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 Discoveries -- 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 Resolutions of Revolutions -- XIII. Progress through Revolutions.