The Structure of Scientific Revolutions

Summary

Thomas Kuhn's essay argues that the sciences do not grow by steady accumulation of facts but pass through long periods of settled work broken by revolutions in which the framework of a field is replaced. It was first published in 1962 by the University of Chicago Press as a monograph in the International Encyclopedia of Unified Science, and a second edition of 1970 added a Postscript answering critics. The book is under copyright, so this library describes it in its own words and gives only two short quotations. Kuhn opens by proposing that the history of science, taken seriously, would change the picture of science found in textbooks. A mature science begins when a community accepts a paradigm: a shared achievement, such as Newton's Principia or Lavoisier's chemistry, that defines legitimate problems and methods. Before that, schools compete, as in early studies of electricity. Normal science then follows, which Kuhn compares to puzzle-solving: scientists extend and refine the paradigm, determine constants and fit nature more closely to it, without seeking fundamental novelty. Anomalies arise, results that resist the paradigm, as in the discovery of oxygen by Priestley and Lavoisier, of X-rays by Roentgen, and of the Leyden jar. Kuhn draws on a psychological experiment by Bruner and Postman with anomalous playing cards to show how expectation shapes perception. When anomalies accumulate, a field enters crisis, as astronomy did before Copernicus, chemistry before Lavoisier, and physics before relativity. Scientists do not abandon a paradigm simply because it faces counterinstances; they abandon it only when another is available. A revolution follows, which Kuhn compares to a political revolution and to a gestalt switch: after it, scientists see the world differently, and the old and new paradigms are in important ways incommensurable, using terms like mass or element in different senses. The choice between paradigms cannot be settled by logic and experiment alone, and Kuhn likens the change of allegiance to a conversion. Textbooks then rewrite history so that revolutions become invisible and the past looks like a line of progress toward the present. In the last section Kuhn asks in what sense science progresses, and answers that it moves away from earlier states rather than toward a fixed goal, much as Darwin's evolution has no goal. The 1969 Postscript distinguishes two senses of paradigm, the disciplinary matrix of a community and the shared exemplars by which students learn, and rejects the charge that his account makes theory choice irrational.

Plot or Argument

• Section I: a role for history

  Kuhn argues that the image of science as accumulation, drawn from textbooks, does not fit the historical record, where discoveries are hard to date and earlier views were not simply errors. He proposes a different account based on communities and their shared commitments.

• Sections II-V: paradigms and normal science

  A field becomes a mature science when it accepts a paradigm that ends the competition of schools. Normal science articulates the paradigm through measurement, prediction and theoretical refinement, and works like puzzle-solving, with assured solutions and rules. Paradigms guide research even where no explicit rules can be stated.

• Sections VI-VIII: anomaly, crisis and response

  Discoveries begin with awareness of anomaly, as in the cases of oxygen and X-rays. When anomalies become persistent, a crisis loosens the rules of normal science and encourages new theories, as before Copernicus and Lavoisier. Scientists reject a paradigm only when a replacement is available.

• Sections IX-X: revolutions and changes of world view

  Revolutions are non-cumulative episodes in which an older paradigm is replaced by an incompatible one. Kuhn compares them to gestalt switches: after Lavoisier, chemists saw oxygen where their predecessors saw dephlogisticated air, and after Galileo, a swinging stone was seen as a pendulum rather than as constrained fall.

• Section XI: the invisibility of revolutions

  Textbooks and popularisations present only the results of the latest revolution and rewrite the past as a series of contributions to it, so that scientists and the public rarely see that revolutions have occurred.

• Section XII: the resolution of revolutions

  Debates between paradigms are not settled by proof, since the parties disagree about problems, standards and even the meaning of terms. Arguments from problem-solving ability, accuracy and aesthetic fitness persuade gradually, and the community comes over through something like conversion.

• Section XIII and Postscript: progress through revolutions

  Science progresses in that later theories solve more puzzles, but not necessarily toward a final truth; Kuhn compares this to evolution without a goal. The 1969 Postscript introduces the disciplinary matrix and exemplars, discusses incommensurability and translation, and answers charges of relativism.

Characters

• Antoine Lavoisier, historical example

  Chemist whose oxygen theory replaced phlogiston chemistry, Kuhn's central case of a revolution.

• Joseph Priestley, historical example

  Isolated the gas later called oxygen but interpreted it within the phlogiston paradigm.

• Nicolaus Copernicus, historical example

  Whose astronomy arose from a recognised crisis in the Ptolemaic tradition.

• Isaac Newton, historical example

  Whose Principia serves as a paradigm defining normal science in physics.

• Albert Einstein, historical example

  Whose relativity Kuhn uses to show that terms like mass change meaning across a revolution.

• Ludwik Fleck, acknowledged influence

  Polish physician whose 1935 monograph on the history of the concept of syphilis Kuhn credits in his preface.

Lessons

• Most science is careful puzzle-solving

  Kuhn shows that ordinary scientific work is not a constant challenge to fundamentals but disciplined work within an accepted framework. This normal science is what makes precise measurement and detailed knowledge possible, and it is also what makes anomalies visible.

  • What kinds of problems does Kuhn say make up normal science?
  • Why does he think the commitment to a paradigm helps rather than hinders discovery?
  • Can you think of an example of puzzle-solving in a science you have studied?

• Expectation shapes what we notice

  Through the anomalous playing-card experiment and the history of oxygen and X-rays, Kuhn argues that discovery requires recognising that something is wrong with expectation. People trained to see one thing may at first fail to see another.

  • What happened when subjects in the card experiment were shown a red six of spades?
  • Why was it hard to say exactly when oxygen was discovered?
  • How can a student train herself or himself to notice anomalies?

• How histories are written

  Kuhn argues that textbooks rewrite the past so that earlier scientists seem to have worked on present problems. His claim asks readers to study past thinkers in their own terms rather than as imperfect versions of the present.

  • Why, according to Section XI, do revolutions become invisible?
  • What is lost when a textbook presents the history of a science as a straight line?
  • How might this apply to the way students learn any history?

• Reasons that persuade without compelling

  Kuhn holds that choosing between paradigms involves good reasons, such as accuracy and fruitfulness, that persuade without forcing assent. Critics charged him with making science irrational; his Postscript replies that values guide choice even where rules cannot dictate it. The debate remains open.

  • Why does Kuhn say paradigm debates cannot be settled by proof alone?
  • What does he mean by comparing a change of paradigm to a conversion?
  • Is a choice made for good reasons but without a proof still rational?

Context

In the mid-twentieth century philosophy of science in English was shaped by logical empiricism, with its emphasis on the logic of confirmation, and by Karl Popper's account of science as bold conjecture and falsification. The history of science was growing as a discipline, through scholars such as Alexandre Koyré, whom Kuhn admired, and through general-education programmes at Harvard under James B. Conant, where Kuhn taught case histories of science.

Composition

Kuhn conceived the project during his years as a Harvard Junior Fellow and developed it at the Center for Advanced Study in the Behavioral Sciences at Stanford (1958-1959) and at Berkeley. It appeared in 1962 as Volume II, Number 2 of the International Encyclopedia of Unified Science, published by the University of Chicago Press. In his preface Kuhn acknowledges the influence of Koyré, of Ludwik Fleck's Genesis and Development of a Scientific Fact (1935), and of conversations with colleagues. A second, enlarged edition with the Postscript appeared in 1970.

Reception

The book became one of the most cited academic works of the twentieth century and made the word paradigm common far beyond science. Philosophers debated it vigorously: at a 1965 London colloquium, published in Criticism and the Growth of Knowledge (1970), Popper, Imre Lakatos, Paul Feyerabend and others answered Kuhn, and Margaret Masterman distinguished some twenty senses of paradigm in the book. Some readers took it to support relativism about scientific knowledge, a reading Kuhn resisted; others found in it a realistic picture of how scientific communities work. Historians, sociologists and scientists in many fields have used and disputed its categories.

Comparisons

• popper-the-logic-of-scientific-discovery

  Popper describes science as a constant attempt to falsify theories; Kuhn replies that normal science protects its paradigm and that falsification alone does not explain theory change.

• lakatos-the-methodology-of-scientific-research-programmes

  Lakatos's research programmes, with their protected hard core, are a direct attempt to reconcile Popper's rationality with Kuhn's history.

• feyerabend-against-method

  Feyerabend pushes Kuhn's incommensurability further, arguing that no single method governs science.

• polanyi-personal-knowledge

  Polanyi's tacit knowledge, learned by apprenticeship within a community, anticipates Kuhn's exemplars and the role of the scientific community.

• copernicus-on-the-revolutions

  Kuhn's model of crisis and revolution draws heavily on the Copernican case he had studied in The Copernican Revolution.

• lavoisier-elements-of-chemistry

  The chemical revolution of Lavoisier's 1789 treatise is Kuhn's main example of how a new paradigm changes what scientists see.

Quotes

For Students

A reading companion for classical Christian high school students. See the student guide.

Reading Guide

Watch for

• The opening of Section I, where Kuhn says the history of science could change the textbook picture of science.
• The comparison of normal science to puzzle-solving in Section IV, and what makes a good puzzle.
• The account in Section VI of the discovery of oxygen and of the experiment with anomalous playing cards.
• The examples in Section X of how scientists after a revolution see a swinging stone, a gas or a planet differently.
• The closing comparison in Section XIII between scientific progress and Darwinian evolution, which has no fixed goal.

Key terms and names

Paradigm

A shared scientific achievement that defines what problems and methods count in a field; the Postscript separates the broader disciplinary matrix from exemplary problem solutions.

Normal science

Research firmly based on an accepted paradigm, devoted to extending and refining it rather than testing its foundations.

Anomaly

A result that violates the expectations set by the paradigm, such as the X-rays Roentgen did not expect.

Crisis

The state of a field in which anomalies have multiplied and the rules of normal science loosen, as in astronomy before Copernicus.

Incommensurability

Kuhn's claim that rival paradigms differ in their problems, standards and the meaning of their terms, so they cannot be compared point by point on a neutral scale.

Gestalt switch

A sudden change in how a figure is seen, like the duck-rabbit, which Kuhn uses as an image of a change in scientific vision.

Exemplar

A standard worked problem, learned by students, that shows how to apply a theory to nature.

Seminar Questions

1. Comprehension What is a paradigm, and how does its acceptance change a field, according to Sections II and III?
2. Comprehension Why does Kuhn say scientists do not reject a paradigm simply because they find counterinstances?
3. Comprehension How does Kuhn use the story of oxygen to show that discovery is a process rather than a single event?
4. Interpretation What does Kuhn mean when he says that after a revolution scientists work in a different world? Is he speaking literally?
5. Interpretation Kuhn compares a change of paradigm to a religious conversion. What does the comparison illuminate, and where might it mislead?
6. Interpretation Why does Kuhn think textbooks make revolutions invisible, and does that criticism apply to textbooks in your own subjects?
7. Big Question If science does not move toward a fixed goal, as Kuhn suggests in Section XIII, in what sense can it still be called true or progressive?

Faith Connections

• 1 Corinthians 13:9-12 (Scripture)

  We know in part, and now we see through a glass, darkly. Paul's sense that all present knowledge is partial converses with Kuhn's view that each paradigm is provisional, though Paul places the fulfilment of knowledge in seeing face to face.

• Romans 12:2 (Scripture)

  Be ye transformed by the renewing of your mind. Kuhn's image of a scientist coming to see the same world in a new way echoes, at the level of science, the biblical language of a renewed mind.

• Augustine, Confessions VIII (Church Fathers)

  Augustine describes how arguments had persuaded him before his will followed, and how his conversion came at last in the garden at Milan. His account offers a careful study of the experience Kuhn borrows when he speaks of conversion between paradigms.

• John Henry Newman, An Essay in Aid of a Grammar of Assent (1870) (Great Conversation)

  Newman argues that certainty in concrete matters is reached by the convergence of many probabilities judged by the illative sense, not by a single proof. His account bears comparison with Kuhn's claim that good reasons persuade a scientific community without compelling it.

Logic and Rhetoric

Central argument: The history of science shows that research in a mature field is governed by a paradigm that defines its problems and standards. Under a paradigm, normal science solves puzzles and so uncovers anomalies. When anomalies produce crisis and a rival paradigm appears, the choice between them cannot be settled by shared rules alone, because the paradigms differ in their problems, standards and concepts. Therefore scientific change proceeds by revolutions, not simple accumulation, and progress is measured by increasing problem-solving power rather than by approach to a final truth.

Rhetorical device: extended analogy. Kuhn compares scientific revolutions to political revolutions in Section IX and to gestalt switches like the duck-rabbit figure in Section X, using familiar experiences to make the claim that scientists after a revolution see differently (quotes[1]).

Debate: Resolved: That the choice between competing scientific theories is fully rational even when no experiment can decide it.

Writing Prompts

Essay: Kuhn argues that normal science is puzzle-solving within a paradigm and that revolutions replace one paradigm with another that is in important ways incommensurable. Using the chemical revolution of Priestley and Lavoisier as your main case, explain Kuhn's pattern, and evaluate whether his account leaves room for calling Lavoisier's chemistry truer than phlogiston theory.

Comparison with The Logic of Scientific Discovery: Popper says scientists should constantly try to refute their theories; Kuhn says normal science rightly defends its paradigm. Compare the two pictures of the scientist, and argue which better describes how science has actually advanced.

Medical Lens

Kuhn's examples come from physics, chemistry and astronomy, not medicine, but the book has a medical root: in the preface he credits Ludwik Fleck, a Polish physician and microbiologist, whose 1935 monograph Genesis and Development of a Scientific Fact traced how the concept of syphilis and the Wassermann reaction were shaped by a medical thought collective. Kuhn's vocabulary of paradigm shift has since been applied widely, and debated, in medicine and psychiatry, for instance to the germ theory of disease or to changes in psychiatric classification; such applications are later uses of his framework rather than claims in the book.

• Preface

  Kuhn acknowledges Fleck's monograph on the history of the concept of syphilis as anticipating many of his own ideas.

  Syphilis Venereal Physicians Doctors

Creative Prompts

• Classroom

  Show students the duck-rabbit figure, then a short sequence of playing cards that includes a black four of hearts, and discuss how expectation shaped what they saw, as in Kuhn's Section VI.

• Essay

  Choose one revolution Kuhn discusses (Copernican, chemical or Einsteinian) and test his pattern of normal science, anomaly, crisis and revolution against the historical details.

• Dialogue

  Write a debate between Kuhn and Popper at the 1965 London colloquium on whether normal science is a danger or a strength.

Further Reading

• The Copernican Revolution, Thomas S. Kuhn

• The Essential Tension, Thomas S. Kuhn

  Includes the essay on objectivity, value judgment and theory choice.

• Genesis and Development of a Scientific Fact, Ludwik Fleck

• Criticism and the Growth of Knowledge, Imre Lakatos and Alan Musgrave (eds.)

• Thomas Kuhn: A Philosophical History for Our Times, Steve Fuller