Incommensurability - Definition and Overview

This article is about incommensurability in philosophy. For the mathematical meaning of (in)commensurable and (in)commensurability, see commensurable.

In the philosophy of science, incommensurability is the idea that it is possible to see the world in multiple ways, and that there is not always an impartial method for neutral communication between those views or for determining which view is true. Some philosophers, like Paul Feyerabend (1975), have been critical of the idea that incommensurability can be defined.

Kuhn's point of view

The idea that scientific paradigms are incommensurable was popularized by the philosopher Thomas Kuhn in his book The Structure of Scientific Revolutions (1962). He wrote that when paradigms change, the world itself changes with them (see esp. Chapter X of this book). According to Kuhn, the proponents of different scientific paradigms cannot make full contact with each other's point of view because they are, as a way of speaking, living in different worlds. Kuhn gave three reasons for this inability:

1. Proponents of competing paradigms have different ideas about the importance of solving various scientific problems, and about the standards that a solution should satisfy.
2. The vocabulary and problem-solving methods that the paradigms use can be different: the proponents of competing paradigms utilize a different conceptual network.
3. The proponents of different paradigms see the world in a different way because of their scientific training and prior experience in research.

In a postscript (1969) to the The Structure of Scientific Revolutions, Kuhn added that he thought that incommensurability was, at least in part, a consequence of the role of similarity sets in normal science. Competing paradigms group concepts in different ways, with different similarity relations. According to Kuhn, this causes fundamental problems in communication between proponents of different paradigms. It is difficult to change such categories in one's mind, because the groups have been learned by means of exemplars instead of definitions. This problem cannot be resolved by using a neutral language for communication, since the difference occurs prior to the application of language.

Feyerabend's point of view

The philosophy of Paul Feyerabend was also based on the idea of incommensurability to a large extent. Feyerabend argued that frameworks of thought, including scientific paradigms, can be incommensurable for three reasons. His list of reasons is similar to that of Kuhn:

1. The interpretation of observations is implicitly influenced by theoretical assumptions. It is therefore impossible to describe or evaluate observations independently of theory.
2. Paradigms often have different assumptions about which intellectual and operational scientific methods result in valid scientific knowledge.
3. Paradigms can be based on different assumptions regarding the structure of their domain, which makes it difficult to compare them in a meaningful way.

According to Feyerabend, the idea of incommensurability cannot be captured in formal logic, because it is a phenomenon outside of its domain.

References

• Feyerabend, Paul. (1975). Against Method: Outline of an Anarchistic Theory of Knowledge.
• Kuhn, Thomas. (1962). The structure of scientific revolutions.