§5 Scientific Revolutions and Paradigm Shifts

If you ask most people how science progresses, they will describe a “brick-by-brick” model: scientists slowly and steadily add new facts to a growing pile of knowledge. However, the historian and philosopher of science Thomas Kuhn argued in his landmark book, The Structure of Scientific Revolutions, that science actually moves through “fits and starts”—long periods of stability followed by violent intellectual upheavals.

5.1 The Concept of a Paradigm

Central to Kuhn’s theory is the Paradigm. A paradigm is more than just a theory; it is an entire “worldview” or “map” that a scientific community uses to understand reality. It defines:

• What questions are worth asking.

• What methods are considered “scientific.”

• What counts as a “fact.”

5.2 The Life Cycle of Science

Kuhn argued that science moves through a predictable cycle of three distinct phases:

Phase 1: Normal Science

During this phase, scientists work within a stable paradigm. They aren’t trying to discover “new” things; they are “puzzle-solving.” They take the existing rules (like Newtonian Physics) and apply them to smaller and smaller details.

• The Key Feature: If an experiment fails during “Normal Science,” the scientist assumes they made a mistake, not the paradigm.

Phase 2: Crisis

Eventually, scientists encounter Anomalies—facts that flatly contradict the paradigm and cannot be explained away. At first, these are ignored. But as the “pile” of anomalies grows, the community loses confidence. This is a Crisis.

• Example: In the late 1800s, Newtonian physics could not explain the strange orbit of Mercury. This “anomaly” eventually led to a crisis in classical physics.

Phase 3: Revolution (The Paradigm Shift)

When a new paradigm is proposed that explains the old data plus the new anomalies, a Scientific Revolution occurs. This is not a gradual change; it is a “conversion experience.” Scientists begin to see the world differently.

• Example: The shift from the Geocentric (Earth-centered) model to the Heliocentric (Sun-centered) model was not just a change in math—it was a change in the entire human understanding of our place in the universe.

5.3 Incommensurability: Speaking Different Languages

One of Kuhn’s most controversial ideas is Incommensurability. He argued that when a paradigm shift happens, the old and new scientists are literally “living in different worlds.”

Because their definitions and methods have changed, they cannot fully understand each other. To a Reasonable Person, this is a reminder that even our most “objective” scientific facts are tied to the mental map we are currently using.

§5 Summary Table: The Anatomy of a Revolution

CHAPTER 11: Final Recap

Science is a powerful tool, but it is a human tool. It is judged by its Testability (§1), influenced by the Observer (§2), defined by its Falsifiability (§3), shaped by social Values (§4), and periodically overturned by Revolutions (§5). A Reasonable Person respects science not as an infallible source of absolute truth, but as the most rigorous, self-correcting method we have for navigating the unknown.