This blog post examines whether science progresses through accumulation or if paradigm shifts are the core driving force, offering an in-depth analysis of the actual mechanisms of scientific development based on the perspectives of Kuhn and Popper.
The debate over how scientific progress occurs continues unabated today. While perspectives on scientific advancement vary, the positions presented by Thomas Kuhn and Karl Popper form two representative axes of discussion. Popper viewed science as developing through the repeated process of constant attempts at falsification and defense against such attempts, premised on falsifiability. His argument was that if a specific theory fails to defend against proposed falsifications, it must collapse, and science progresses gradually through the accumulation of such continuous falsification and defense. Conversely, Kuhn explained scientific development as a process of replacing one revolutionary paradigm with another. However, Kuhn also acknowledged, through his concept of normal science, that the process of falsification and defense emphasized by Popper is indispensable throughout the entire scientific activity. Thus, while the discussions of these two scholars share similar points, their emphases differ. Both theories offer profound insights into scientific development, yet they still contain unfilled gaps. Various attempts to supplement these gaps have been made within modern philosophy of science. Nevertheless, fully harmonizing and unifying the positions presented by Kuhn and Popper remains a very difficult task. Moreover, there is no single correct answer regarding how science develops.
At this point, the question arises: why should we discuss the mode of scientific development and study the philosophy of science? Philosophy of science is the discipline that analyzes and reflects on scientific achievements to define scientific concepts, clarify scientific premises, and explore methodology. In other words, it aims to provide direction and a methodological foundation for scientists engaged in scientific activity. Therefore, I believe that for philosophy of science to be of practical help to scientists, arguments approached from the scientists’ perspective are necessary. For this reason, I propose reinterpreting paradigms based on scientists’ psychological states rather than categorizing them solely by outcomes or results. I support Kuhn’s paradigm theory regarding how science develops, viewing scientific progress as fundamentally driven by paradigm shifts, as indicated in the title. Below, I will present my rationale and interpretation regarding Kuhn’s paradigm theory and the role scientists’ psychological states play in the formation and transformation of paradigms.
Reviewing the history of scientific change, it is clear that theories have evolved through the work of various scientists, including Aristotle, Newton, and Einstein. Phenomena unexplained by Aristotle’s physics became explainable through Newtonian mechanics, and domains beyond Newtonian mechanics were resolved by Einstein’s theory of relativity. Within this sequential process, logical positivists and falsificationists concluded that science develops cumulatively. However, Kuhn presents a different perspective. He did not view Aristotle’s entire physics as flawed simply because it could not explain certain aspects. While Aristotle’s explanation that all matter possesses an inherent home may seem inadequate from today’s perspective, from the standpoint of his time, their worldview formed a logically coherent system.
The transition from Newton to Einstein provides a more direct illustration for understanding Kuhn’s perspective. Newtonian mechanics, a system describing motion using force, mass, and acceleration, was trusted across nearly all domains for a long period. However, problems emerged when speeds approached the speed of light, rendering Newtonian mechanics invalid. Relativity theory emerged as an alternative solution. Strictly speaking, the theory of relativity concludes that Newtonian mechanics is incorrect, yet simultaneously, Newtonian mechanics remains valid at low speeds and on macroscopic scales. Furthermore, Newtonian mechanics is scarcely used in the realm of quantum mechanics. Through these examples, Kuhn argues that science does not progress merely by accumulating falsifications, but rather changes through a process of fundamentally replacing existing worldviews—that is, paradigm shifts. Kuhn termed the theoretical and conceptual losses arising from the previous worldview as ‘losses’. After such a period, the stage of normal science arrives. During the normal science phase, scientists strive to refine the established paradigm by aligning theory with observation and expanding its explanatory power to encompass more phenomena. In this stage, there is a strong tendency to solve problems within the existing paradigm rather than pursue new theories; difficult problems may be addressed by introducing temporary hypotheses or temporarily ignoring them. As these difficult problems accumulate, space opens for a new paradigm to emerge, and Kuhn explained that this repetition is the driving force of scientific progress.
According to Kuhn’s perspective, science is an activity operating on the basis of paradigms, and a certain dogmatic attitude is necessary during the normal science phase. This concept of the paradigm critically responds to the emphasis placed by positivists on empirical objectivity and by falsificationists on the concepts of falsifiability, rationality, and truth. To accurately understand how paradigms operate, I believe it is necessary to first examine the concept of the ‘time’ during which a paradigm persists. Paradigms do not change at regular intervals; rather, the period during which a paradigm is maintained is the time from recognizing the limitations of the existing paradigm until a new system emerges to replace it. This period can be short or extremely long. For instance, the transition from Newtonian mechanics to quantum mechanics took a considerable amount of time. I view this period of normal science as sufficient time to overcome the ‘losses’ Kuhn described and establish a new paradigm. I judge that the new paradigm is an expanded system that includes the explanatory power of the existing paradigm while transcending its limitations. That is, problems solved by the old paradigm can also be solved by the new one, and additionally, the new paradigm addresses problems the old one could not solve. Therefore, supporting Kuhn’s position should not be misunderstood as completely discarding existing theories and starting ‘from scratch’ with an entirely new system. Nor should paradigm shifts be understood as repeating rapidly at short intervals.
Now, I wish to explain my new interpretation: the relationship between paradigms and the psychological state of scientists. The paradigms described by Kuhn are fundamentally distinguished as established theoretical systems. As mentioned earlier, representative examples include the paradigm dominated by Aristotelian physics, the paradigm centered on Newtonian mechanics, and the paradigm centered on quantum mechanics. While it is clear that paradigms play a crucial role in scientific progress, both Popper’s process of falsification and defense, and Kuhn’s dogmatic attitude within normal science, influence scientists’ ability to propose or accept new paradigms. However, I contend that the moment of paradigm shift is particularly critical for science to overcome existing limitations and advance to a new stage, and that the psychological changes among scientists at this juncture play a decisive role.
Science is ultimately an activity performed by human scientists, and humans inherently possess biases, preconceptions, and herd mentality. This forms the psychological backdrop where scientists operating within a specific era’s paradigm develop strong convictions about that paradigm. Witnessing other contemporary scientists trusting the same paradigm further reinforces this conviction. I believe this very point exerts a profound influence on paradigm shifts. For instance, even if a scientist points out the limitations of the existing paradigm and proposes a new framework, it is questionable whether scientists who firmly trust the existing paradigm and whose beliefs are reinforced by herd mentality can readily accept it. I believe this is not the case. Rather, the scientist proposing the new paradigm is likely to be treated as an eccentric or rejected, and his claims may be judged irrational by applying the criteria of the existing paradigm.
Real-world examples support this psychology. Copernicus, who advocated the heliocentric theory, experienced punishment and exclusion. When Rutherford presented an atomic model similar to the modern quantum model, many scientists at the presentation criticized it, arguing that Rutherford’s theory would collapse immediately based on Newton’s law of conservation of energy. Furthermore, suppose the theory of relativity is wrong. If a student were to argue to a professor that the theory of relativity is flawed, the professor would likely find it difficult to accept this claim immediately. Similarly, no matter how logical or rational a new paradigm may be, it is difficult to accept until scientists acknowledge the limitations of the existing paradigm. For a paradigm shift to occur, scientists must reach a psychological state where they recognize the problems within the existing system and yearn for a new direction. Therefore, I believe that defining the paradigm based on the point of psychological change among scientists is precisely the stage where scientists begin to research a new paradigm and become prepared to seriously accept it. This approach, interpreting scientific development from a human-centered perspective, possesses realistic explanatory power.
If we define paradigms based on scientists’ psychological states, solutions to several problems become apparent. When a specific group of scientists accepts a single paradigm through mutual subjective agreement and approval, that paradigm may appear to become the new standard. I partially agree with this point. However, a significant potential error exists here: if agreement and evaluation occur only within a specific group, the process of logical verification may not be sufficiently thorough. The most crucial principle in science is logical validity. Any theory or paradigm must be developed and evaluated based on logic. Therefore, the process of evaluating paradigms should not be confined to a specific region or school of thought, but should be conducted by the global scientific community as much as possible. Only then can logical rigor be sufficiently ensured, allowing a new paradigm to become established.
Some may criticize that classifying paradigms based on scientists’ psychological states is overly subjective, and that it remains ambiguous exactly which scientists are being considered and at what specific point in time. However, the core point the author wishes to emphasize is the very existence of paradigm shifts. Describing the moment when a scientific revolution occurs from the perspective of changes in human psychology provides a more realistic and relatable explanation than the conventional achievement-centered approach. Rather than viewing paradigms as changing abruptly at discontinuous moments, my perspective is that the transition occurs continuously and gradually as the proportion of scientists accepting the new paradigm steadily increases. Therefore, it is difficult to designate any single point in time as ‘the moment the paradigm shifted’. This interpretation naturally aligns with the position stated in the introduction: philosophy of science should be viewed from the perspective of scientists to provide them with practical assistance.
Thus far, we have examined Kuhn’s paradigm theory and, based on this, argued for the author’s scientist-psychology-based paradigm interpretation. Just as Kuhn acknowledged the dogmatic nature of paradigms, I do not entirely dismiss the importance of positivism or falsificationism. However, I wish to emphasize that the actual driving force behind scientific progress lies in the broader sense of paradigms and their shifts as Kuhn described, and that these shifts materialize through scientists’ psychological and cognitive transformations. In fields like science or mathematics, challenging established theories is no easy feat. Similarly, in other disciplines, arguments overturning long-established methods or perspectives are not readily accepted. For this reason, a paradigm shift should be understood not as the point where existing theories are completely discarded and rewritten, but rather as the psychological turning point when scientists begin to question established theories and seek new directions.
If we understand paradigms based on scientists’ psychology, researchers will encounter colleagues sharing similar concerns during their work, develop their logic, and view others’ research with a more open perspective than before. This will provide substantial help to scientific progress, and I believe this is a far greater advantage than a results-oriented approach. As long as scientists exist in this world and perfect theories do not, paradigms will inevitably exist. The moment of paradigm shift becomes a crucial indicator that science is progressing in the right direction. Therefore, moving beyond viewing scientific development solely through the lens of theory or achievement, and instead understanding it from the perspective of scientists’ psychological shifts, would offer a more realistic and relatable philosophical explanation of science for modern scientists.
