Karl Popper and Thomas Kuhn: How do we explain the nature of science?

Popper and Kuhn have different explanations for the nature and development of science. Popper emphasizes disprovability, while Kuhn emphasizes paradigm shifts. This article compares the two theories and discusses different methodologies for explaining science.

 

For many students, textbooks are the primary source for studying. In order to learn, textbooks need to have the right content and complete explanations. People naturally accept the content as truth, especially when it comes to math and science textbooks. They teach scientific facts that have been discovered by countless mathematicians and scientists in the past, so we take them for granted and learn them.
But before these facts were recognized as truth, we didn’t know how the world worked. Simply put, much of what is written in science textbooks was just one of many hypotheses, not truths, a few hundred years ago. Before these hypotheses became accepted as fact, countless scientists went through a process of testing and proving them, and eventually finalized several theories to explain the world. We can trace their work through the history of science and understand how theories evolve.
Several philosophers of science have developed different theories about how science develops and what science is inherently. Karl Popper and Thomas Kuhn are two of the most widely recognized philosophers of science. Their theories explain what we call science and how it has changed over time, but they have very different views. Popper criticized Kuhn’s work in a 1965 symposium at the International Society for the Philosophy of Science. So which of the two arguments is the more correct explanation? In this article, I will discuss how both arguments explain science and how science should be explained.
First, let’s review Popper’s theory. The most fundamental term in Popper’s description of science is “disprovability”. Let’s look at some common examples to see what he means.

– It will rain in the future.
– Crows are black.

Consider these two propositions. Both propositions can be meaningful to a positivist and are based on verifiability. In the case of the first proposition, we can observe that it will rain, and in the case of the second, we can find a crow and verify that it is black. However, the first proposition is meaningless in Popper’s view because we cannot disprove it. An unprovable proposition does not tell us anything useful, and therefore has no meaning. The second proposition is disprovable. We simply need to find a crow that is not black. If a white crow is found, the proposition can be modified and further developed.
This is Popper’s argument for using disprovability as a criterion for distinguishing science from non-science. “It is logically inadmissible to deduce theories from empirically verified monadic statements. Therefore, theories are never empirically verifiable,” and argued that the distinction should be disprovability, not verifiability.
Popper also said that methodological decisions in science are inevitable. Here, methodological rules are considered conventions and described as rules of the game of empirical science. Furthermore, the supreme rule for determining methodological rules is that other rules of scientific procedure must be devised in such a way that they do not prevent any statement of science from being disproved. Positivists were skeptical about methodology because they didn’t like the idea that there could be meaningful issues outside the realm of empirical science, but Popper argues that if everything else is meaningless except the problems of natural science, then debates about the concept of meaning will also prove meaningless, so there must be methodology.
Now let’s look at Kuhn’s theory. Kuhn refers to the formation, change, etc. of scientific theories as “normal science”. Normal science refers to research activities that are firmly grounded in one or more past scientific achievements. These scientific achievements are called paradigms. When a society of scientists accepts a paradigm that enables their theories and research, it enters the normal science phase, which is characterized by a puzzle-solving-like process: there are set rules, like solving a puzzle, and the problem is solved within those rules. When a problem that cannot be solved within the paradigm appears, a new paradigm emerges that is different from the existing paradigm. The survivors of the new paradigms overthrow the existing paradigms and become newly accepted, a process Kuhn calls revolution.
The existing paradigms and new paradigms mentioned above have the property of incommitment. In the process of revolution and paradigm shift, new concepts or claims cannot be strictly compared to old concepts or claims. A typical example of this is the transition of the concept of celestial bodies from epicycles to heliocentrism. The transition from heliocentrism to geocentrism can be described as a process of tearing down the old theory and building a new one, rather than adding to the wall of heliocentrism.
Even if you take a quick look at Popper and Kuhn’s respective arguments, you can see that they have very different ways of looking at science. Kuhn is more concerned with how scientific theories are accepted and changed by people, while Popper is more concerned with whether theories have scientific meaning. Because of the different emphases, it may not be possible to make clear comparisons and determine which is right or wrong. However, we can talk about the question of what science is because it’s something that both philosophers talk about.
Let’s start with Popper’s idea of disprovability. For Popper, science requires that propositions that cannot be disproved are unscientific, and that scientific statements must be testable. The crow proposition from earlier illustrates this well. But what about cases where it is impossible for scientists to disprove empirically? The first thing that comes to mind is the thought experiment. Thought experiments are exactly what they sound like: an imaginary experiment in which we can’t directly verify that the proposition associated with the outcome of the experiment is true. In other words, the proposition is empirically impossible to disprove. Galilei’s thought experiment on inertia led to propositions that describe facts that are already proven to be true by theories such as the law of inertia, the law of conservation of energy, and so on. Since we can’t replicate them in a laboratory setting, empirical disprovals are virtually impossible. The debate between Bohr and Einstein over the Copenhagen interpretation of quantum mechanics is similar. Here, the experiment Einstein presents for refutation is also a thought experiment. In this case, it is a practically impossible experiment, even more difficult to implement than Galilei’s thought experiment, so it cannot be performed empirically and would be impossible to disprove (and it can only be refuted by performing a thought experiment, which is what Bohr did). Nevertheless, no one would call their debate unscientific. Of course, most scientific theories are disprovable, so Popper is not wrong.
But what about Kuhn’s normal science? In the case of the thought experiment above, Kuhn’s theory would allow us to treat it as a paradigm. The paradigm created by Galilei is not in error if it can be explained as a theory that triumphs over the existing paradigm and becomes a theory. So is Kuhn’s theory more correct? Probably not. To answer this, let’s go back to the field of quantum mechanics. The theory of quantum mechanics is that the old paradigm, Newtonian mechanics, didn’t work well in the microscopic world, so a new paradigm, quantum mechanics, was created. Quantum mechanics was determined to be the right theory and became a legitimate science. According to Kuhn’s theory, the paradigm of quantum mechanics triumphed over the paradigm of Newtonian mechanics and became the new normal science in its place. However, we do not say that Newtonian mechanics is completely wrong, and physics in the macroscopic world is still described by Newtonian mechanics. In other words, the two theories coexist in the field of physics. Of course, we can say that the concept of quantum mechanics has revolutionized the microscopic world, but it hasn’t replaced all the old paradigms.
According to the logic presented above, we can’t say which of the two theories is right. According to the examples given, there are scientific events that are difficult to explain with each theory, and therefore it would be difficult to explain science as a whole. A theory that fully explains science should be able to apply well to all the fields included in science. However, since the fields of science are so diverse, and the cases in each field are all different in nature, it is very difficult to explain everything with a single theory. In fact, current philosophers of science focus on meta-discourse about individual sciences rather than discussing science in general. Therefore, for each scientific field, there will be an appropriate philosophy of science theory, and Popper’s theory or Kuhn’s theory could be one of them. To use the example given earlier, the development of science in relation to thought experiments can be explained by Popper’s theory of normal science, while the development of quantum mechanics can be explained by the process of refinement of theories by continuous disprovals.
Science cannot be explained by just one theory. Although the theories proposed by Popper and Kuhn are currently the most widely recognized and best able to explain science, we can see that they do not explain all phenomena. It is also true that each theory can explain phenomena well in certain areas. Therefore, I will argue that to fully explain science, we should not think of only one theory, but rather merge the best explanations for many situations.