The Structure of Scientific Revolutions

Citation

Kuhn, T. S. (2012). The Structure of Scientific Revolutions (4th ed., 50th anniversary edition; introductory essay by I. Hacking). University of Chicago Press.

Chapter Summary

The book first appeared in 1962 and was extended with a postscript dated 1969. According to the Stanford Encyclopedia of Philosophy (SEP), the second edition carrying that postscript came out in 1970. This fourth edition keeps Kuhn's text and adds an introductory essay by Ian Hacking. The publisher describes the essay as clarifying terms such as paradigm and incommensurability and as keyed to the separate sections of the book. The book consists of a preface, thirteen short chapters (I–XIII) and the "Postscript-1969." It is short enough to read in a few sittings.

Context and Argument

Kuhn argues that science does not grow by the steady accumulation of facts. A mature science works within a shared paradigm, and its normal activity is puzzle-solving. Persistent anomalies can produce a crisis. A revolution then replaces one paradigm with another in a way that cannot be settled by logic and experiment alone. The chapters follow this cycle in order. The SEP's summary of the book follows the same sequence: normal science as puzzle-solving, paradigms, anomaly leading to crisis and revolution, incommensurability, Kuhn-loss, and a non-teleological, evolutionary picture of progress.

Chapter I: Introduction: A Role for History

The opening chapter argues that history can change the image of science. Kuhn sets aside two things:

• the picture of science as a linear accumulation of facts, and
• the sharp separation of the context of discovery from the context of justification.

In their place he proposes to look at actual episodes of research.

Chapters II–V: The Route to Normal Science; The Nature of Normal Science; Normal Science as Puzzle-solving; The Priority of Paradigms

These chapters describe how a field reaches maturity. In a pre-paradigm period, competing schools disagree over fundamentals. Then a remarkable achievement draws consensus around it, often embodied in a text such as Ptolemy's Almagest, Newton's Principia or Lavoisier's chemistry. Normal science works on puzzles the paradigm defines, with confidence that solutions exist. The chapter on the priority of paradigms argues that shared exemplars, rather than explicit rules, are what guide research.

Chapters VI–VIII: Anomaly and the Emergence of Scientific Revolutions; Crisis and the Emergence of Scientific Theories; The Response to Crisis

Anomalies are results that the paradigm fails to accommodate. Most are set aside or absorbed. When they undermine the practice of normal science, a crisis develops. The chapters then describe how scientists respond. They search for alternatives, but they stay committed to the existing paradigm until a credible rival is available.

Chapters IX–XII: The Nature and Necessity of Scientific Revolutions; Revolutions as Changes of World View; The Invisibility of Revolutions; The Resolution of Revolutions

The core chapters make four claims:

• Revolutions are non-cumulative changes, in which something earlier achievements explained may be lost.
• After a revolution, scientists work in a different world of perception and concepts.
• Textbooks hide such changes by rewriting history.
• The choice between rival paradigms is made by the scientific community, not by a rule that compels agreement.

Chapter XIII: Progress through Revolutions

Kuhn asks in what sense science makes progress if revolutions are not cumulative. He argues that a new paradigm must solve outstanding problems while preserving much of the problem-solving power of its predecessor. He frames progress in evolutionary terms, as improved problem-solving rather than movement toward a final truth. The SEP stresses that this evolutionary picture is deliberately non-teleological.

Postscript-1969

In the postscript Kuhn replies to critics and reworks the term "paradigm." He distinguishes two senses:

• the shared commitments of a community, which he calls the "disciplinary matrix," and
• the narrower sense of exemplary problem solutions.

He calls paradigms in this narrower sense the most novel and least understood aspect of the book. The SEP treats this exemplar/disciplinary-matrix distinction as the postscript's main clarification.

Key Concepts

Normal science

• Paradigm: in the broad sense, the shared commitments of a scientific community (the "disciplinary matrix"). In the narrower sense, exemplary achievements that serve as models for further work (exemplars).
• Normal science: research based on a paradigm, treated as puzzle-solving.
• Puzzle: a problem whose solution is expected to be possible by familiar methods.

Crisis and revolution

• Anomaly and crisis: an anomaly is a result the paradigm does not accommodate. A crisis is a widespread loss of confidence that follows when anomalies undermine normal practice.
• Scientific revolution: a non-cumulative change of paradigm.
• Incommensurability: the claim that rival paradigms differ in concepts, standards and problems, so that no neutral comparison is available. The SEP notes that Kuhn later reworked this into a narrower, "taxonomic" version.
• Kuhn-loss: explanatory achievements that a successor theory does not retain.
• Progress without a goal of truth: improvement understood as increased puzzle-solving power, not nearness to truth.

Critical Analysis

Strengths

• A clear structure. The chapter order follows the cycle it describes, from pre-paradigm science through normal science, crisis and revolution to resolution. The argument can be followed step by step, and courses can divide the reading along the same lines (see "Common course assignments" below).
• Range of examples. Reviewing the anniversary edition in Nature, David Kaiser praised Kuhn's "fascinating mix of examples from psychology, history, philosophy, and beyond." He described Hacking's introduction as a helpful guide to some of the thornier philosophical issues. The publisher's page also quotes reviews from the Chronicle of Higher Education and the Guardian.
• Support for readers. Hacking's essay is organized to correspond to the sections of the book and clarifies terms that became common currency. The 1969 postscript answers criticism and refines the central term.
• A concrete target. Kuhn sets his account against the cumulative picture and against Popper's falsificationism. This gives students a clear contrast to work with.
• A productive provocation. The book generated a whole literature of responses. The SEP discusses the 1970 volume edited by Imre Lakatos and Alan Musgrave in connection with criticism of Kuhn. Some courses follow Kuhn directly with these critics (see the Montana course below).

Limitations

• The picture of scientific change has been disputed. The SEP (§7.1) reports Stephen Toulmin's objection that revisionary change is more common and less dramatic than Kuhn supposes. It also notes that discoveries such as the structure of DNA do not fit Kuhn's pattern of anomaly followed by crisis.
• Charges of irrationalism and relativism. Critics including Dudley Shapere, as the SEP reports, pressed the relativist implications of Kuhn's account of paradigm choice. Lakatos framed his methodology of research programmes as a rival account. He charged that Kuhn reduced theory change to a matter of "mob psychology."
• Key terms are unstable. Kuhn himself calls paradigms the most novel and least understood aspect of the book. Incommensurability has been criticized as non-existent, or as less significant than he claimed. Kuhn's own account of it changed in later work toward a taxonomic version, according to the SEP.
• Rooted in physical science. The publisher notes that Kuhn wrote when physics ruled the sciences. The examples that carry the argument are mainly from astronomy, physics and chemistry, so readers from other fields should test the pattern against their own cases.
• Open to misreading. Kuhn remarked that personalities and nationalities can matter in a revolution. Some sociologists developed this into the claim that social factors always determine outcomes. Kuhn rejected that reading, and the SEP (§7.3) records his repudiation of the "Strong Programme" in the sociology of knowledge.

Where It Fits in the Course

This is a primary text on theory change, so it works well after one introductory book and before more specialized ones.

Several introductions give the setting, though they are not on this site:

• Samir Okasha's short introduction.
• Peter Godfrey-Smith's survey, which follows the century of debate from logical empiricism through Popper, Kuhn, Lakatos and Feyerabend to the sociology of science. In it, Kuhn appears as one stage in a longer story.
• Alan Chalmers's book.

Alex Rosenberg and Lee McIntyre's textbook also discusses method and theory change. Like Chalmers, it can be used to compare Kuhn with other accounts.

Two of the courses listed under "Common course assignments" below move from Kuhn to Lakatos, and the Montana course continues to Laudan and Feyerabend.

On this site, Bas van Fraassen's The Scientific Image (the-scientific-image-van-fraassen.md) is a good partner. Kuhn describes how sciences change and what scientists do within and across paradigms. Van Fraassen asks which attitude to adopt toward the theories that result. Reading them together shows how a historical account of theory change and a philosophical account of belief and acceptance can complement each other.

How to Use This Book

The book assumes no technical background, though some acquaintance with the history of science or an introductory philosophy of science course helps.

For a first reading:

1. Take the thirteen chapters in order.
2. Read the Postscript immediately afterwards, because it clarifies what "paradigm" means and answers common objections.
3. Read Hacking's introductory essay either afterwards, as a commentary, or section by section alongside the book.

On emphasis: Chapters II–IV and VI–IX are the core. Chapters X–XI are essential if the course discusses perception, world change or incommensurability. Chapter V can be read more quickly.

Common course assignments

Three published syllabi show different ways of dividing the book:

• University of Montana, PHIL 501. Assigns the book in four successive reading blocks: Chapters 1–5, then 6–9, then 10–13, then the Postscript. It then turns to Lakatos, Laudan and Feyerabend ("Consolations for the Specialist" and Against Method).
• UNLV, Phil 430 (Wood). Starts with Hacking's introduction together with Kuhn's Preface and Chapters I–II. It then proceeds through I–V, VI–VII, VIII–X, and XI–XIII plus the Postscript, before moving to Lakatos. This is a model for reading Hacking first as orientation.
• Stanford, CS 378. For a computer-science audience, assigns only Chapter II and Chapter VI. If you need a minimal selection, the route to normal science and the chapter on anomaly carry the basic idea.

Edition notes

Use the University of Chicago Press 50th anniversary (4th) edition, ISBN 9780226458120. It adds Hacking's essay, keyed to the book's sections, and retains the Postscript-1969, which first appeared in the second edition in 1970.

Exercise

A useful exercise is to take a historical episode, such as the shift from Ptolemaic to Copernican astronomy, and place each stage on Kuhn's cycle. Then ask which stage is hardest to identify. Compare the result with how Popper's falsificationism would describe the same case. Then repeat the test with a case the SEP flags as a poor fit, such as the discovery of the structure of DNA, and weigh Toulmin's suggestion that gradual revision is the more common pattern. If the course continues to Lakatos, re-describe the same episode in terms of competing research programmes and compare the two accounts.