This blog post delves deeply into Thomas Samuel Kuhn’s paradigm theory and its philosophical significance, which challenged the belief that science represents absolute truth.
Since the modern era, science has earned humanity’s boundless trust. The material prosperity promised by science and technology, coupled with the epistemological justification that science represents certain truth, further solidified this faith. This is because the advancement of science and technology and the philosophical clarification of science’s essence are intrinsically linked. However, as we moved beyond the mid-20th century, new philosophical explanations of science’s essence emerged, enabling us to move beyond blind trust in science and technology and engage in critical reflection. As the belief that science constitutes certain knowledge came under challenge, the social, historical, and political nature of science and technology began to emerge. This shift in the conception of science altered public awareness of science, and this change in public awareness influenced policy decisions, ultimately transforming culture as a whole.
The philosopher who decisively transformed the conception of science in the 20th century was Thomas Samuel Kuhn (1922-1996). He dismantled the prevailing consensus on the nature of science that had existed until the mid-20th century and introduced a new way of thinking. In The Structure of Scientific Revolutions, published in 1962, he shook the very foundation of the traditional belief that science is an activity progressing toward unchanging truth. He noted that science resembles other human activities like art or religion, and argued through historical examples that scientific development has proceeded in an irrational manner. How could science, considered rational, develop irrationally? First, let’s examine in detail his claim that brought a revolutionary change in the perspective on science.
According to Thomas Samuel Kuhn, the structure of scientific development consists of distinct stages. A scientific community accepting a single paradigm undergoes the following changes:
1. They perform normal science, solidifying the paradigm.
2. During the practice of normal science, problems that cannot be solved by the existing paradigm accumulate, leading to a crisis of the paradigm.
3. Subsequently, a paradigm entirely different from the old one emerges, ushering in a stage of scientific revolution where two or more paradigms compete.
4. When the new paradigm supplants the old and is accepted by the scientific community, a new phase of normal science begins.
Thomas Samuel Kuhn argued that historically, irrational factors—such as aesthetic simplicity or beauty, or a scientist’s reputation or personal beliefs—primarily drove the scientific community’s abandonment of old paradigms and adoption of new ones. He explained this through the concept of incommensurability between the two paradigms. Incommensurability means that because the problems considered important and the methods of solving them differ between the old and new paradigms, it is impossible to say which is superior. In other words, the two paradigms cannot be compared or evaluated using the same criteria. Therefore, Thomas Samuel Kuhn argues that scientists abandoning an old paradigm and adopting a new one is primarily determined not by rational criteria, but by the aforementioned irrational factors. Ultimately, paradigm shifts and scientific progress occur through irrational factors, similar to religious conversion.
As Thomas Samuel Kuhn argues, irrational factors can significantly influence individual scientists’ process of abandoning past paradigms and choosing new ones. This claim appears difficult to refute, as it is grounded in historical examples of scientific development. However, when considering scientific progress from the long-term perspective of the entire scientific community fully embracing a paradigm and its establishment, I believe scientific advancement is driven more by rational factors than irrational ones. Before discussing this, let us first examine the process by which the heliocentric theory was accepted as a new paradigm within the scientific community.
We commonly know that Nicolaus Copernicus (1473-1543) was the first to propose the heliocentric theory. However, over 1,700 years before Copernicus presented his theory, the ancient Greek astronomer Aristarchus (310 BC–230 BC) had already argued that the Sun was the center of the universe and that the Earth and planets revolved around it. However, ancient Greece lacked the social context to accept the heliocentric theory, and insufficient astronomical evidence to support it meant his theory went largely unnoticed. Over time, humanity accumulated celestial observation data and astronomical knowledge. Building on this, in 1543, Copernicus systematized the heliocentric theory in his book On the Revolutions of the Celestial Spheres. However, his theory also had limitations, requiring the addition of epicycles to explain the motion of the celestial bodies, and thus was not accepted in his own time.
At this time, the German scientist Johannes Kepler (1571-1630), deeply impressed by Copernicus’s heliocentric theory, began his astronomical research. Subsequently, in 1609, Kepler presented a heliocentric theory that complemented Copernicus’s work. Although there was some opposition, its theoretical completeness led to a significant increase in supporters.
The belief that God and humanity were the center of the universe was dominant when Aristarchus, Copernicus, and Kepler advocated the heliocentric theory. This belief also greatly influenced whether the scientific community accepted the paradigm. While the heliocentric theories of Aristarchus and Copernicus went largely unnoticed, Kepler’s heliocentric theory was accepted due to the vast accumulated astronomical knowledge of the time and the theoretical completeness of Kepler’s work. There are records suggesting Kepler was influenced by solar worship ideas during his shift to the heliocentric view, but this appears to apply only to a small number of pioneering scientists. The majority of scientists choose a new paradigm based on its rational explanations and the limitations of the old paradigm. Since paradigm shifts occur through the rational judgment of the scientific community’s majority, the long-term development of science can be seen as driven by rational factors, contrary to Thomas Samuel Kuhn’s claims.
For this argument to hold, a rational criterion must exist to compare the old paradigm with the new one. Thomas Samuel Kuhn argued that the two paradigms are incommensurable, meaning there is no rational basis for comparison. However, consider the goal of science. Science is the activity of gaining knowledge about natural phenomena through experimentation and verification, and then systematizing this knowledge. Paradigms emerge within the broader framework of science, and while the direction of normal science may differ between paradigms, they share the goal of rationally explaining natural phenomena. Two paradigms can be compared based on which one provides a more rational explanation of natural phenomena and presents a more suitable model. Therefore, the scientific community can rationally select paradigms, and scientific progress can be said to occur rationally based on accumulated knowledge and theory.
Thomas Samuel Kuhn, in The Structure of Scientific Revolutions, interpreted scientific progress not as an accumulation toward truth but as occurring through periodic revolutions. He argued that an incomparability exists between the old and new science before and after a revolution, and that scientists choose paradigms not based on rational evidence but through irrational factors akin to religious conversion. Kuhn’s claim holds significant meaning in that it shook the belief in science as absolute truth. However, considering the goals of science, comparability exists between the two paradigms, and from the long-term perspective of the scientific community, scientific progress can still be seen as occurring rationally. I believe Thomas Samuel Kuhn’s claim that scientific progress occurs irrationally is extreme. Nevertheless, Kuhn’s argument holds significant value in that it prompted a reexamination of the blind faith in science as absolute truth.
