Karl Popper and Thomas Kuhn offer the most influential works written in the twentieth century on scientific discovery. Having been reported in the same century, they seem to have much in common in many ways. They both display an interest and concern for how science knowledge changes. Although Kuhn is widely regarded as a philosopher of science and Popper as a philosopher of logic, the two authors share an interest in how scientific theories change (Popper 43). However, their respective view on what motivates change differ radically. Popper thinks that the only way scientific knowledge can be reliable and progress is by falsification, while Kuhn argues that change happens due to normal science. It is important to note that the two authors do not view the process of scientific change in the same way. Popper refers to his concept of falsification as a “negative heuristic” (Popper 46). In contrast, Kuhn’s idea of normal science can be seen as a positive heuristic (Kuhn 124). Popper recognizes that if all scientific theories are falsifiable, they must eventually be falsified and replaced with another theory. He argues that scientific progress can only occur if scientists recognize such theories. In contrast, Kuhn acknowledges that science is a human activity and that while normal science can be defined as how scientists collectively work together, it necessarily has specific characteristics. This paper will analyze how Kuhn and Popper think that scientific knowledge changes, what they agree on, how they are different, and to what degree, if at all, can be seen as being in opposition to one another.
Popper and Kuhn Agreement and Disagreements about Scientific Knowledge Changes
Popper and Kuhn both recognize that scientific knowledge changes. Popper argues that scientific knowledge is progressing only if it can be tested, which means, of course, that it must be falsifiable (Popper 51). The only way to test a scientific theory is by testing its predictions, and if the theory does not make any falsifiable claims, then it cannot be tested. Kuhn argues for a different view. He agrees that scientific knowledge changes, but he holds that this change happens due to normal science. Normal science is held to progress in a non-falsifiable manner. He defines normal science as “how scientists collectively work together” (Kuhn 184).
Popper disagrees with this view, and he argues that while normal science is necessary for scientific progress, it is not sufficient for it. Kuhn’s theory on normal science is that it can be defined as the “way in which scientists collectively work together.” However, this definition is insufficient because it does not explain how it can be expected to progress. Popper argues that “scientists will only take up a falsified theory if they have decided that a new theory must take its place.” Kuhn agrees with this point, but he argues that scientists do not make this decision on their own (Kuhn 68). Instead, he thinks that ordinary scientific research and normal science are held together by “falsification by experiment,” which is carried out by the scientific community. In other words, Kuhn argues that normal science is an ongoing process rather than an individual decision. A critical difference between Kuhn and Popper is that Kuhn thinks that scientists are not necessarily good at recognizing that their theories must be replaced due to normal science. He writes, “To achieve a scientific revolution, there must be a considerable amount of difficulty in the transition from one paradigm to another” (Kuhn 154). This is because scientists do not always distinguish between a scientific theory and an unproven theory by themselves. Instead, they often adopt new theories from others. Therefore, if normal science accepts an unproven theory, this may lead to beliefs about what must be replaced with another theory. Popper disagrees with this view; scientists stick to their ideas (Popper 48). Therefore, if normal science accepts an unproven theory, this may not lead to beliefs about what must be replaced with another theory. Thus, the question of who decides to abandon a scientific theory and who decides which theories should be replaced is central to Popper’s approach.
There are significant differences between Popper and Kuhn concerning how scientific knowledge changes. We have already seen that Kuhn holds that change occurs due to normal science. He argues that a scientific community progresses only due to the process of falsification of one theory by another (Kuhn 221). Popper argues for a different view; he holds that the best way to test a scientific theory is by testing its predictions, and if the idea does not make any falsifiable claims, it cannot be tested. He argues for the view that scientific progress can only occur if scientists can recognize such theories (Popper 53). Popper, therefore, holds that progress occurs as a result of falsification. Science can only progress due to the change from one theory to another, not just from normal science, because this would create an infinite regress where theories must always be replaced with other theories. Popper argues that this is because science is not a natural process. Instead, the process of falsification attempts to make science artificially scientific. This can be contrasted with Kuhn’s view because he sees science as a natural process and normal science as the outcome of social change within science (Kuhn 231). Popper holds that falsification must occur by itself, while Kuhn believes it happens by itself or by sharing ideas between scientists.
In conclusion, Popper and Kuhn have different views about how scientific knowledge changes. Popper argues that this is because science progresses due to falsification, while Kuhn argues that it occurs due to normal science. Therefore, this difference is a critical issue concerning the debate between Popper and Kuhn. They also hold different views on how scientific knowledge changes. While Popper thinks that science progresses only by falsification, Kuhn has that it progresses due to normal science and current research. While Kuhn argues for the view that normal science is not only necessary for scientific progress but also sufficient in itself, Popper says that a scientific theory must be falsifiable before scientists accept it as such. While Kuhn works to explain how science changes while Popper tries to explain the role of falsification in this change, each approaches the issue from a different perspective. Both Popper and Kuhn attempt to account for the change in scientific knowledge, but they come to this issue differently. They agree that falsification can lead to knowledge changes, but they disagree about if this is the only way. Popper argues that falsification is the only way for theories to be accepted as scientific.
Kuhn, Thomas S. The structure of scientific revolutions. Vol. 111. University of Chicago Press: Chicago, 1970: 6-264.
Popper, Karl R. Normal science and its dangers. Cambridge: Cambridge University Press, 1970: 51-58.
Popper, Karl. Conjectures and refutations: The growth of scientific knowledge. Routledge, 2014: 43-51