Scientific Revolutions and Incommensurability
When a scientific paradigm faces enough anomalies that it can no longer function, a Scientific Revolution occurs. This isn’t just an update to old ideas; it is a fundamental shift in how scientists see and interact with the world.
The Paradigm Shift
A paradigm shift is often compared to a “gestalt switch.” Just as an image can be seen as both a duck and a rabbit, but not both at once, a scientist switches from one way of seeing the world to another. Examples include:
- The shift from Ptolemaic (Earth-centered) to Copernican (Sun-centered) astronomy.
- The shift from Newtonian physics to Einsteinian relativity.
Incommensurability
Kuhn’s most controversial claim was the principle of Incommensurability. He argued that competing paradigms lack a “common measure” or objective vocabulary.
Because of this, you cannot simply say Paradigm B is “better” than Paradigm A based on pure data. Why?
- Conceptual Incommensurability: Words change meaning (e.g., “mass” in Newton’s world is constant, but in Einstein’s, it is variant).
- Observational Incommensurability: Data is interpreted through the lens of the paradigm itself.
- Methodological Incommensurability: The standards for what counts as a “good” explanation change.
Non-Linear Progress
Kuhn’s view implies that science does not move linearly toward “The Truth.” Instead, it is a sequence of different ways of looking at the world that are better at solving the puzzles prioritized by each community. While a new paradigm might solve the anomalies of the old one, it might also lose some of the problem-solving capabilities or insights of its predecessor.
The Conversion Process
Because paradigms are incommensurable, the transition from one to another is not purely logical. It involves a “conversion” similar to a religious experience. Younger scientists are often more likely to adopt the new paradigm, while older ones may never fully make the switch—a phenomenon Planck described by saying that science “advances one funeral at a time.”