Thomas Kuhn argues that science does not progress simply by accumulating facts or continuously falsifying theories. Instead, mature sciences alternate between periods of normal science and revolutionary paradigm shifts.
A paradigm is the shared framework of assumptions, concepts, methods, standards, and exemplary solutions accepted by a scientific community. During normal science, scientists accept this framework and solve “puzzles” within it rather than constantly questioning its foundations.
| Stage | What happens |
|---|---|
| Normal science | Scientists apply the dominant paradigm to explain observations and solve puzzles. |
| Anomalies | Results appear that the paradigm cannot explain satisfactorily. These are usually treated as research problems, not immediate refutations. |
| Crisis | Persistent or significant anomalies weaken confidence in the existing paradigm. Competing frameworks may emerge. |
| Scientific revolution | The scientific community replaces the established paradigm with a rival one. |
| New normal science | Scientists conduct research within the new paradigm until further anomalies accumulate. |
For example, the transition from Newtonian physics to Einstein’s relativity changed fundamental ideas about space, time, gravity, and acceptable scientific explanation. This was not merely an extra fact added to Newton’s framework; it reorganized the framework itself.
Kuhn describes rival paradigms as incommensurable because they may use different concepts, standards, and ways of interpreting evidence. There is no completely neutral standard by which every paradigm choice can be mechanically decided. However, this does not mean that choices are irrational: scientists may consider accuracy, consistency, scope, simplicity, and fruitfulness.
A common misconception is that Kuhn believed science makes no progress. He accepted progress in puzzle-solving power, but rejected the idea that science necessarily moves in a straightforward, cumulative path toward final objective truth.
Exam technique: For an “explain” question, define paradigm and present the sequence from normal science to revolution. For evaluation, contrast Kuhn with Popper’s falsificationism and assess whether incommensurability makes scientific change rational, relativistic, or partly dependent on scientific communities.
