matrix is primarily agreement on paradigms-as-exemplars is intended to explain the nature of normal science and the process of crisis, revolution, and renewal of normal science. It also explains the birth of a mature science. Kuhn describes an immature science, in what he sometimes calls its ‘pre-paradigm’ period, as lacking consensus. Competing schools of thought possess differing procedures, theories, even metaphysical presuppositions. Consequently there is little opportunity for collective progress. Even localized progress by a particular school is made difficult, since much intellectual energy is put into arguing over the fundamentals with other schools instead of developing a research tradition. However, progress is not impossible, and one school may make a breakthrough whereby the shared problems of the competing schools are solved in a particularly impressive fashion. This success draws away adherents from the other schools, and a widespread consensus is formed around the new puzzle-solutions.

This widespread consensus now permits agreement on fundamentals. For a problem-solution will embody particular theories, procedures and instrumentation, scientific language, metaphysics, and so forth. Consensus on the puzzle-solution will thus bring consensus on these other aspects of a disciplinary matrix also. The successful puzzle-solution, now a paradigm puzzle-solution, will not solve all problems. Indeed, it will probably raise new puzzles. For example, the theories it employs may involve a constant whose value is not known with precision; the paradigm puzzle-solution may employ approximations that could be improved; it may suggest other puzzles of the same kind; it may suggest new areas for investigation. Generating new puzzles is one thing that the paradigm puzzle-solution does; helping solve them is another. In the most favourable scenario, the new puzzles raised by the paradigm puzzle-solution can be addressed and answered using precisely the techniques that the paradigm puzzle-solution employs. And since the paradigm puzzle-solution is accepted as a great achievement, these very similar puzzle-solutions will be accepted as successful solutions also. This is why Kuhn uses the terms ‘exemplar’ and ‘paradigm’. For the novel puzzle-solution which crystallizes consensus is regarded and used as a model of exemplary science. In the research tradition it inaugurates, a paradigm-as-exemplar fulfils three functions: (i) it suggests new puzzles; (ii) it suggests approaches to solving those puzzles; (iii) it is the standard by which the quality of a proposed puzzle-solution can be measured (1962/1970a, 38–9). In each case it is similarity to the exemplar that is the scientists’ guide.

4. Incommensurability and World-Change

The standard empiricist conception of theory evaluation regards our judgment of the epistemic quality of a theory to be a matter of applying rules of method to the theory and the evidence. Kuhn's contrasting view is that we judge the quality of a theory (and its treatment of the evidence) by comparing it to a paradigmatic theory. The standards of assessment therefore are not permanent, theory-independent rules. They are not rules, because they involve perceived relations of similarity (of puzzle-solution to a paradigm). They are not theory-independent, since they involve comparison to a (paradigm) theory. They are not permanent, since the paradigm may change in a scientific revolution.

4.2 Perception, Observational Incommensurability, and World-Change

An important focus of Kuhn's interest in The Structure of Scientific Revolutions was on the nature of perception and how it may be that what a scientist observes can change as a result of scientific revolution. He developed what has become known as the thesis of the theory-dependence of observation, building on the work of N. R. Hanson (1958) while also referring to psychological studies carried out by his Harvard colleagues, Leo Postman and Jerome Bruner (Bruner and Postman 1949). The standard positivist view was that observation provides the neutral arbiter between competing theories. The thesis that Kuhn and Hanson promoted denied this, holding that the nature of observation may be influenced by prior beliefs and experiences. Consequently it cannot be expected that two scientists when observing the same scene will make the same theory-neutral observations. Kuhn asserts that Galileo and an Aristotelian when both looking at a pendulum will see different things (see quoted passage below).

The theory-dependence of observation, by rejecting the role of observation as a theory-neutral arbiter among theories, provides another source of incommensurability. Methodological incommensurability (§4.1 above) denies that there are universal methods for making inferences from the data. The theory-dependence of observation means that even if there were agreed methods of inference and interpretation, incommensurability could still arise since scientists might disagree on the nature of the observational data themselves.

Kuhn expresses or builds on the idea that participants in different disciplinary matrices will see the world differently by claiming that their worlds are different:

In a sense I am unable to explicate further, the proponents of competing paradigms practice their trades in different worlds. One contains constrained bodies that fall slowly, the other pendulums that repeat their motions again and again. In one, solutions are compounds, in the other mixtures. One is embedded in a flat, the other in a curved, matrix of space. Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction (1962/1970a, 150).

Remarks such as these gave some commentators the impression that Kuhn was a strong kind of constructivist, holding that the way the world literally is depends on which scientific theory is currently accepted. Kuhn, however, denied any constructivist import to his remarks on world-change. (The closest Kuhn came to constructivism was to acknowledge a parallel with Kantian idealism, which is discussed below in Section 6.4.)

Kuhn likened the change in the phenomenal world to the Gestalt-switch that occurs when one sees the duck-rabbit diagram first as (representing) a duck then as (representing) a rabbit, although he himself acknowledged that he was not sure whether the Gestalt case was just an analogy or whether it illustrated some more general truth about the way the mind works that encompasses the scientific case too.

Chapter I - Introduction: A Role for History.

Kuhn begins by formulating some assumptions that lay the foundation for subsequent discussion and by briefly outlining the key contentions of the book.

A) A scientific community cannot practice its trade without some set of received beliefs (p. 4).
... 1) These beliefs form the foundation of the "educational initiation that prepares and licenses the student for professional practice" (5).
... 2) The nature of the "rigorous and rigid" preparation helps ensure that the received beliefs exert a "deep hold" on the student's mind.
B) Normal science "is predicated on the assumption that the scientific community knows what the world is like" (5)—scientists take great pains to defend that assumption.
C) To this end, "normal science often suppresses fundamental novelties because they are necessarily subversive of its basic commitments" (5).
D) Research is "a strenuous and devoted attempt to force nature into the conceptual boxes supplied by professional education" (5).
E) A shift in professional commitments to shared assumptions takes place when an anomaly "subverts the existing tradition of scientific practice" (6). These shifts are what Kuhn describes as scientific revolutions—"the tradition-shattering complements to the tradition-bound activity of normal science" (6).
... 1) New assumptions (paradigms/theories) require the reconstruction of prior assumptions and the reevaluation of prior facts. This is difficult and time consuming. It is also strongly resisted by the established community.
... 2) When a shift takes place, "a scientist's world is qualitatively transformed [and] quantitatively enriched by fundamental novelties of either fact or theory" (7).

Chapter III - The Nature of Normal Science.

If a paradigm consists of basic and incontrovertible assumptions about the nature of the discipline, what questions are left to ask?

When they first appear, paradigms are limited in scope and in precision.
"Paradigms gain their status because they are more successful than their competitors in solving a few problems that the group of practitioners has come to recognize as acute" (23).
But more successful does not mean completely successful with a single problem or notably successful with any large number (23).
Initially, a paradigm offers the promise of success.
Normal science consists in the actualization of that promise. This is achieved by
extending the knowledge of those facts that the paradigm displays as particularly revealing,
increasing the extent of the match between those facts and the paradigm's predictions,
and further articulation of the paradigm itself.
In other words, there is a good deal of mopping-up to be done.
Mop-up operations are what engage most scientists throughout their careers.
Mopping-up is what normal science is all about!
This paradigm-based research (25) is "an attempt to force nature into the preformed and relatively inflexible box that the paradigm supplies" (24).
no effort made to call forth new sorts of phenomena.
no effort to discover anomalies.
when anomalies pop up, they are usually discarded or ignored.
anomalies usually not even noticed (tunnel vision/one track mind).
no effort to invent new theory (and no tolerance for those who try).
"Normal-scientific research is directed to the articulation of those phenomena and theories that the paradigm already supplies" (24).
"Perhaps these are defects . . . "
". . . but those restrictions, born from confidence in a paradigm, turn out to be essential to the development of science. By focusing attention on a small range of relatively esoteric problems, the paradigm forces scientists to investigate some part of nature in a detail and depth that would otherwise be unimaginable" (24).
. . . and, when the paradigm ceases to function properly, scientists begin to behave differently and the nature of their research problems changes.
Mopping-up can prove fascinating work (24). [You do it. We all do it. And we love to do it. In fact, we'd do it for free.]
The principal problems of normal science.
Determination of significant fact.
A paradigm guides and informs the fact-gathering (experiments and observations described in journals) decisions of researchers?
Researchers focus on, and attempt to increase the accuracy and scope of, facts (constructs/concepts) that the paradigm has shown to be particularly revealing of the nature of things (25).
Matching of facts with theory.
Researchers focus on facts that can be compared directly with predictions from the paradigmatic theory (26)
Great effort and ingenuity are required to bring theory and nature into closer and closer agreement.
A paradigm sets the problems to be solved (27).
Articulation of theory.
Researchers undertake empirical work to articulate the paradigm theory itself (27)—resolve residual ambiguities, refine, permit solution of problems to which the theory had previously only drawn attention. This articulation includes
determination of universal constants.
development of quantitative laws.
selection of ways to apply the paradigm to a related area of interest.
This is, in part, a problem of application (but only in part).
Paradigms must undergo reformulation so that their tenets closely correspond to the natural object of their inquiry (clarification by reformulation).
"The problems of paradigm articulation are simultaneously theoretical and experimental" (33).
Such work should produce new information and a more precise paradigm.
This is the primary work of many sciences.
To desert the paradigm is to cease practicing the science it defines (34).

Chapter IV - Normal Science as Puzzle-solving.
Doing research is essentially like solving a puzzle. Puzzles have rules. Puzzles generally have predetermined solutions.

A striking feature of doing research is that the aim is to discover what is known in advance.
This in spite of the fact that the range of anticipated results is small compared to the possible results.
When the outcome of a research project does not fall into this anticipated result range, it is generally considered a failure, i.e., when "significance" is not obtained.
Studies that fail to find the expected are usually not published.
The proliferation of studies that find the expected helps ensure that the paradigm/theory will flourish.
Even a project that aims at paradigm articulation does not aim at unexpected novelty.
"One of the things a scientific community acquires with a paradigm is a criterion for choosing problems that, while the paradigm is taken for granted, can be assumed to have solutions" (37).
The intrinsic value of a research question is not a criterion for selecting it.
The assurance that the question has an answer is the criterion (37).
"The man who is striving to solve a problem defined by existing knowledge and technique is not just looking around. He knows what he wants to achieve, and he designs his instruments and directs his thoughts accordingly" (96).
So why do research?
Results add to the scope and precision with which a paradigm/theory can be applied.
The way to obtain the results usually remains very much in doubt—this is the challenge of the puzzle.
Solving the puzzle can be fun, and expert puzzle-solvers make a very nice living.

Chapter VI - Anomaly and the Emergence of Scientific Discoveries.

If normal science is so rigid and if scientific communities are so close-knit, how can a paradigm change take place? This chapter traces paradigm changes that result from discovery brought about by encounters with anomaly.

Normal science does not aim at novelties of fact or theory and, when successful, finds none.
Nonetheless, new and unsuspected phenomena are repeatedly uncovered by scientific research, and radical new theories have again and again been invented by scientists (52).
Fundamental novelties of fact and theory bring about paradigm change.
So how does paradigm change come about?
Discovery—novelty of fact.
Discovery begins with the awareness of anomaly.
The recognition that nature has violated the paradigm-induced expectations that govern normal science.
A phenomenon for which a paradigm has not readied the investigator.
Perceiving an anomaly is essential for perceiving novelty (although the first does not always lead to the second, i.e., anomalies can be ignored, denied, or unacknowledged).
The area of the anomaly is then explored.
The paradigm change is complete when the paradigm/theory has been adjusted so that the anomalous become the expected.
The result is that the scientist is able "to see nature in a different way" (53).
But careful: Discovery involves an extended process of conceptual assimilation, but assimilating new information does not always lead to paradigm change.
Invention—novelty of theory.
Not all theories are paradigm theories.
Unanticipated outcomes derived from theoretical studies can lead to the perception of an anomaly and the awareness of novelty.
How paradigms change as a result of invention is discussed in greater detail in the following chapter.
The process of paradigm change is closely tied to the nature of perceptual (conceptual) change in an individual—Novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation (64).
Although normal science is a pursuit not directed to novelties and tending at first to suppress them, it is nonetheless very effective in causing them to arise. Why?
An initial paradigm accounts quite successfully for most of the observations and experiments readily accessible to that science's practitioners.
Research results in
the construction of elaborate equipment,
development of an esoteric and shared vocabulary,
refinement of concepts that increasingly lessens their resemblance to their usual common-sense prototypes.
This professionalization leads to
immense restriction of the scientist's vision, rigid science, and resistance to paradigm change.
a detail of information and precision of the observation-theory match that can be achieved in no other way.
New and refined methods and instruments result in greater precision and understanding of the paradigm/theory.
Only when researchers know with precision what to expect from an experiment can they recognize that something has gone wrong.
Consequently, anomaly appears only against the background provided by the paradigm (65).
The more precise and far-reaching the paradigm, the more sensitive it is to detecting an anomaly and inducing change.
By resisting change, a paradigm guarantees that anomalies that lead to paradigm change will penetrate existing knowledge to the core.

Chapter VII - Crisis and the Emergence of Scientific Theories.

This chapter traces paradigm changes that result from the invention of new theories brought about by the failure of existing theory to solve the problems defined by that theory. This failure is acknowledged as a crisis by the scientific community.

As is the case with discovery, a change in an existing theory that results in the invention of a new theory is also brought about by the awareness of anomaly.
The emergence of a new theory is generated by the persistent failure of the puzzles of normal science to be solved as they should. Failure of existing rules is the prelude to a search for new ones (68). These failures can be brought about by
observed discrepancies between theory and fact—this is the "core of the crisis" (69).
changes in social/cultural climates (knowledge/beliefs are socially constructed?).
There are strong historical precedents for this: Copernicus, Freud, behaviorism? constructivism?
Science is often "ridden by dogma" (75)—what may be the effect on science (or art) by an atmosphere of political correctness?
scholarly criticism of existing theory.
Such failures are generally long recognized, which is why crises are seldom surprising.
Neither problems nor puzzles yield often to the first attack (75).
Recall that paradigm and theory resist change and are extremely resilient.
Philosophers of science have repeatedly demonstrated that more than one theoretical construction can always be placed upon a given collection of data (76).
In early stages of a paradigm, such theoretical alternatives are easily invented.
Once a paradigm is entrenched (and the tools of the paradigm prove useful to solve the problems the paradigm defines), theoretical alternatives are strongly resisted.
As in manufacture so in science—retooling is an extravagance to be reserved for the occasion that demands it (76).
Crises provide the opportunity to retool.

Chapter VIII - The Response to Crisis.

The awareness and acknowledgment that a crisis exists loosens theoretical stereotypes and provides the incremental data necessary for a fundamental paradigm shift. In this critical chapter, Kuhn discusses how scientists respond to the anomaly in fit between theory and nature so that a transition to crisis and to extraordinary science begins, and he foreshadows how the process of paradigm change takes place.

Normal science does and must continually strive to bring theory and fact into closer agreement.
The recognition and acknowledgment of anomalies result in crises that are a necessary precondition for the emergence of novel theories and for paradigm change.
Crisis is the essential tension implicit in scientific research (79).
There is no such thing as research without counterinstances, i.e., anomaly.
These counterinstances create tension and crisis.
Crisis is always implicit in research because every problem that normal science sees as a puzzle can be seen, from another viewpoint, as a counterinstance and thus as a source of crisis (79).
In responding to these crises, scientists generally do not renounce the paradigm that has led them into crisis.
They may lose faith and consider alternatives, but
they generally do not treat anomalies as counterinstances of expected outcomes.
They devise numerous articulations and ad hoc modifications of their theory in order to eliminate any apparent conflict.
Some, unable to tolerate the crisis (and thus unable to live in a world out of joint), leave the profession.
As a rule, persistent and recognized anomaly does not induce crisis (81).
Failure to achieve the expected solution to a puzzle discredits only the scientist and not the theory ("it is a poor carpenter who blames his tools").
Science is taught to ensure confirmation-theory.
Science students accept theories on the authority of teacher and text—what alternative do they have, or what competence?
To evoke a crisis, an anomaly must usually be more than just an anomaly.
After all, there are always anomalies (counterinstances).
Scientists who paused and examined every anomaly would not get much accomplished.
An anomaly can call into question fundamental generalizations of the paradigm.
An anomaly without apparent fundamental import may also evoke crisis if the applications that it inhibits have a particular practical importance.
An anomaly must come to be seen as more than just another puzzle of normal science.
In the face of efforts outlined in C above, the anomaly must continue to resist.
All crises begin with the blurring of a paradigm and the consequent loosening of the rules for normal research. As this process develops,
the anomaly comes to be more generally recognized as such.
more attention is devoted to it by more of the field's eminent authorities.
the field begins to look quite different.
scientists express explicit discontent.
competing articulations of the paradigm proliferate.
scholars view a resolution as the subject matter of their discipline. To this end, they
first isolate the anomaly more precisely and give it structure.
push the rules of normal science harder than ever to see, in the area of difficulty, just where and how far they can be made to work.
seek for ways of magnifying the breakdown.
generate speculative theories.
If successful, one theory may disclose the road to a new paradigm.
If unsuccessful, the theories can be surrendered with relative ease.
may turn to philosophical analysis and debate over fundamentals as a device for unlocking the riddles of their field.
crisis often proliferates new discoveries.
All crises close in one of three ways.
Normal science proves able to handle the crisis-provoking problem and all returns to "normal."
The problem resists and is labeled, but it is perceived as resulting from the field's failure to possess the necessary tools with which to solve it, and so scientists set it aside for a future generation with more developed tools.
A new candidate for paradigm emerges, and a battle over its acceptance ensues (84)—these are the paradigm wars.
Once it has achieved the status of paradigm, a paradigm is declared invalid only if an alternate candidate is available to take its place (77).
Because there is no such thing as research in the absence of a paradigm, to reject one paradigm without simultaneously substituting another is to reject science itself.
To declare a paradigm invalid will require more than the falsification of the paradigm by direct comparison with nature.
The judgment leading to this decision involves the comparison of the existing paradigm with nature and with the alternate candidate.
Transition from a paradigm in crisis to a new one from which a new tradition of normal science can emerge is not a cumulative process. It is a reconstruction of the field from new fundamentals (85). This reconstruction
changes some of the field's foundational theoretical generalizations.
changes methods and applications.
alters the rules.
How do new paradigms finally emerge?
Some emerge all at once, sometimes in the middle of the night, in the mind of a man deeply immersed in crisis.
Those who achieve fundamental inventions of a new paradigm have generally been either very young or very new to the field whose paradigm they changed.
Much of this process is inscrutable and may be permanently so.
When a transition from former to alternate paradigm is complete, the profession changes its view of the field, its methods, and its goals.
This reorientation has been described as "handling the same bundle of data as before, but placing them in a new system of relations with one another by giving them a different framework" or "picking up the other end of the stick" (85).
Some describe the reorientation as a gestalt shift.
Kuhn argues that the gestalt metaphor is misleading: "Scientists do not see something as something else; instead, they simply see it" (85).
The emergence of a new paradigm/theory breaks with one tradition of scientific practice that is perceived to have gone badly astray and introduces a new one conducted under different rules and within a different universe of discourse.
The transition to a new paradigm is scientific revolution—and this is the transition from normal to extraordinary research.

Mop-ping-up operations are what
engage most scientists throughout their careers. They constitute what I
am here calling normal science. Closely examined, whether historically
or in the contemporary laboratory, that enterprise seems an attempt to
force nature into the preformed and relatively inflexible box that the
paradigm supplies. No part of the aim of normal science is to call forth
new sorts of phenomena; indeed those that will not fit the box are often
not seen at all. Nor do scientists normally aim to invent new theories,
and they are often intolerant of those invented by others.1 Instead,
normal-scientific research is directed to the articulation of those
phenomena and theories that the paradigm already supplies.

We have already seen, however, that one of the things a scientific
community acquires with a paradigm is a criterion for choosing
problems that, while the paradigm is taken for granted, can be assumed
to have solutions. To a great extent these are the only problems that the
community will admit as scientific or encourage its members to
undertake. Other problems, including many that had previously been
standard, are rejected as metaphysical, as the concern of another
discipline, or sometimes as just too problematic to be worth the time. A
paradigm can, for that matter, even insulate the community from those
socially important problems that are not reducible to the puzzle form,
because they cannot be stated in terms of the conceptual and
instrumental tools the paradigm supplies.

...

One of the reasons why normal science seems to
progress so rapidly is that its practitioners concentrate on problems that
only their own lack of ingenuity should keep them from solving.

Why should a change of
paradigm be called a revolution? In the face of the vast and essential
differences between political and scientific development, what
parallelism can justify the metaphor that finds revolutions in both?

One aspect of the parallelism must already be apparent. Political
revolutions are inaugurated by a growing sense, often restricted to a
segment of the political community, that existing institutions have
ceased adequately to meet the problems posed by an environment that
they have in part created. In much the same way, scientific revolutions
are inaugurated by a growing sense, again often restricted to a narrow
subdivision of the scientific community, that an existing paradigm has
ceased to function adequately in the exploration of an aspect of nature
to which that paradigm itself had previously led the way. In both
political and scientific development the sense of malfunction that can
lead to crisis is prerequisite to revolution.

Like the choice between competing political
institutions, that between competing paradigms proves to be a choice
between incompatible modes of community life. Because it has that
character, the choice is not and cannot be determined merely by the
evaluative procedures characteristic of normal science, for these depend
in part upon a particular paradigm, and that paradigm is at issue. When
paradigms enter, as they must, into a debate about paradigm choice,
their role is necessarily circular. Each group uses its own paradigm to
argue in that paradigm’s defense.

A
second class of phenomena consists of those whose nature is indicated
by existing paradigms but whose details can be understood only through
further theory articulation. These are the phenomena to which
scientists direct their research much of the time, but that research aims
at the articulation of existing paradigms rather than at the invention of
new ones. Only when these attempts at articulation fail do scientists
encounter the third type of phenomena, the recognized anomalies
whose characteristic feature is their stubborn refusal to be assimilated to
existing paradigms. This type alone gives rise to new theories. Paradigms
provide all phenomena except anomalies with a theory-determined
place in the scientist’s field of vision.

Literally as well as
metaphorically, the man accustomed to inverting lenses has undergone
a revolutionary transformation of vision.
The subjects of the anomalous playing-card experiment discussed in
Section VI experienced a quite similar transformation. Until taught by
prolonged exposure that the universe contained
anomalous cards, they saw only the types of cards for which previous
experience had equipped them. Yet once experience had provided the
requisite additional categories, they were able to see all anomalous cards
on the first inspection long enough to permit any identification at all.
Still other experiments demonstrate that the perceived size, color, and
so on, of experimentally displayed objects also varies with the subject’s
previous training and experience.2 Surveying the rich experimental
literature from which these examples are drawn makes one suspect that
something like a paradigm is prerequisite to perception itself. What a
man sees depends both upon what he looks at and also upon what his
previous visual-conceptual experience has taught him to see. In the
absence of such training there can only be, in William James’s phrase, “a
bloomin’ buzzin’ confusion.

But is sensory experience fixed and neutral? Are theories simply man-
made interpretations of given data? The epistemological viewpoint that
has most often guided Western philosophy for three centuries dictates
an immediate and unequivocal, Yes! In the absence of a developed
alternative, I find it impossible to relinquish entirely that viewpoint. Yet
it no longer functions effectively, and the attempts to make it do so
through the introduction of a neutral language of observations now
seem to me hopeless.

The operations and measurements that a scientist undertakes in the
laboratory are not “the given” of experience but rather “the collected
with difficulty.” They are not what the scientist sees—at least not before
his research is well advanced and his attention focused. Rather, they are
concrete indices to the content of more elementary perceptions, and as
such they are selected for the close scrutiny of normal research only
because they promise opportunity for the fruitful elaboration of an
accepted paradigm. Far more clearly than the immediate experience
from which they in part derive, operations and measurements are
paradigm-determined.

with the same retinal impressions can see different things; the inverting
lenses show that two men with different retinal impressions can see the
same thing. Psychology supplies a great deal of other evidence to the
same effect, and the doubts that derive from it are readily reinforced by
the history of attempts to exhibit an actual language of observation. No
current attempt to achieve that end has yet come close to a generally
applicable language of pure percepts. And those attempts that come
closest share one characteristic that strongly reinforces several of this
essay’s main theses. From the start they presuppose a paradigm, taken
either from a current scientific theory or from some fraction of everyday
discourse, and they then try to eliminate from it all non-logical and non-
perceptual terms. In a few realms of discourse this effort has been
carried very far and with fascinating results. There can be no question
that efforts of this sort are worth pursuing. But their result is a language
that—like those employed in the sciences—embodies a host of
expectations about nature and fails to function the moment these
expectations are violated.

I suggest that there are excellent reasons why revolutions
have proved to be so nearly invisible. Both scientists and laymen take
much of their image of creative scientific activity from an authoritative
source that systematically disguises—partly for important functional
reasons—the existence and significance of scientific revolutions. Only
when the nature of that authority is recognized and analyzed can one
hope to make historical example fully effective.

For the moment let us simply take it for granted that, to an extent
unprecedented in other fields, both the layman’s and the practitioner’s
knowledge of science is based on textbooks and a few other types of
literature derived from them. Textbooks, however, being pedagogic
vehicles for the perpetuation of normal science, have to be rewritten in
whole or in part whenever the language, problem-structure, or
standards of normal science change. In short, they have to be rewritten
in the aftermath of each scientific revolution, and, once rewritten, they
inevitably disguise not only the role but the very existence of the
revolutions that produced them. Unless he has personally experienced a
revolution in his own lifetime, the historical sense either of the working
scientist or of the lay reader of textbook literature extends only to the
outcome of the most recent revolutions in the field.

Textbooks thus begin by truncating the scientist’s sense of his
discipline’s history and then proceed to supply a substitute for what
they have eliminated. Characteristically, textbooks of science contain
just a bit of history, either in an introductory
chapter or, more often, in scattered references to the great heroes of an
earlier age. From such references both students and professionals come
to feel like participants in a long-standing historical tradition. Yet the
textbook-derived tradition in which scientists come to sense their
participation is one that, in fact, never existed. For reasons that are both
obvious and highly functional, science textbooks (and too many of the
older histories of science) refer only to that part of the work of past
scientists that can easily be viewed as contributions to the statement and
solution of the texts’ paradigm problems. Partly by selection and partly
by distortion, the scientists of earlier ages are implicitly represented as
having worked upon the same set of fixed problems and in accordance
with the same set of fixed canons that the most recent revolution in
scientific theory and method has made seem scientific. No wonder that
textbooks ‘ and the historical tradition they imply have to be rewritten
after each scientific revolution. And no wonder that, as they are
rewritten, science once again comes to seem largely cumulative.
Scientists are not, of course, the only group that tends to see its
discipline’s past developing linearly toward its present vantage. The
temptation to write history backward is both omnipresent and
perennial. But scientists are more affected by the temptation to rewrite
history, partly because the results of scientific research show no obvious
dependence upon the historical context of the inquiry, and partly
because, except during crisis and revolution, the scientist’s
contemporary position seems so secure. More historical detail, whether
of science’s present or of its past, or more responsibility to the historical
details that are presented, could only give artificial status to human
idiosyncrasy, error, and confusion.

The depreciation of historical fact is deeply, and probably functionally,
ingrained in the ideology of the scientific profession, the same
profession that places the highest of all values upon factual details of
other sorts. Whitehead caught the unhistorical spirit of the scientific
community when he wrote, “A science that hesitates to forget its
founders is lost.” Yet he was not quite right, for the sciences, like other
professional enterprises, do need their
heroes and do preserve their names. Fortunately, instead of forgetting
these heroes, scientists have been able to forget or revise their works.

The result is a persistent tendency to make the history of science look
linear or cumulative, a tendency that even affects scientists looking back
at their own research.

By disguising such
changes, the textbook tendency to make the development of science
linear hides a process that lies at the heart of the most significant
episodes of scientific development.
The preceding examples display, each within the context of a single
revolution, the beginnings of a reconstruction of history that is regularly
completed by postrevolutionary science texts. But in that completion
more is involved than a multiplication of the historical misconstructions
illustrated above. Those misconstructions render revolutions invisible;
the arrangement of the still visible material in science texts implies a
process that, if it existed, would deny revolutions a function. Because
they aim quickly to acquaint the student with what the contemporary
scientific community thinks it knows, textbooks treat the various
experiments, concepts, laws, and theories of the current normal science
as separately and as nearly seriatim as possible. As pedagogy this
technique of presentation is unexceptionable. But when combined with
the generally unhistorical air of science writing and with the occasional
systematic misconstructions discussed above, one strong impression is
overwhelmingly likely to follow: science has reached its present state by
a series of individual discoveries and inventions that, when gathered
together, constitute the modern body of technical knowledge. From the
beginning of the scientific enterprise, a textbook presentation implies,
scientists have striven for the particular objectives that are embodied in
today’s paradigms. One by one, in a process often compared to the
addition of bricks to a building, scientists have added another fact,
concept, law, or theory to the body of information supplied in the
contemporary science text.

But that is not the way a science develops.