Historically, the notion of science has been that of a truth-seeking venture. That is, with each stop forward science takes, scientists move closer and closer to understanding the what, when, why and how of it all. The idea is that science allows scientists to see the world as it is. And this is made possible because science is continuous and cumulative.
Science is a like a house. It is built upon the already established foundations of the previous generation of scientists. But of course, this is not Kuhn’s notion of science. His notion of science is rather dichotomous compared to the popular view.
To a degree, the traditional views of how science progresses is still salient in the minds of mainstream America; that is, continuous and cumulative. However, Kuhn’s notion of scientific revolutions is quite different. Perhaps dichotomous is a better term. Kuhn argues that science is discontinuous. This means there ar periods where science is not cumulating because the opposing paradigms, in the middle of the scientific revolution, are competing to see which paradigm has the tool kit to solve the recognized anomalies.
Kuhn argues that science is not cumulative, at least not during scientific revolutions. He agrees that science is cumulative and continuous during the “normal science” phase before and after the revolution has occurred. But science is neither continuous nor cumulative during the revolution. As Kuhn explains in The Structure of Scientific Revolutions
…scientific revolutions are here taken to be non-cumulative developmental episodes in which an older paradigm is replaced in whole or in part by an incompatible new one…
Thus, the consequence of this idea is that the information in the old scientific paradigm is left behind and not brought into the new scientific paradigm – discontinuity between the old and new. And this part of the notion leads back to the idea of truth. What is truth? This part of the notion will be addressed in the end. But first, how do revolutions emerge in Kuhnian philosophy?
So how do revolutions come about? Originally, it was thought that science progressed in a continuous and cumulative manner; that is, concepts, theories, and other scientific elements are built upon the preceding concepts and theories and so on and so forth in the future with little to no discontinuity. However, Kuhn challenged that belief. In contrast, Kuhn argued that science was discontinuous and the ideas of the new paradigm were not compatible with the old paradigm. To help explain this idea, Kuhn’s scientific revolution could be viewed in five stages.
The first is what Kuhn calls “normal science.” This is where there is a dominant paradigm, which provides the necessary tools to solve scientific puzzles. For example, Newtonian physics allowed scientists of the 17th, 18th, 19th, and early 20th centuries to understand the physical world in a new way and it provided reasons for why and how physical objects act the way they do. However, anomalies in Newtonian physics provided was presented in two stages, special and general relativity, which helped to solve the anomalies from the previous Newtonian paradigm.
The anomalous stage is followed by the crisis stage. This is where the old ways of doing things – approaches, methods, and procedures – are slowly but surely tested for compatibility or to potentially replace the preceding techniques. But as anomalies continue to be produced by the former paradigm and the new methodologies that accompany the new paradigm address and solve the anomalies of the old; thus, the old makes way for the new. This is the paradigm shift.
From here, the scientific revolution completes its journey when the paradigm shift begins to produce textbooks for the next generation of scientists who will solve puzzles under the guise of the new paradigm, or as Kuhn refers to it, “normal science.” This of course infers that there is not a “normal science.” This is because the science that came before is incommensurable.
According to Kuhn, scientific paradigms are incompatible. They are, in another word, incommensurable. And the consequence of this notion is great. In comparing an old theory to a new theory, Kuhn states that the new theory benefits from
…accuracy of prediction, particularly of quantitative prediction; the balance between esoteric and everyday subject matter; and the number of different problems solved…
Thus, the new paradigm provides its practitioners with the necessary tools to address the previous anomalies brought about by the previous paradigm for which the old paradigm tools could not solve. As a further consequence, “the two are not logically compatible,” for the old paradigm has no place in this world. But it is not just the incompatibility of tolls from one paradigm to another. It is also the incompatibility of the meaning of terms and the incompatibility of how scientists view the world.
As Kuhn explains, “the proponents of competing paradigms practice their trades in different worlds.” Hence one practitioner sees the world as a falling body and the other sees it as a swinging pendulum. And this is another important point for what the incommensurability thesis implies about scientific change. The falling body and swinging pendulum perpetuate a dichotomous perception of the world. Who is correct? Who is closer to the truth?
A consequence of the different paradigms between a falling body and a swinging pendulum is that there are two truths at the very least. Ironically, Kuhn’s notion of science and the traditional notion of science illustrate this dichotomy of truth best. So is it indeed the case that science is only continuous and cumulative during “normal science?”
Or is it the case that science is continuous and cumulative throughout the aggregate of history? Or is Kuhn ultimately right; that is, truth is in the eye of the beholder? According to Kuhn, scientists view the world in fundamentally different ways. And this is fine. But if the anomalies of one paradigm are solved by the other paradigm, then how is it there are competing or multiple truths?