This blog post explores whether science progresses or merely shifts, focusing on Thomas Kuhn’s concept of incommensurability.
Thomas Kuhn’s ‘The Structure of Scientific Revolutions’, which introduced his paradigm thesis, was published in 1962 and immediately sparked the ‘Kuhnian Revolution’. Thomas Kuhn’s theory of scientific development and change, condensed into the paradigm concept, has established itself as one of the most influential ideas in modern thought, gaining widespread recognition across philosophy of science, natural sciences, and social sciences. In this blog post, I will delve deeper into the concept of ‘incommensurability under the same standard’—the idea that different paradigms are mutually incomparable—from among Thomas Kuhn’s paradigm-related arguments. Simultaneously, I aim to identify the limitations inherent in Thomas Kuhn’s paradigm and ultimately consider whether the paradigm is a concept capable of progress.
Before delving into a substantive discussion of paradigms, we must first examine what Thomas Kuhn’s theory and paradigm actually are. The core concept of this book, the paradigm, originally signifies a theoretical framework or set of concepts that governs the actions and thinking of people in a given era. However, Thomas Kuhn used the term paradigm to refer to concepts, laws, values, knowledge, and habits shared by the entire scientific community. Thomas Kuhn believed that change and development in science are discontinuous or revolutionary, not development-by-accumulation. According to Kuhn, “A scientific revolution occurs when normal science collapses under the pressure of frequent and serious anomalous phenomena, and the result is a new normal science.”
Thomas Kuhn’s view directly contradicted the prevailing theory of the early 1900s, ‘logical positivism’ or ‘logical empiricism’. According to the logical empiricist view, which explains the development of science based on theory-neutral observation and logical inference, scientific knowledge grows continuously and cumulatively throughout history. In contrast, Thomas Kuhn explains the change and development of science using the concepts of ‘normal science’ and ‘scientific revolution’. Unlike the prevailing logical empiricist view, Thomas Kuhn believed scientific change occurs discontinuously and non-accumulatively. As Kuhn explained, if scientific change is revolutionary and discontinuous, a stable period preceding the revolution is necessary. Thomas Kuhn defined this period as the era of normal science. When normal science faces a crisis due to new anomalous discoveries and suffers significant failure, the existing paradigm is replaced by a new paradigm, termed a scientific revolution.
According to Thomas Kuhn’s logic above, during the process of replacing the existing paradigm, the new paradigm appears to be more advanced and moving in the correct direction. Examples include the shift from Ptolemy’s geocentric worldview to Copernicus’s heliocentric astronomy, the birth of Lavoisier’s oxygen theory of combustion, and the emergence of relativity theory from the crisis of classical physics in the late 19th century. Observing these examples, I thought the emergence of a new paradigm seemed to resolve the problems inherent in the old one. So, can we say the new paradigm is more advanced than the old? Thomas Kuhn answers this question as follows:
“Competing paradigms are incommensurable, meaning they cannot be compared using the same logical criteria. Accepting one paradigm means believing in its entire system, including its concepts, laws, and assumptions; thus, its parts cannot be separated for comparison or evaluation.”
In summary, Thomas Kuhn argues that a new paradigm exists on a baseline that is incommensurable with the existing paradigm, and therefore, the new paradigm cannot be deemed more advanced. He explains that paradigm shifts are like gestalt switches or religious conversions—a matter of choice, not one where superiority can be determined.
According to Thomas Kuhn, the development of each paradigm is only possible within the world to which that paradigm belongs; the concept of progress or advancement to a new paradigm cannot exist. Since each paradigm employs a different vocabulary system, comparison itself is fundamentally precluded. As explained above, Thomas Kuhn’s view has a logically plausible aspect. However, I propose the following critique. First, the most significant problem is that supporting Thomas Kuhn’s view makes one prone to falling into relativism. In other words, if competing paradigms are inherently logically incompatible, making mutual comparison impossible, then all actions undertaken under the name of science—which relies on ‘comparison with existing theories’ as its driving force for growth—become meaningless. If the existing dominant paradigm and a new paradigm cannot be compared, one must question where the incentive for a new paradigm to emerge actually originates. Furthermore, if, like Thomas Kuhn, one interprets all phenomena through the lens of paradigms, then systematic analysis of natural phenomena and the positivist approach based on direct experience and observation, as in traditional logical positivism, become meaningless. Science can then only exist as a relative, subjective quality.
I believe paradigms gradually progress through the process of discarding old paradigms and transitioning to new ones. To illustrate simply, consider comparing Copernicus’s heliocentric theory with Ptolemy’s geocentric theory. The existing geocentric worldview, Ptolemy’s geocentric model, was refuted by the emergence of Kepler’s laws and Copernicus’s heliocentric model, rendering it incapable of explaining planetary motion. In other words, the advent of a new paradigm led to the abandonment of the old one. Thomas Kuhn uses this case in his book The Structure of Scientific Revolutions to explain the concept of paradigms to readers. However, I do not view this merely as the emergence of a new paradigm that is different from and incommensurable with the old one (according to Kuhn’s view). The existing paradigm, Ptolemy’s geocentric model, could not adequately explain the phases of Venus or the parallax of stars at the time. Ptolemy’s geocentric model, which posited that all planetary motion occurred around the Earth, was ‘falsified’ by the phases of Venus and the parallax of stars, proving it incorrect. Consequently, it could no longer hold status as a theory of planetary motion. Of course, according to Thomas Kuhn’s view, even in such a case, the two theories are independent and relative, employing different linguistic systems and value systems, making them incomparable. However, the actual physical phenomenon exists absolutely as one, and to claim that systems describing it cannot be compared simply because they differ borders on nihilism that hinders scientific progress. Clearly, Copernicus’s heliocentric theory has less potential for ‘falsification’ than Ptolemy’s geocentric theory and can be said to be closer to ‘truth’. Thus, unlike Thomas Kuhn’s view, I do not believe that paradigms are inherently incomparable due to incommensurability. Clearly, connections must exist between each paradigm. Through falsifiability, we can determine their relative merits and distinguish more advanced paradigms.
This difference ultimately stems not from a question of right or wrong, but from a fundamental divergence in philosophical worldviews. This author’s perspective aligns to some extent with that of Karl Popper, the Austrian philosopher of science. According to a paper by Hong Chang-seong discussing Popper’s arguments, the following passage appears:
“Karl Popper states he himself adheres to commonsense realism. He believes in the existence of an objective world with almost naive simplicity. For him, refuting evidence against a theory possesses the powerful force to instantly disprove that theory as an objectively true, existing fact.”
According to this view, Karl Popper perceives science as absolute truth and believes in the existence of an objective world. This differs from Thomas Kuhn’s concept of a relative paradigm worldview. The author also supports his theory of falsifiability and the absoluteness of science.
Contrary to the author’s view, Thomas Kuhn ultimately argues that the idea scientists can approach truth through paradigm shifts is meaningless. He cites Darwin’s theory of evolution as an example. He points out that while famous evolutionary theories before Darwin were all goal-oriented processes, Darwin’s proposal that life evolved without any goal, starting from a primitive beginning, rendered such thinking contradictory. Thomas Kuhn asks himself, “What meaning can evolution, development, or progress have without a specific goal?” However, Thomas Kuhn’s stance is incorrect. It is an extremely nihilistic position, arising from his tendency to interpret all natural phenomena and scientific activities within the framework of paradigms. While there may be differences between the ‘truth’ Thomas Kuhn envisions and the ‘truth’ I envision, evolution undeniably exists as a natural phenomenon. Direct experience and observation of this phenomenon allow us to describe the evolutionary processes of living organisms with greater factual accuracy. For instance, the discovery of fossils and the phenomenon of finding missing links between fossils exemplify this well. If we consider gradually approaching these absolute facts as truth, then we can say we are steadily drawing nearer to truth. In other words, it is a matter of how we perceive the approach towards ‘truth’. Furthermore, the absence of purpose in evolution does not render everything related to evolution meaningless. Through continuous exploration, there remains the potential to propose directions more beneficial to humanity in environmental and economic terms, and this too could be termed social scientific progress.
Thus far, we have examined Thomas Kuhn’s concept of paradigms and its core element, the incommensurability of different standards. Centering on this, we have raised critiques regarding the blind spots inherent in Thomas Kuhn’s arguments. We have directly challenged Thomas Kuhn’s relativistic stance by introducing the author’s logic and Karl Popper’s concepts. It is said that Thomas Kuhn’s paradigm still enjoys the support of the overwhelming majority. However, paradoxically, since there is no absolute truth from Thomas Kuhn’s perspective, one might consider whether criticism itself is not possible.
