Philosophy Incommensurability

Philosophy of Science


In The Structure of Scientific Revolutions, Kuhn emphasizes incommensurability as necessary when dealing with discussion between believers in new versus traditional scientific paradigms. In this theory of incommensurability, believers of these competing paradigms view certain aspects of the world extremely differently and therefore are unable to accurately understand the other paradigm. Assuming that all competing scientific paradigms are incommensurable, it is impossible for traditional linear progress of paradigms to occur according to Kuhn, but evolutionary style progress in problem solving may still take place. In this short essay I will give a background on Kuhn’s paradigm incommensurability, and I will argue that this kind of incommensurability is a valid argument, and therefore scientific paradigms do not progress in the way that is commonly perceived.
Kuhn’s three-tiered argument for the incommensurability of paradigms lays the groundwork for his later argument against traditional linear progress. In the first part of his argument for incommensurability Kuhn claims “proponents of competing paradigms will often disagree about the list of problems that any candidate for paradigm must resolve. Their standards or their definitions of science are not the same” (Kuhn 148). By this Kuhn means that scientists, who believe in conflicting theories, can not fully see the other theory’s point of view because they can not reach a final agreement about what a theory must explain or include. Therefore important questions and ideas in one theory may be largely irrelevant to a competitor’s theory. For one example Kuhn uses Newtonian dynamics’ lack of explanation of particle attraction to illustrate its incommensurability with Aristotle’s theory of motion, which explains why particles are attracted to one another (Kuhn 148). Without agreement on what a theory must include it is obviously difficult to having a meaningful discourse about a particular scientific paradigm.

Secondly Kuhn asserts, “new paradigms… ordinarily incorporate much of the
vocabulary and apparatus, both conceptual and manipulative, that the traditional paradigm had previously employed. But they seldom employ these borrowed elements in quite the traditional way” (Kuhn 149). Essentially Kuhn is arguing that although competing paradigms may appear similar on the surface because of common terms and equipment, these tools are used in very radically different ways. So much so that members of different paradigms may appear to be discussing the same topic but actually may be talking about two different things. Kuhn illustrates this incommensurability through the conflict between Einstein and Newton’s differing definitions space (Kuhn 149). Because the two paradigms define space differently it is impossible to accurately compare the two. This subtlety of definition is something that one in the non-scientific world may easily overlook, but Kuhn does an excellent job in recognizing and explaining. If competing models cannot agree on something so basic as language it is difficult to make a comparison and choose the more valid theory.
Thirdly Kuhn states “proponents of competing paradigms practice their trades in different worlds” (Kuhn 150). This argument seems to be the most reiterated and basic justification of incommensurability throughout the essay and rightfully so. Kuhn believes that scientists view their paradigms as different worlds. Although they may appear to be looking at the same item from the same angle, the competitors are interpreting what they see totally differently. The classic gestalt switch example of the rabbit and duck exemplifies this contrast in views (Kuhn 114). It easy to see how difficult it would be for one scientist to understand what the other scientist sees if they are working in different paradigms where one sees a duck and the other, a rabbit. Unless there is complete conversion to ducks or rabbits, it is impossible for a scientist to totally see the other side while still envisioning his own. Therefore any comparison is at most only partial because this incommensurability of paradigms prevents anything but a quite limited exchange from occurring.

This multifaceted argument for incommensurability is strong, and if it is accurate then there cannot be progress from one paradigm to another in a linear fashion towards a specific goal of truth. Hempel would disagree with this argument because in his view all science progresses towards the truth as knowledge, in the form of empirical evidence, accumulates (Hempel 1-2). This accumulation does not allow for dismissal of what was considered knowledge in the past, and therefore it inaccurately assumes that all knowledge is collected in a search for a unique truth. But there is not “a permanent fixed scientific truth” that scientists are progressing straight towards, and instead progress is better defined as an “evolutionary process” (Kuhn 173). Through this evolutionary process, a diverse array of paradigms may be utilized to solve the puzzles of nature at different points in history using the available knowledge of the era. Therefore the current paradigm will in theory be the best-known problem solver given the present knowledge available. This survival of fittest paradigm by measure of its usefulness is quite logical, and seems much more rational than assuming that scientific progress is constantly advancing towards a goal of a fixed truth. After all, truths may vary according to knowledge available at any given time. What we view as a scientific truth in 2003 may not be considered one at all in 2103. It is wrong to construct a meta-narrative of science, which claims to be searching for the truth but alters its own history to make it’s progress appear more linear. This is a history based on lies.

Clearly there are times when the scientific community has done this, and it has discounted what was considered past scientific progress and truths in order to make it seem as if the current paradigm developed as part of a linear search for the truth (Kuhn 138). But truths are flexible, and new truths emerge with new paradigms. As Kuhn mentions, there are various examples, particularly of science textbooks using history out of context to legitimate the alleged linear search for the truth, which has supposedly led right up to the most recent theory (Kuhn 137-140). This misleading focus on past contributions to the current paradigm, regardless of context, casts the largest shadow of doubt upon Hempel’s cumulative view of science and favors Kuhn’s theory of incommensurability, which allows for rejection of past progress.

Incommensurability of competing paradigms is hard to deny and clearly the generic view of linear progress is skewed. Therefore Kuhn’s argument appears quite sound, but even Kuhn admits that this incommensurability of competing paradigms is “inevitably only partial” (Kuhn 198). Some of the meanings discussed between the two competing paradigms are the same but some are different. But it is these different interpretations that lead to the general sense of incommensurability between competing paradigms of scientific thought. Thus recognizing this incommensurability is necessary when dealing with communication between believers in new versus traditional scientific paradigms.

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