The Structure Of Scientific Revolutions (1962)Thomas S. Kuhn

Citations: 57,541 (one of the highest cited books in the world)

A landmark in intellectual history- Nature

Thomas S . Kuhn (1922- 1996)

• B S in Physics from Harvard University (1934)

• MS and Ph. D in 1946 and 1949, respectively

• 3 years of freedom as Harvard Junior Fellow allowed switch from physics to history and philosophy of science (1948- 51)

• Random explorations• Series of 8 public lectures delivered at

Lowell Institute in Boston

• Taught course on History of Science at Harvard University (1945- 56)

• Centre for Advanced Studies in Behavioral Science (1958- 59)

• Natural scientists vs social scientists in ability to arrive at common understanding and variety of methods adopted

Normal- scienceParadigm

Anomaly and CrisisScientific revolution

Paradigm- shiftIncommensurability

Outline (the story line)I. Introduction: A role for history

II. The route to normal science

III. The nature of normal science

IV. Normal science as puzzle- solving

V. The priority of paradigms

VI. Anomalies and the emergence of scientific discoveries

VII. Crisis and the emergence of scientific theories

VIII. The response to crisis

IX. The nature and necessity of scientific resolutions

X. Revolutions as changes of world view

XI. The invisibility of revolutions

XII. The resolution of revolutions

XIII. Progress through revolutions

I. Introduction: A role for history• If science is the constellation of facts,

theories and methods collected in current texts, then scientists are the men who, successfully or not, have striven to contribute one or another element to that particular constellation. Scientific development becomes the piecemeal process by which these items have been added, singly and in combination, to the ever growing stockpile that constitutes scientific techniques and knowledge

• History of science becomes the discipline that chronicles both these successive increments and the obstacles that have inhibited these accumulations.

• Out-of-date theories are not in principle unscientific just because they have been discarded

• Observations and experiences can and must drastically restrict the range of admissible scientific belief, else there would be no science

• Any definition of science that excludes at least the more creative members of these various schools will exclude their modern successors as well.

II. The route to Normal Science (1/2) • ‘Normal science’ means research firmly

based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundations for its further practice

• Textbooks and famous classics (e.g. Newton’s Principia and Opticks) that document such normal science shape further research because :

• Such achievements are sufficiently unprecedented

• Sufficiently open-ended leaving a lots of problems to be solved

• They are termed “Paradigms”• Men whose research is based on shared

paradigms are committed to the same rules and standards of scientific practice

• Acquisition of a paradigm and of the more esoteric type of research it permits is a sign of maturity in the development of any given scientific field

• Transformations of paradigm are scientific revolutions, and is the usual developmental pattern of mature science

• In the absence of a paradigm or some candidate for paradigm, all of the facts that could possibly pertain to the development of a given science are likely to seem equally relevant. As a result, earlier fact gathering a nearly random

• In the early stages of development of any science, different men confronting the same range of phenomenon, describe and interpret them in different ways. Such initial divergences disappear with triumph of one on pre-paradigm schools

II. The route to Normal Science (2/2) • To be accepted as a paradigm, a theory

must seem better than its competitors, but it need not, and in fact never does, explain all the facts with which it can be confronted

• When an individual scientist can take a paradigm for granted, he need no longer, in this major works, attempt to build his field anew, starting from first principles, and justifying the use of each concept introduced. This is left to textbook authors

• Once a paradigm is established, both fact collection and theory articulation become highly directed activities

• The new paradigm implies a new and more rigid definition of the field. Those unwilling or unable to accommodate their work to it must proceed in isolation or attach themselves to some other group

• Achievement of a paradigm guides a whole body of research. From this point on, researches focus on more concrete and recondite problems, and increasingly they report their results in articles addressed to fellow scientists

Two meanings of paradigm:• Entire constellation of beliefs, values,

techniques, and so on, shared by the members of a given community

• The concrete puzzle- solution which, employed as models or examples, can replace explicit rules as a basis for the resolution of the remaining puzzles of normal science

III. The nature of Normal Science• Paradigms gain their status because they

are more successful than their competitors in solving a few problems that the group of practitioner has come to recognize as acute

• This follows a lot of mopping-up work, which is carrier out by successive scientists of that normal- science, once the paradigm assumes shape

• Normal science has a drastically restricted vision, which is essential for the development of science. The paradigm forces scientists to investigate some part of the nature in a detail and depth that would otherwise be unimaginable

• Normal- science possesses a built-in mechanism that ensures the relaxation of the restrictions that bound research whenever the paradigm from which they derive ceases to function effectively

• Experimental and observations work of scientific research directed by normal or paradigm-driven science are in areas of:

• Determination of scientific facts: Attempt to increase accuracy and scope of class of facts that the paradigm has shown to be particularly revealing of the nature of things

• Matching facts with theory: Facts/ observations from nature that can be compared directly with the prediction of the paradigm

• Articulation of theory: Articulation of paradigm theory by exhausting the fact gathering activity of the normal science

• Much work is done to develop the point of contact of theory and nature (e.g. Euler, Lagrange, Laplace and Gauss worked to improve match of Newton's paradigm)

IV. Normal Science as Puzzle- solving

• Normal science is highly cumulative in enterprise

• Normal science aim little to product major novelties, conceptual or phenomenal

• Outcome that doesn’t fall in the narrow range is usually just a research failure, one which reflects not on nature but on the scientist

• Even the project whose goal is paradigm articulation doesn’t aim at unexpected novelties

• Scientist become expert puzzle- solvers• Existence of strong network of

commitments- conceptual, theoretical, instrumental, and methodological- is a principle source of metaphor that relates normal science to puzzle- solving

• Equipped with a paradigm, a scientific communities acquire criterion for choosing a problem, that can be assumed to have a solution.

• A paradigm can even isolate the community from those socially important problems that are not reducible to puzzle form

• Paradigms help set puzzles and limit the acceptable solutions

• Intrinsic value is no criteria of a puzzle, existence of a solution is

• To be classified as a puzzle, the problem must be bound by some rules and steps to solve it offered by that paradigm

V. The priorities of paradigms• Paradigms of a mature science

community can be determined with relative ease, but not rules

• Lack of a standard interpretation or of an agreed reduction to rules will not prevent a paradigm from guiding research

• Rules came later than paradigms because:

• Relative difficulty in discovering the rules• Scientists always learn new theories along

with application, not in abstraction • For as long as the problem- solution is

accepted by the community, no rule is asked for

• Substituting rules with paradigms make diversity of field understandable

• The search for rule begins when scientists disagree about whether the fundamental problems of their field have been solved

• Debates are almost non-existent during the periods of normal science, but occur regularly just before and during scientific revolutions

• Lack of rules also enable a revolution produced within one of the traditions to challenge the paradigms locally, and not extended to other paradigms (e.g. quantum mechanics, vs solid state vs Newtonian dynamics, etc)

VI. Anomaly and the emergence of scientific discoveries• Discoveries commences with awareness

of anomaly i.e. with the recognition that nature has somehow violated the paradigm- induced expectations that govern normal science

• Discovery is a process, not a single act, which comprises observation and conceptualization

• Anomalies are discouraged in normal- science as paradigm procedures and applications are as necessary to science as paradigm laws and theories, and they have the same effect. Inevitably they restrict the phenomenological field accessible for scientific investigation at any given time.

• Not all theories are paradigms. Both during paradigm periods and during crisis that leads to a large- scale change in paradigm, scientists usually develop many speculative and unarticulated theories. Only as experiments and tentative theories are together articulated to a match does the discovery emerge and the theory becomes a paradigm

• Conditions of a paradigm- shift• The previous awareness of anomaly• The gradual and simultaneous emergence

of both observations and conceptual recognition, and

• The consequent change of paradigm categories and procedures often accompanies by resistance

• Anomalies appear only against the background provided by the paradigm

VII. Crisis and emergence of scientific theories

• Normal science, a pursuit not directed to novelties and tending at first to suppress them, are in fact the necessary conditions for an anomaly/ crisis to arise

• Discoveries and inventions, both are the sources of destructive- constructive paradigm changes

• Crisis are the necessary preconditions for the emergence of novel theories

• Emergence of a new theory is generally preceded by a period of pronounced professional insecurity

• Failure of existing rules is the prelude to a search of new ones

• Breakdown of normal technical puzzle- solving activities happen with rapid occurrence of discrepancies and when discrepancy corrected in one place is likely to show up in another

• Proliferation of versions of a theory is a very usual symptom of crisis

• So long as the tools a paradigm supplies continue to prove capable of solving the problems it defines, science moves faster and penetrates most deeply through confident employment of those tools. The significance of crises is the occasion for retooling.

Examples of revolutions: Copernican astronomy, Newtonian physics and Darwinian biology

VIII. The response to crisis• The decision to reject one paradigm is

always simultaneously the decision to accept another, and the judgment leading to that decision involves the comparison of both paradigms with nature and with each other

• There is no such thing as a research in the absence of any paradigm.

• There is no such thing as a research without counter-instances

• All crisis begin with blurring of a paradigm and the consequent loosening of the rules of normal research.

• They end with:• Normal science ultimately proves to be able

to handle the crisis provoking problem• Problem persists and scientists declare the

problem unsolvable, and set for future time • Lead to emergence of a new candidate for

a paradigm and battle over its acceptance

• Crisis simultaneously loosens the stereotype the stereotype and provides the incremental data necessary for a fundamental paradigm shift

• Almost always the men who achieve fundamental inventions of a new paradigm have been either very young or very new to the field whose paradigm they change

• Symptoms of transition from normal to extraordinary science:

• Proliferation of competing articulations• Willingness to try anything • Expression of explicit discontent • Resource of philosophy• Debate over fundamentals

IX. The nature and the necessity of scientific revolutions• Scientific revolutions are those non-

cumulative developmental episodes in which an older paradigm in replaced in a whole or in part by an incompatible new one

• In both political and scientific development the sense of malfunction that can lead to a crisis is prerequisite to revolution. In either care, a paradigm shift provides a choice between incompatible modes of community life

• A new paradigm can emerge without reflecting destructively upon any part of past scientific practice. A new theory doesn’t have to conflict with any of its predecessor (e.g. quantum theories)

• Paradigms not only provide scientists map but also with some of the directions essential for map- making.

• Phenomenon about which a theory might be developed

• Phenomenon already well explained by existing paradigm

• Whose nature is indicated by existing paradigm, but whose details can be understood only through further theory articulation

• Recognized anomalies that refuse to assimilate to existing paradigm

• Scientific revolutions are displacement of the conceptual network through which scientists view the world

• New paradigm must permit predictions different from those of existing ones.

• Differences between paradigms are both necessary and irreconcilable

X. Revolutions as changes of world view

• Neither scientists nor laymen learn to see the world piecemeal or item by item. Paradigms determine large areas of experience at the same time .

• Led by a new paradigm, scientists adopt new instruments and look in new places

• It causes scientists to see the world of their research- engagement differently (like a switch in visual gestalt)

• Paradigms are not corrigible by normal science at all. Instead, normal science ultimately leads only to the recognition of anomalies and to crisis

XI. The invisibility of revolutions• Textbooks, being pedagogical vehicles

for perpetuation of normal science, obscure the scientific revolutions

• The textbook literature extends only to the outcome of most recent revolution in the field, and doesn’t talk about the paradigm shift

• This makes science seem largely cumulative

• Temptation of writing history backward is both omnipresent and perennial

XII. The resolution of revolutions (1/2)

• Any new interpretation of nature, emerges first in the mind of one individual or a few individuals.

• The resolution of revolutions happen under two circumstances:

• Intense concentration on crisis provoke problem

• Men are so young or new to the crisis- ridden field that practice has committed them less deeply than most of their contemporaries

• In so far as he is engaged in normal science, the research worker is a solver of puzzles, not a tester of paradigms

• Verification of the new paradigm happens by comparing the ability of different theories to explain the evidence at hand. One such approach is probabilistic and another is through falsification

• Popper (1959) denies the existence of any verification procedure at all. He emphasizes the importance of falsification

• Falsification happens after the anomaly is detected. It can also be called as verification, and happens wen new paradigm triumphs old one

• Causes of incommensurability of pre and post revolutionary normal- scientific traditions are:

• Disagreement about the list of problems that any candidate paradigm can solve

• Within the new paradigm, old terms, concepts and experiments fall into new relationships

• Proponents of competing paradigms practice their trade in different worlds

XII. The resolution of revolutions (2/2)

• Transitions between paradigms can’t be made a step a time, but rather it’s a switch. It may occur at once or not at all

• Scientists can’t always admit their error, even when confronted with strict proof. A generation is sometimes required to effect change.

• New paradigms succeed if it displays a quantitative precision strikingly better than the older competitor

• The new theory is said to be neater, more suitable and simpler than the old.

• When alternate ways of science are called for, then decision must be based less on past achievement than on future promise

• The man who embraces a new paradigm at an early stage must often do so in defiance of the evidence provided by the problem- solving. He must, that is, have faith that the new paradigm will succeed with the many large problems that confront it, knowing only that the old paradigm has failed with a few. A decision of that kind can only be made on faith

XIII. Progress through revolutions • Why is progress a prerequisite reserved

almost exclusively for the activities called science?

• A field is science because it makes progress

• Conditions for a scientist to accept a new paradigm

• Candidate must solve some outstanding and generally recognized problems

• Preserve a relatively large part of the concrete problem- solving ability that has accrued through its predecessors

• Scientific progress needn’t happen towards a goal, as it’s widely assumed

• The net result of a sequence of revolutionary selections, separated by periods of normal research, is the wonderfully adapted set of instruments we call modern scientific knowledge

In summary