Philosophy of Science
Muhammad Sajeer Bukhari
Chapter 08
Incommensurability
Incommensurability is a critical concept in the philosophy of science, introduced by Thomas Kuhn and Paul Feyerabend. It highlights the difficulties in comparing scientific theories that are fundamentally different. This essay will explore incommensurability, breaking it down into its essential components to provide a comprehensive understanding.
Understanding Incommensurability
Incommensurability refers to the idea that different scientific theories or paradigms cannot be directly compared using a common standard. When scientists transition from one paradigm to another, they are not merely improving their understanding but fundamentally altering their worldview.
Types of Incommensurability
Methodological Incommensurability
Different paradigms utilize distinct rules and methods to determine what is true or significant. There is no neutral ground to declare one paradigm superior to another. For example, Newton's theory of gravity replaced Descartes' because it made more accurate predictions, even though it initially lacked a complete explanation for gravity.
Observational Incommensurability
Our observations are influenced by the theories we believe in, meaning that what we see is shaped by what we think. Scientists' observations can be influenced by the theories they support, similar to how people interpret optical illusions differently based on prior knowledge.
Semantic Incommensurability
This involves the language and concepts used in different paradigms. Key terms in one scientific theory may mean something entirely different in another, making communication and comparison challenging. For instance, the term "space" in Newtonian mechanics differs fundamentally from its meaning in Einsteinian physics, where space and time merge into spacetime.
Challenges to Incommensurability
Methodological Incommensurability
Even though scientists agree on general criteria like accuracy and simplicity, these criteria are often too vague to resolve disagreements. Historical examples show that scientists prioritize different criteria at different times.
Observational Incommensurability
Some argue that not all observations are theory-dependent. Certain perceptions remain constant despite awareness of illusions, and scientific instruments aim to minimize personal biases, providing more objective observations.
Historical Counterexamples
Instances like the "Martian canals" demonstrate that basic observations can remain stable across different paradigms, suggesting that while theories influence interpretation, some observational facts are consistent.
Conceptual Incompatibility in Semantic Incommensurability
Semantic incommensurability also involves terminological incompatibility, where theories are conceptually incompatible due to differing lexical taxonomies. Understanding main terms requires understanding their theoretical principles, and meaning-variance arises when these principles change. This means the meaning of scientific terms changes if the theory changes or is replaced by another theory involving that term.
Achinstein's Challenge
Peter Achinstein argues against the necessity of full theory comprehension to understand terms and posits that some theoretical factors remain constant, allowing for comparison. Israel Scheffler’s distinction between sense and reference provides a way to navigate conceptual differences, though Mary Hesse and Michael Martin emphasize the importance of intensional properties and referents.
Relevant Conceptual Incompatibility
To address conceptual incompatibility, we must consider both sense and reference. Two theories are conceptually incompatible about a relevant term if they differ in both sense and reference. This approach allows for comparing theories by focusing on the types of phenomena they describe.
Phenomenon Types
Phenomena are experiences structured in specific ways, and phenomenon types are the conceptual spaces describing these experiences.
Subject Matter
Subject matter is a system of differences that allows for the comparison of theories focused on the same phenomenon type, even if they use different terms and concepts. For example, Newtonian mechanics and relativistic mechanics can be compared regarding motion despite their differing interpretations of "velocity."
Incommensurability, through relevant terminological incompatibility, provides a framework for comparing rival scientific theories. By focusing on phenomenon types and subject matter, we can understand scientific progression and the evolution of knowledge, maintaining the possibility of scientific realism and progress through sequences of incommensurable theories. This comprehensive approach reveals the intricate dynamics of scientific development and highlights the ongoing debate about how best to understand and compare scientific theories.