In this blog post, I will examine the core elements of the theory of scientific revolutions presented in Thomas Kuhn’s ‘The Structure of Scientific Revolutions’, and explore the limitations of that theory as well as areas where it could be improved.
Thomas Kuhn’s ‘The Structure of Scientific Revolutions’ is a work that brought about a major shift in the prevailing view at the time, which held that scientific progress was cumulative. He argued that science does not develop simply by steadily accumulating knowledge, but rather through revolutionary shifts. Once a paradigm is established, normal science develops within it; however, a crisis arises when anomalies that are difficult to explain using the existing paradigm accumulate beyond a certain threshold. Subsequently, a new paradigm emerges to replace the old one, thereby triggering a scientific revolution. While the process of scientific revolution proposed by Thomas Kuhn is certainly persuasive, I believe there are certain limitations to applying this theory to all scientific fields. In this paper, I aim to analyze the limitations of Thomas Kuhn’s theory and discuss ways to supplement it.
Before delving into the discussion, let’s examine the structure of a scientific revolution in a bit more detail. First, the scientific community adopts a single paradigm and conducts normal science within it. Here, a paradigm refers to the theoretical framework and research methods shared by the research community, which are recognized as superior to existing competing theories. It also serves to identify problems to be solved and research directions. Normal science is the process of solving problems within this paradigm. However, as research progresses, anomalies emerge that are difficult to explain using the existing paradigm, and if these anomalies continue to increase, they develop into a crisis. Amid such a crisis, a new paradigm emerges to replace the existing one, and this process is precisely what constitutes a scientific revolution. Kuhn explained that this change is not a process of simply accumulating prior knowledge, but rather a non-accumulative process that replaces the existing paradigm.
As representative examples supporting this claim, Kuhn cited Newton’s ‘Principia’, the development of electrical theory, Lavoisier’s theory of oxygen combustion, and Einstein’s theory of relativity. Newton’s ‘Principia’ led a scientific revolution by restructuring the existing system of mechanics around new concepts such as force, mass, and universal gravitation. Furthermore, while no unified paradigm existed in early research on electricity, the work of Benjamin Franklin and other researchers led to the formation of a common theoretical framework for electricity, gradually consolidating the various existing theories. Lavoisier proposed the theory of oxygen combustion, replacing the phlogiston theory, while Einstein, through his theory of relativity, explained phenomena that were difficult to account for using Newtonian mechanics alone from a new perspective. These examples clearly illustrate the typical characteristics of a scientific revolution as described by Kuhn. How, then, can we explain the following example?
Let’s examine the Modern Synthesis in evolutionary biology. The Modern Synthesis is a theoretical framework centered on Darwin’s theory of natural selection, integrating it with the then-developing field of population genetics and various research findings. Although modern evolutionary theory continues to expand with advancements in molecular biology, developmental biology, and evolutionary developmental biology (Evo-Devo), the Modern Synthesis remains a crucial foundation of modern evolutionary biology. Looking at this example, since it developed by integrating various existing theories and research findings, it is difficult to view it as a situation where the existing paradigm was completely discarded and there was a discontinuous shift to a new paradigm.
Kuhn argued that incommensurability arises when a new paradigm emerges. Incommensurability is explained in three main dimensions. First, when a paradigm changes, the criteria for judgment change. Second, the meanings of concepts and terms change. Third, the very way of viewing the same phenomena changes. However, when comparing the Modern Synthesis of Evolution with the various evolutionary theories that preceded it, it is difficult to argue that the meanings of concepts have completely changed, nor have the observed phenomena themselves changed. Rather, it is strongly characterized by the integration and supplementation of existing research findings.
Furthermore, unlike cases such as the theory of relativity or Newtonian mechanics—where a single groundbreaking theory replaced the existing paradigm—the modern evolutionary synthesis was formed by integrating the accumulated research achievements of numerous scholars. This demonstrates that while Kuhn’s theory effectively explains large-scale paradigm shifts, it fails to adequately account for the development of theories that emerge through the gradual combination of various research findings. This issue has long been a subject of ongoing debate in the field of biology, and some argue that a wider range of perspectives is needed to explain the entire history of biology.
We can also examine examples from mathematics. Mathematics is a discipline based on deductive logic. New theories develop on the basis of previous ones, and once a theorem has been rigorously proven, it generally remains valid thereafter. Of course, changes in axiomatic systems and the emergence of new fields do occur in mathematics as well, but these differ in nature from the paradigm shifts described in the natural sciences. Therefore, mathematics as a whole exhibits a pattern of development characterized by strong continuity and accumulation, and these characteristics are somewhat at odds with the model of scientific revolutions described by Kuhn.
The second limitation is that the process by which a new paradigm replaces an existing one is not necessarily radical. Although Kuhn explains that scientific revolutions occur relatively abruptly, there are numerous examples in the actual history of science where it took a long time for new theories to gain widespread acceptance. Copernicus’s heliocentric theory also took a considerable amount of time to completely replace Ptolemy’s geocentric theory, and Newton’s theory likewise gradually established itself as the new standard after undergoing criticism and debate from various schools of thought. These examples demonstrate that scientific revolutions are not necessarily limited to abrupt changes that occur within a short period of time.
The third limitation is that the concept of “paradigm abandonment” is somewhat ambiguous. Kuhn explains that when a new paradigm emerges, the existing one is abandoned, but he did not clearly define the scope or meaning of this abandonment. For example, in the past, it was believed that light propagated through a medium called the ether, but due to various experimental results and the emergence of the theory of relativity, the concept of the ether ceased to be accepted by the scientific community. So, has the concept of the ether completely disappeared from the history of science? Or is there no possibility that it might be reused in a new theoretical context in the future? If a past concept can be reinterpreted with a different meaning within a new theory, it is also unclear whether this should be viewed as the revival of the existing paradigm or as an entirely new paradigm. These questions demonstrate the need to define the concept of “paradigm abandonment” more specifically.
The fourth limitation is that there is insufficient explanation of how anomalies develop into crises. Anomalies refer to observational results or theoretical problems that are difficult to explain within the existing paradigm. However, scientists do not initially regard these anomalies as serious problems, as most expect them to be resolved through future research. So, through what process do these anomalies develop to the point where the entire scientific community recognizes a crisis?
Kuhn explains that a crisis arises when anomalies accumulate in a complex manner, and he attempted to interpret this through a psychological approach. Generally, the more frequently people experience a particular phenomenon, the more strongly they perceive it. Similarly, when scientists repeatedly encounter anomalies, their trust in the existing paradigm weakens, and they begin to feel a sense of crisis. However, the argument that a sense of crisis leading to a scientific revolution is formed simply by repeatedly recognizing anomalies is somewhat insufficient. I believe a more specific explanation is needed regarding the conditions under which the entire scientific community abandons the existing paradigm.
So far, we have examined several limitations of Thomas Kuhn’s theory. First, we confirmed that there are cases that the structure of scientific revolutions fails to adequately explain. We have also seen that scientific revolutions do not necessarily occur in a radical manner. Third, we pointed out that the scope and meaning of paradigm abandonment are somewhat ambiguous. Finally, we noted that the theory does not sufficiently explain the process by which anomalies develop into a crisis. If these limitations can be addressed, Thomas Kuhn’s theory of scientific revolutions could be applied more broadly to understanding the development of science.
