Introductory Essay by Ian Hacking Preface 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. Anomaly and the Emergence of Scientific Revolutions VII. Crisis and the Emergence of Scientific Theories VIII. The Response to Crisis IX. The Nature and Necessity of Scientific Revolutions X. Revolutions as Changes of World View XI. The Invisibility of Revolutions XII. The Resolution of Revolutions XIII. Progress through Revolutions Postscript-1969 Index