New paradigms are incommensurable with previous ones
New paradigms cannot be understood by those who are in the old. The lexicon itself is no longer usable across paradigms, and debates between paradigms tend to be circular.
The normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before.[1]
Kuhn explains the meaning of the term:
The term incommensurability is borrowed from ancient Greek mathematics, where it specified the relationship between two quantities which possessed no common measure—no unit, that is, which each contained some integral number of times. The hypotenuse and side of an equilateral right triangle are the most famous example; the radius and circumference of a circle are another. Applied metaphorically to the relation between successive scientific theories, incommensurability meant no common lexicon, no set of terms with which all components of both theories could be fully and precisely stated.[2]
See also:
- Paradigm arguments are circular
- New paradigms are preceded by crisis
- Paradigm shifts reconstruct the field from new fundamentals
The Structure of Scientific Revolutions – Kuhn (1962), ch. 9. ↩︎
The Last Writings of Thomas S. Kuhn – Kuhn (2022), § “Lecture II: Portraying the Past.” Kuhn notes that the term untranslatability is a better word for incommensurability in reference to the relation between successive scientific theories. ↩︎