The Structure of Scientific Revolutions (Summary)
What if scientific progress isn't a steady, rational march toward truth? Imagine that for centuries, the world's greatest minds saw a swinging pendulum and believed it was an object trying to find its 'natural' state of rest. Then, almost overnight, a new generation saw the exact same pendulum and perceived it as an object governed by external forces. The object didn't change, but the entire reality of the scientists observing it did. This is a 'paradigm shift,' and Kuhn argues it's how science really works: not by adding new facts, but through violent, irrational revolutions that overthrow entire worldviews.
Most Science Is Just Puzzle-Solving, Not Discovery
The day-to-day work of scientists, or 'normal science,' isn't about making groundbreaking discoveries. It's about solving puzzles within the rules of an established framework, or 'paradigm.' The goal is to force nature into the conceptual box supplied by the paradigm, not to challenge the box itself.
After Isaac Newton established his laws of motion, astronomers for the next two centuries didn't question his framework. Instead, they used it to solve puzzles like calculating the precise orbit of Mars or predicting the return of Halley's Comet. When a prediction was slightly off, they didn't doubt Newton's laws; they assumed their calculations or measurements were flawed.
Revolutions Begin When Puzzles Become Scandals
A paradigm shift begins when the existing framework repeatedly fails to solve a critical puzzle, creating an 'anomaly.' As anomalies pile up and resist all attempts at resolution, a state of crisis emerges, opening the door for a completely new and rival paradigm.
By the late 19th century, classical physics couldn't explain why the orbit of Mercury wasn't quite what Newton's laws predicted. This was a persistent anomaly. This, along with other puzzles like the nature of black-body radiation, created a crisis that the old paradigm couldn't handle, ultimately paving the way for Einstein's theory of relativity—a new paradigm that treated the anomalies as central proofs.
Scientists in Different Paradigms Live in Different Worlds
Proponents of competing paradigms don't just disagree; they are 'incommensurable.' They use the same words (e.g., 'mass') to mean different things, look at the same data and see different evidence, and adhere to different standards of proof. They essentially talk past each other.
Before the chemical revolution, Joseph Priestley, a believer in 'phlogiston theory,' saw a substance being released from burning matter. He called it 'dephlogisticated air.' Antoine Lavoisier, looking at the same experiment, saw a substance being absorbed from the atmosphere and called it 'oxygen.' They weren't just interpreting the same event differently; they were seeing two fundamentally different phenomena.
Science Textbooks Are Propaganda for the Winners
Once a scientific revolution is complete, textbooks are rewritten to portray the new paradigm's victory as the inevitable, logical conclusion of a linear path of progress. They erase the crisis, the competing theories, and the messy, irrational nature of the actual shift.
Modern physics textbooks present Einstein's relativity as the clear, logical successor to Newton's mechanics. They omit the decades of crisis, the dead-end theories, and the profound resistance from established scientists who lived and died refusing to accept the new paradigm, making the revolution seem far more orderly than it actually was.
