Thomas Kuhn's Structure of Scientific Revolutions Explained

Introduction to Normal Science and Paradigms

Thomas Kuhn's highly influential book, The Structure of Scientific Revolutions, proposes a model — or pattern — for the evolution of science throughout the ages. Kuhn makes use of specific concepts and a careful structure across thirteen chapters, each treating in turn the basic aspects of the progress of science over time.

First, Kuhn (1996) introduces the notion of normal science — the science that bases its research on previous work recognized as valid by a scientific community (p. 10). It is the structure of normal science that the book proposes to investigate. Furthermore, Kuhn (1996) argues that the most salient feature of scientific evolution over time is that science does not progress through leaps or through unrelated sets of investigations. On the contrary, scientific research is always conducted under a paradigm; all research is grounded in previous scientific data. The scientific paradigm can be defined as a certain common pattern in scientific research, or a set of accepted world-views held as true for a period of time — a body of common beliefs about the world, based on past research.

According to Kuhn (1996), scientific research without paradigms does exist, but it is a sign of immaturity in a given scientific field (p. 11). When a scientific paradigm establishes itself within a domain, it usually signals that the field has achieved a theory that successfully — though not completely — matches observable natural phenomena. The way a paradigm imposes itself over competing paradigms has two main characteristics in Kuhn's view: it is sufficiently innovative to explain certain phenomena and thereby attract a considerable number of adherents, and it simultaneously leaves room for further research, meaning its assumptions must be valid enough to support additional developments from its premises (p. 10).

The main premise for normal science is therefore the existence of paradigms — that is, consensus with regard to the phenomena under investigation. Science also evolves through a series of paradigm shifts, in which old world-views are replaced by new ones. This is why, for some scientific phenomena, the appearance of the first paradigm is also the appearance of the first coherent or valid answer to its problems.

As Kuhn exemplifies, optics had no paradigm before Newton and therefore made no consistent progress until after the seventeenth century (p. 13). The lack of unity within a field of research — or the absence of commitment to shared assumptions — is clear evidence that no real progress has been made.

Paradigms as the Foundation of Scientific Progress

Kuhn (1996) emphasizes that the notion of a paradigm is far more apt to describe the consensus existing at a given time within a scientific field than is the idea that research simply obeys an exact set of rules. He speaks of the priority of paradigms over rules, arguing that there can be consensus or agreement on a scientific matter even while individual scientists give different accounts of the particular details that lead to a given solution (p. 44).

Normal science therefore agrees with respect to problem-solutions, not to the specific rules used to reach them. This is why the most important requirement for scientific progress is the existence of paradigms or consensus within a field — paradigms that are always oriented toward the solutions offered by theory, and not necessarily toward any fixed set of applicable rules.

Thus, Kuhn defines a scientific paradigm as a widely accepted world-view concerning the specific solutions that theory offers to naturally observed phenomena. The importance of the paradigm is easily appreciated when one realizes that, even when a paradigm proves completely inaccurate, it remains the most telling sign that a given science has made real progress and achieved maturity. Science always evolves through paradigm shifts — through patterned, not random, changes in world-views. A paradigm is therefore never abolished until a new one emerges to replace it.

The paradigm is thus the essential concept for theorizing scientific revolutions. Science evolves through revolutions, and revolutions appear when an old paradigm is substituted by a new one. The structure of scientific revolutions has as its primary organizing concept the scientific paradigm.

Normal Science as Puzzle-Solving

According to Kuhn (1996), normal science is essentially puzzle-solving: it does not aim at novelty or unexpected results. Even when research is directed toward the formulation of a new paradigm, the main concern is with the complex conceptual and instrumental framework that may be used to attain an outcome already foreseen (p. 36).

Research in normal science is thus very similar to solving a puzzle: the picture of the phenomenon under investigation may already be known, but the most appropriate path to the solution is not. The scientist therefore almost always focuses on the theoretical framework needed to explain an observable phenomenon.

Having established this, Kuhn (1996) directs his analysis to the way in which scientific revolutions occur within the context of normal science's puzzle-solving character. If normal science is not primarily concerned with discovery or novelty, then the question of how discovery actually arises must be posed.

Conclusion: The Universality of Scientific Revolutions

Scientific progress is essentially different from progress in other domains of human thought, such as art or the social sciences. The latter do not progress in the same way as science does, although they too employ the term paradigm to separate specific currents and trends of thought. Literature, for example, can speak of a Romantic paradigm with certain common features that is replaced by a new one representing the world differently. In science, however, the succession of paradigms leads to genuine progress, as one discovery leads to another; moreover, paradigms are sometimes completely replaced by new ones — something that does not occur in art, where older works still retain many valuable ideas.

The scientific path is thus characterized by more than mere changes in perception. Although perception, according to Kuhn (1996), is very important in science — to the point that the world itself can be said to change with a paradigm shift — it is not perception alone that transforms. The scientist must form a paradigm from what he or she observes, even though, many times, what is actually observed stays the same (p. 112).

Kuhn offers a revolutionary description of science and its progress, and his concepts of paradigm and paradigm shift have been used extensively across all fields of research. They remain the most widely employed framework for accounting for the way in which science evolves. Kuhn's theory of the structure of scientific revolutions is therefore highly pertinent for an accurate description of the past, present, and future of science and of the general manner in which it progresses.

Reference List

Kuhn, T. S. (1996). The structure of scientific revolutions. University of Chicago Press.