Chapter IX of Kuhn, Structure of scientific revolutions (p. 53 - 56)
Kuhn argues that successive paradigms in a scientific-revolution are logically incompatible.
- new theories / paradigm emerge to resolve anomalies faced by the current normal-science
- For a new theory to successfully resolve these anomalies, it must make different predictions from the old theory in exactly those problematic areas
- Therefore, If the new theory makes different predictions than the old theory (in some domain), the two theories cannot both be true = they are logically incompatible (p. 97)
This is also due to the non cumulative nature of paradigm shifts.
[A paradigm shift]is a reconstruction of the field from new fundamentals, a reconstruction that changes some of the field’s most elementary theoretical generalizations as well as many of its paradigm methods and applications. During the transition period there will be a large but never complete overlap between the problems that can be solved by the old and by the new paradigm. (p.84)
Types of incompatibility =
- predictive incompatibility = make different empirical predictions about observable phenomena
- conceptual incompatibility = define differently what entities posit as real and how they conceptualize nature
- methodological incompatibility = differ in what counts as legitimate scientific questions, what counts as an acceptable solution, what counts as relevant evidence
If successive paradigms were compatible, we could simply add new knowledge to old, which is the traditional view of scientific progress. Instead, progress is shown to be a non-cumulative view by Kuhn (Role-of-history-in-Kuhn-account-of-science).
Since paradigms are a source of methods, problem-field, and standards of solution accepted by the scientific community at any given time, the reception of a new paradigm often necessitates a redefinition of the corresponding science (p. 103). This makes paradigms not just incompatible but also leads to incommensurability
Paradigm choice cannot be purely logic
When two paradigms are incompatible, the natural assumption is to use logic and evidence to prove which one is correct, but Kuhn argues that this is impossible because of a circularity problem.
Judging the new paradigm with the standards of the old paradigm “begs the question”, because it assumes the old paradigm’s standards are correct standards when that is the thing exactly in dispute during a scientific-revolution. Judging the old paradigm with the standards of the new paradigm makes the same type of assumption (that one standard is correct).
The last option would be to find a paradigm-independent objective criteria that both sides would accept. According to Kuhn though, all standards are paradigm-dependent. Even criteria like “empirical accuracy,” “simplicity,” or “explanatory power” mean different things in different paradigms and are weighted differently.
There is hence no algorithm for choosing between paradigms, and logic cannot settle the matter. Instead, Kuhn says paradigm shifts involve persuasion and conversion. This can come as a radical claim, as it implies that science is subjective and resembles politics or religion.
question: how do we choose between paradigms then?