The Structure of Scientific Revolutions

1. Introduction

The Structure of Scientific Revolutions (1962; 2nd ed. 1970) is Thomas S. Kuhn’s influential study of how the natural sciences develop and change over time. Drawing on detailed historical case studies, Kuhn challenges the then‑dominant view—shared in various forms by logical empiricists and critical rationalists—that science advances through a steady, cumulative accumulation of verified facts or falsified hypotheses.

Kuhn instead proposes that mature sciences typically alternate between two distinct phases. In periods of normal science, research is guided by a shared paradigm—a constellation of exemplary achievements, methods, standards, and assumptions that defines legitimate problems and acceptable solutions for a particular scientific community. Over time, however, persistent anomalies may undermine confidence in the prevailing framework, eventually producing a crisis and, in some cases, a scientific revolution in which one paradigm is replaced by another that is partly incompatible with it.

The book is both descriptive and meta‑philosophical. It offers a pattern (or “structure”) of scientific development and also reflects on what this pattern implies for central philosophical questions about evidence, rationality, progress, and the status of scientific knowledge. Kuhn introduces a vocabulary—“paradigm,” “normal science,” “revolution,” incommensurability, and “paradigm shift”—that has become central not only in philosophy and history of science but also in wider intellectual and popular discourse.

Subsequent debate has centered on how far Kuhn’s claims about discontinuity, theory‑ladenness of observation, and non‑algorithmic theory choice challenge traditional accounts of scientific rationality and realism. While interpretations differ substantially, Structure is widely regarded as a key text in the “historical turn” in philosophy of science and as a landmark in twentieth‑century reflections on scientific change.

2. Historical Context

Kuhn’s work emerged in a mid‑twentieth‑century intellectual landscape shaped by logical empiricism, post‑war scientific prestige, and growing interest in the actual history of scientific practice.

Philosophy of Science in the 1950s–1960s

Logical empiricists such as Rudolf Carnap and Carl Hempel dominated Anglophone philosophy of science. They emphasized:

• Logical reconstruction of scientific theories
• The centrality of observation language and confirmation
• A cumulative picture of scientific progress

Karl Popper’s critical rationalism provided a prominent alternative, stressing falsifiability and conjectural knowledge, but likewise retained a strong commitment to rational reconstruction and continuity in scientific growth.

Kuhn’s historically grounded account contrasted with both traditions by foregrounding discontinuous change, the role of scientific communities, and the centrality of exemplars rather than explicit rules.

The International Encyclopedia of Unified Science

Structure first appeared as a monograph within the International Encyclopedia of Unified Science project, sponsored by logical empiricists who aimed to unify scientific knowledge through logical analysis. Kuhn’s contribution thus appeared inside a series associated with the very methodology he would call into question, lending his proposals particular resonance and, for some contemporaries, irony.

The “Historical Turn” and Related Figures

Kuhn’s work is often situated alongside a broader “historical turn” in philosophy of science. Contemporaries and near‑contemporaries such as:

• Norwood Russell Hanson (on theory‑ladenness of observation),
• Paul Feyerabend (methodological pluralism),
• Imre Lakatos (research programmes),

likewise integrated historical case studies into philosophical analysis, though they drew partly different conclusions.

In parallel, historians of science—including Alexandre Koyré and Rupert Hall—were advancing sophisticated, context‑sensitive narratives of major scientific episodes. Kuhn’s own training in both physics and history of science placed him at the intersection of these developments, enabling him to exploit detailed historical scholarship to challenge prevailing philosophical models of scientific rationality and development.

3. Author and Composition

Thomas Samuel Kuhn (1922–1996) was an American historian and philosopher of science with initial training in theoretical physics. His dual expertise—scientific and historical—shaped both the content and method of The Structure of Scientific Revolutions.

Intellectual Background

Kuhn studied physics at Harvard, completing his PhD in 1949. While teaching an undergraduate course on the history of science, he encountered Aristotelian physics and reportedly experienced a cognitive “gestalt switch” when he realized that historical scientific texts made sense only when read within their original conceptual frameworks. This experience is often cited, including by Kuhn himself, as formative for his later idea of paradigm‑dependent perception and understanding.

Transitioning from physics to history of science, Kuhn conducted detailed studies on the Copernican revolution, culminating in his book The Copernican Revolution (1957). These historical investigations convinced him that scientific development was neither linear nor simply accumulative, and they provided many of the case materials later used in Structure.

Path to Structure

The immediate antecedents of Structure were Kuhn’s Berkeley lectures on the history of science (1956–1957) and his 1959 essay “The Essential Tension,” which already contrasted conservative, tradition‑bound aspects of research with innovation and revolutionary change.

The composition of Structure took place roughly between 1959 and 1961, while Kuhn was at the University of California, Berkeley. During this period, he systematized insights from case studies (e.g., Copernican astronomy, the emergence of Newtonian mechanics, Lavoisier’s chemistry) into a general model of scientific development. Drafts were circulated among colleagues, including philosophers and historians of science, and shaped by exchanges within the milieu of the International Encyclopedia of Unified Science.

Authorial Aims

Kuhn’s explicit aim in Structure was to draw philosophical lessons from historical practice rather than to offer a purely prescriptive methodology. He sought to:

• Show that historical episodes in science exhibit a recurring pattern of normal science, crisis, and revolution
• Argue that understanding science requires attention to the commitments and training of specific scientific communities

Later reflections, especially in the 1970 Postscript, indicate that Kuhn also regarded the book as a corrective to overly abstract, logic‑centered views of science then current in analytic philosophy.

4. Publication and Textual History

The Structure of Scientific Revolutions has a relatively straightforward but philosophically significant textual history, marked primarily by the addition of a substantial Postscript in the second edition.

Initial Publication (1962)

The work was first published in 1962 by the University of Chicago Press as Volume II, Number 2 of the International Encyclopedia of Unified Science. Its placement in this series linked it directly to the logical empiricist project of scientific unification, even as it questioned central tenets of that movement.

Kuhn revised his manuscript in response to editorial feedback but the 1962 text already contained the central ideas of paradigms, normal science, anomalies, crisis, and revolutions.

Second Edition and 1969 Postscript (1970)

Following intense discussion in the 1960s, Kuhn prepared a second, “enlarged” edition, published in 1970. The body of the text remained largely unchanged, but Kuhn added a lengthy Postscript (written in 1969) in which he:

• Clarified his use of “paradigm” and introduced the related concept of “disciplinary matrix”
• Elaborated his account of incommensurability and theory comparison
• Responded to charges of relativism and irrationalism

Modern English editions generally reproduce this 1970 text.

Later Printings and Translations

The work has been widely translated. While translations are generally faithful, commentators sometimes note variation in how terms like “paradigm,” “normal science,” and “incommensurability” are rendered, which can affect local receptions.

Manuscripts and Archival Status

Kuhn’s drafts, correspondence, and lecture notes related to the composition of Structure are preserved in archival collections (e.g., at MIT and elsewhere). Historians and philosophers have used these materials to trace the evolution of Kuhn’s terminology and arguments, though no alternative “critical edition” of the text has been produced.

5. Structure and Organization of the Work

Kuhn organizes The Structure of Scientific Revolutions into a sequence of chapters that trace a purportedly recurrent pattern in the development of mature sciences. The work progresses from an initial methodological reflection to a systematic account of different phases of scientific practice.

Overall Layout

The book consists of:

• A Preface, where Kuhn explains the origins of the study in his historical work
• Thirteen numbered chapters
• A Postscript—1969 (added to the 1970 second edition)

Thematic Progression

The chapters follow a relatively linear argumentative trajectory:

The sequence is designed to move from description of everyday scientific activity to analyses of exceptional episodes and, finally, to reflections on long‑term development.

Internal Coherence

Kuhn repeatedly returns to the same historical case studies—particularly the Copernican revolution, the transition to Newtonian mechanics, and Lavoisier’s chemical revolution—using them across chapters to illustrate different aspects of the same structural pattern (e.g., normal practice, emergent anomalies, revolutionary transformation).

The 1970 Postscript does not alter the chapter structure but supplements it by:

• Systematizing Kuhn’s conceptual apparatus (e.g., paradigm vs. disciplinary matrix, exemplars)
• Refining the account of theory comparison and translation

Thus, the work’s organization is both narrative (following the life cycle of a paradigm) and reflexive (returning at the end to conceptual clarification).

6. Central Arguments and Thesis

Kuhn’s central thesis is that the development of mature scientific disciplines is neither purely cumulative nor adequately captured by standard logical models of confirmation or falsification. Instead, it exhibits a recurrent pattern structured by the rise, dominance, crisis, and replacement of paradigms.

Core Claims

1. Paradigm‑Dependent Normal Science
   Scientific research is organized around paradigms—shared exemplars, concepts, methods, and standards. These paradigms define legitimate problems and constrain acceptable solutions, so that most research takes the form of puzzle‑solving within a relatively rigid framework.

2. Non‑Cumulative Scientific Revolutions
   Over time, persistent anomalies accumulate. When these anomalies become particularly salient and resistant to standard problem‑solving strategies, a crisis may ensue. In some cases, this crisis leads to the emergence of an alternative paradigm, triggering a scientific revolution in which the basic conceptual and methodological framework of a field changes.

3. Incommensurability and Theory Choice
   Successive paradigms are often incommensurable in the sense that they involve different conceptual schemes, standards, and exemplary problems, making direct, theory‑neutral comparison problematic. Theory choice in revolutionary periods is therefore not governed by a single algorithmic rule but by a combination of shared values (e.g., accuracy, simplicity, coherence) and persuasive argument within a scientific community.

4. Reconceptualized Scientific Progress
   Although Kuhn denies simple cumulative growth of truths, he maintains that science can still be said to progress. Progress is characterized as increased problem‑solving effectiveness and the capacity to generate and resolve new puzzles, rather than as straightforward approximation to a fixed, theory‑independent reality.

Implications

These arguments jointly challenge several entrenched views: that observation is theory‑neutral; that there is a unique, context‑free scientific method; and that scientific change is best represented as a smooth accumulation of verified propositions. Kuhn instead proposes a historically informed picture in which scientific knowledge is structured by evolving frameworks whose adoption involves both empirical and non‑empirical considerations.

7. Key Concepts: Paradigms, Normal Science, and Revolutions

Kuhn’s analysis hinges on a cluster of interrelated concepts that describe different phases and structures of scientific activity.

Paradigms

In the main text, paradigm has multiple but related senses. It designates:

• Concrete exemplary achievements (e.g., Newton’s Principia, Lavoisier’s chemistry) that serve as models for further work
• The broader constellation of commitments—conceptual, methodological, and metaphysical—shared by a scientific community

Paradigms define what counts as a legitimate problem, what methods are appropriate, and what counts as a satisfactory solution. They are historically situated and community‑specific rather than universal.

Normal Science

Normal science is research “firmly based upon one or more past scientific achievements” that a relevant community regards as paradigmatic. It is characterized by:

• Puzzle‑solving: Scientists address well‑defined problems whose solutions are anticipated in principle
• Conservatism: Fundamental assumptions are taken for granted rather than questioned
• Specialization: Work often involves extending the paradigm’s reach into new domains or refining its quantitative predictions

Normal science is highly productive but also narrow, aiming to articulate and extend, not to overthrow, the governing framework.

Scientific Revolutions

A scientific revolution occurs when the existing paradigm is displaced by a new, incompatible one. Kuhn emphasizes that:

• Revolutions are non‑cumulative: previously accepted concepts and standards may be abandoned or reinterpreted
• They reorganize the disciplinary matrix, changing not just particular theories but also exemplary problems, methods, and standards
• They involve intense debate over both empirical adequacy and methodological or aesthetic virtues (e.g., simplicity, coherence)

Revolutions mark transitions between periods of normal science and reconfigure what counts as scientific fact, problem, and explanation.

8. Anomalies, Crisis, and Theory Change

Kuhn’s account of theory change centers on the dynamics by which anomalies accumulate, become problematic, and sometimes precipitate crisis and revolutionary transformation.

Anomalies within Normal Science

Within normal science, an anomaly is a recalcitrant discrepancy between what the paradigm leads scientists to expect and what they observe or calculate. At first, such discrepancies are typically:

• Treated as puzzles to be solved within the existing framework
• Attributed to experimental error, incomplete understanding, or auxiliary hypotheses

Normal science expects anomalies; their existence does not by itself threaten the paradigm.

From Anomaly to Crisis

Anomalies may contribute to a crisis when they:

• Persist despite repeated efforts and methodological refinement
• Affect central, not peripheral, aspects of the paradigm
• Acquire symbolic weight as emblematic of the paradigm’s limitations

Historical examples Kuhn discusses include the anomalous motion of Mercury’s perihelion for Newtonian mechanics and problems with phlogiston theory in chemistry. A crisis is marked by growing doubt, proliferation of speculative proposals, and increased discussion of fundamentals.

Emergence of New Theories

In a crisis, scientists may develop competing theoretical frameworks that attempt to resolve anomalies by reconceptualizing basic entities, laws, or measurement standards. These nascent frameworks:

• Often begin as bold conjectures or partial analogies
• May initially be less developed than the old paradigm but promise to handle key anomalies better
• Reconfigure what counts as a legitimate problem and acceptable solution

Theory change, in Kuhn’s sense, involves not only replacement of specific laws but transformation of the broader paradigm. The process is gradual, involving debate, experimentation, and pedagogical shifts, but its outcome—a new normal science under a different paradigm—represents a qualitative change in the field’s conceptual and methodological structure.

9. Incommensurability and Theory‑Ladenness

Kuhn’s notions of incommensurability and theory‑ladenness of observation articulate why, on his view, competing paradigms cannot be compared in a wholly neutral, framework‑independent way.

Theory‑Ladenness of Observation

Kuhn argues that what scientists “see” and report is shaped by their training and paradigmatic commitments. For example:

• The same experimental display may be described using different concepts depending on one’s theoretical background.
• Novices and experts, or adherents of rival paradigms, may disagree on what counts as a salient feature or even as a “datum.”

This theory‑ladenness suggests that observation statements are not fully independent of theoretical assumptions, challenging the idea of a pure observation language shared across paradigms.

Incommensurability

Incommensurability refers, in Kuhn’s usage, to the lack of a common measure between successive paradigms. It manifests in several ways:

• Semantic change: Key terms (e.g., “mass,” “planet,” “chemical element”) may shift in meaning across paradigms.
• Differing problem‑fields: What counts as important or even intelligible problems can vary.
• Distinct standards: Criteria like simplicity or explanatory power may be understood differently or applied to different aspects of theories.

Kuhn does not claim that communication across paradigms is impossible, but that translation is partial and interpretive, not mechanical.

These ideas underpin Kuhn’s claim that theory choice during revolutions cannot be reduced to straightforward comparison of rival theories against a fixed body of neutral observations. Instead, it involves negotiation over both empirical fit and the very standards by which such fit is judged.

10. Famous Analogies and Illustrative Passages

Kuhn employs vivid analogies and carefully chosen passages to convey the experiential and conceptual dimensions of scientific change.

Duck–Rabbit Gestalt Switch

One of the most cited analogies is the duck–rabbit figure from Gestalt psychology. Kuhn uses it to illustrate how scientists, upon adopting a new paradigm, may “see” the same data differently:

"

The historian of science may be tempted to exclaim that when paradigms change, the world itself changes with them.

— Thomas S. Kuhn, The Structure of Scientific Revolutions, ch. X

The analogy is meant to capture a change in perception and interpretation, not in the physical stimulus itself.

Puzzle‑Solving and Jigsaw Puzzles

To characterize normal science, Kuhn likens scientific research to solving jigsaw puzzles:

"

The puzzles that normally occupy scientists are assumed to have solutions. That assumption is, in fact, an essential part of puzzle definition.

— ibid., ch. IV

This analogy underscores the structured, constrained, and expectation‑laden nature of normal scientific work.

Incommensurability and Translation

Kuhn compares translation between paradigms to translation between natural languages, where terms only partially overlap in meaning. He suggests that moving between frameworks involves a process more akin to learning a new language or acquiring a new set of exemplars than to mechanically substituting synonyms.

Neurath’s Ship

In the Postscript, Kuhn aligns his view with Otto Neurath’s ship at sea metaphor:

"

We are like sailors who must rebuild their ship on the open sea, never able to dismantle it in dry‑dock and to reconstruct it there out of the best materials.

— alluded to in Structure, Postscript

Kuhn uses this image to convey the idea that scientists revise their frameworks while still relying on portions of them, without ever achieving a completely theory‑independent standpoint.

These analogies have played a central role in how readers interpret Kuhn’s claims about perception, rationality, and the nature of scientific change.

11. Philosophical Method and Use of History

Kuhn’s methodological approach is distinctive in its integration of detailed historical scholarship with philosophical analysis of science.

History as a Source of Philosophical Insight

Kuhn treats the history of science not merely as illustrative material but as a primary tool for understanding scientific practice. He argues that:

• Standard philosophical accounts often abstract away from how science has actually developed.
• Historical case studies reveal patterns—such as periods of normal science and revolutionary upheaval—not captured by logical reconstructions.

Accordingly, much of Structure is built around narratives of specific episodes (e.g., Copernican astronomy, Newtonian mechanics, Lavoisier’s chemistry, the rise of quantum theory) from which Kuhn generalizes.

Descriptive, Not Prescriptive, Method

Kuhn presents his project as primarily descriptive of actual scientific practice rather than prescriptive of an ideal method. He aims to:

• Reconstruct the “internal” logic of scientific development as it appears in historical records
• Identify recurring structures in scientists’ behavior, reasoning, and institutional practices

This stance distinguishes him from philosophers who propose normative rules for theory choice or justification independently of historical evidence.

Community‑Based Perspective

Kuhn focuses on scientific communities as the units of analysis. His method attends to:

• Training practices (e.g., textbook use, problem sets)
• Shared exemplars and traditions
• Professional norms and gatekeeping mechanisms (journals, peer review)

This sociologically informed orientation anticipates later work in sociology of scientific knowledge and science and technology studies.

Relation to Logical Analysis

Although critical of purely formal models, Kuhn does not reject logical analysis altogether. Rather, he suggests that:

• Logical relations between theories and evidence must be understood within the context of paradigms and disciplinary matrices.
• Philosophical reflection should be constrained by, and responsive to, historical and sociological findings.

This mixed method—historical, sociological, and conceptual—has been both influential and contested in subsequent philosophy of science.

12. The 1970 Postscript and Conceptual Clarifications

The Postscript—1969, added to the 1970 edition, responds to misunderstandings and criticisms that emerged after the first publication. It refines several core concepts and clarifies Kuhn’s stance on rationality and relativism.

Paradigm and Disciplinary Matrix

Critics had noted that Kuhn used “paradigm” in multiple senses. In the Postscript, he:

• Acknowledges this multiplicity
• Introduces “disciplinary matrix” for the broader set of shared elements (symbolic generalizations, models, values, exemplars) that characterize a scientific community
• Reserves “exemplars” for the concrete problem‑solutions that guide practice

This terminological refinement aims to distinguish between concrete models and the more diffuse network of commitments.

Incommensurability Revisited

Kuhn clarifies that incommensurability does not entail incomparability or communication breakdown. Instead, it signals:

• Partial untranslatability due to shifts in meaning and reference
• The need for interpretive work when comparing theories across paradigms

He emphasizes that scientists do, in practice, compare rival frameworks, but that this process cannot be captured by a simple algorithm.

Theory Choice and Shared Values

Responding to charges of irrationalism, Kuhn discusses values that guide theory choice across paradigms, such as:

• Accuracy
• Consistency
• Scope
• Simplicity
• Fruitfulness

He argues that while these values are shared, they are applied with different weights and interpretations in particular contexts, leading to reasonable disagreement without implying arbitrariness.

Realism and Relativism

Kuhn also addresses concerns about relativism. He denies that his view implies that all paradigms are equally good or that there is no sense in which science progresses. Instead, he reiterates that progress is best understood as increasing problem‑solving power, while allowing that talk of truth may be retained but is more complex than traditional realist pictures suggest.

Overall, the Postscript has been seen as both a clarification and, by some commentators, a partial softening or systematization of themes that in the original text appeared more radical or ambiguous.

13. Reception and Major Criticisms

The Structure of Scientific Revolutions quickly became a focal point of debate across philosophy, history, and sociology of science. Its reception has been both highly enthusiastic and sharply critical.

Early Reactions

Initially, many philosophers associated with logical empiricism viewed Kuhn’s work as a challenge to rational reconstruction and cumulative views of science. At the same time, historians of science and some philosophers welcomed his historically grounded approach and attention to actual scientific practice.

Major Lines of Criticism

Commentators have raised several recurring objections:

Supportive Responses and Developments

Other scholars have defended or elaborated Kuhn’s claims. For example:

• Lakatos developed the methodology of research programmes as a modification rather than rejection of Kuhn’s insights.
• Sociologists of scientific knowledge drew on Kuhn to argue for the centrality of social factors in science.
• Later interpreters (e.g., Paul Hoyningen‑Huene, Alexander Bird) have offered systematic reconstructions aimed at addressing concerns about ambiguity and relativism.

Despite disagreements, there is broad consensus that Structure reshaped the agenda of philosophy of science, compelling critics and supporters alike to engage with its central themes.

14. Influence on Philosophy, History, and Sociology of Science

Kuhn’s work has had wide‑ranging and enduring influence across multiple disciplines concerned with science.

Philosophy of Science

In philosophy, Structure is often credited with initiating or consolidating the historical turn. Its impact includes:

• Shifting attention from logical reconstruction of isolated theories to the dynamics of whole research traditions and scientific communities.
• Inspiring alternative models of scientific change, such as Lakatos’s research programmes and Feyerabend’s methodological pluralism.
• Stimulating debates on realism vs. anti‑realism, rationality, and the nature of scientific progress, with many later positions (e.g., structural realism, naturalized epistemology) framed partly in response to Kuhn.

History of Science

For historians, Kuhn’s emphasis on paradigms and revolutions:

• Encouraged more contextual and practice‑oriented studies, focusing on laboratories, instruments, and training.
• Provided a conceptual vocabulary for describing large‑scale shifts (e.g., the “Newtonian revolution,” “Darwinian revolution”), though some historians have argued for more fine‑grained or pluralistic periodizations.
• Raised methodological questions about the extent to which historians should impose patterns such as “normal science” and “crisis” on diverse historical episodes.

Sociology of Science and STS

In sociology of scientific knowledge and science and technology studies (STS), Kuhn’s focus on communities and shared commitments proved foundational:

• The idea that what counts as a fact or legitimate problem is shaped by community standards influenced social constructivist approaches.
• Scholars such as Barry Barnes, David Bloor, and later Bruno Latour drew on Kuhn while extending social and cultural analysis of scientific practice beyond his framework.
• Concepts analogous to paradigms (e.g., “thought collectives,” “actor‑networks”) have been developed in dialogue with Kuhnian themes.

Beyond the Academy

Kuhn’s terminology—especially “paradigm shift”—has migrated into management theory, political discourse, education, and popular culture. While such uses often simplify or detach the concept from its original philosophical context, they testify to the work’s broad cultural resonance.

Overall, Kuhn’s influence is evident both in direct appropriations of his concepts and in the extent to which later theories of scientific change define themselves in relation to his account.

15. Legacy and Historical Significance

The Structure of Scientific Revolutions is widely regarded as one of the most important twentieth‑century works on science, with a legacy that spans multiple disciplines and popular discourse.

Canonical Status

Within philosophy of science, Kuhn’s book has become a canonical text. It is routinely:

• Assigned in undergraduate and graduate curricula
• Used as a reference point for debates about scientific rationality, realism, and methodology
• Cited in discussions of the “historical turn” and the integration of empirical studies into epistemology

The work’s vocabulary—paradigms, normal science, revolution, incommensurability—has become standard, even among those who reject aspects of Kuhn’s framework.

Reshaping the Image of Science

Kuhn’s legacy includes a transformed public and academic image of science:

• He challenged linear, triumphalist narratives of scientific progress, highlighting the role of discontinuity, controversy, and conceptual change.
• He emphasized that scientific knowledge is produced by communities with shared training and values, not solely by isolated geniuses or abstract methods.
• He contributed to the view that scientific development is historically and socially embedded.

These themes have influenced not only philosophy and history but also educational approaches to science and public understanding of its fallibility and dynamics.

Continuing Debates

Kuhn’s ideas continue to provoke debate over:

• The extent and nature of incommensurability
• Whether his account supports forms of epistemic relativism or is compatible with scientific realism
• How well the normal science/revolution schema fits disciplines such as biology, social sciences, or contemporary interdisciplinary fields

Subsequent work—both critical and sympathetic—has refined, reformulated, or contested his theses, ensuring that his book remains a living point of reference rather than a closed doctrine.

Broader Cultural Impact

Finally, the diffusion of terms like “paradigm shift” into everyday language has made Kuhn’s influence visible far beyond specialist circles. While this popularization often abstracts from his detailed historical and philosophical analysis, it indicates how his rethinking of conceptual change has shaped broader conversations about innovation, crisis, and transformation in many domains of human activity.