Extraordinary research – When enough significant anomalies have accrued against a current paradigm, the scientific discipline is thrown into a state of crisis.Under normal science, scientists encounter anomalies that cannot be explained by the universally accepted paradigm within which scientific progress has thereto been made. A chemist and a physicist might operate with different paradigms of what a helium atom is. Kuhn stresses that, rather than being monolithic, the paradigms that define normal science can be particular to different people. Insofar as paradigms are useful, they expand both the scope and the tools with which scientists do research. Some examples of dominant paradigms that Kuhn gives are: Newtonian physics, caloric theory, and the theory of electromagnetism. This paradigm is characterized by a set of theories and ideas that define what is possible and rational to do, giving scientists a clear set of tools to approach certain problems.

Normal science – In this stage, which Kuhn sees as most prominent in science, a dominant paradigm is active.In his 1962 book The Structure of Scientific Revolutions, Kuhn explains the development of paradigm shifts in science into four stages: Original usage Kuhn used the duck-rabbit optical illusion, made famous by Wittgenstein, to demonstrate the way in which a paradigm shift could cause one to see the same information in an entirely different way. In the 20th century, new developments in the basic concepts of mathematics, physics, and biology revitalized interest in the question among scholars.

Kant used the phrase 'revolution of the way of thinking' ( Revolution der Denkart) to refer to Greek mathematics and Newtonian physics. The nature of scientific revolutions has been studied by modern philosophy since Immanuel Kant used the phrase in the preface to the second edition of his Critique of Pure Reason (1787). This is precisely the second meaning of the term 'paradigm', which Kuhn considered the most new and profound, though it is in truth the oldest. Normal science does not mean at all a science guided by a coherent system of rules, on the contrary, the rules can be derived from the paradigms, but the paradigms can guide the investigation also in the absence of rules. That is to say, the science which can decide if a certain problem will be considered scientific or not. Thus the question is for Kuhn to investigate by means of the paradigm what makes possible the constitution of what he calls 'normal science'. stands for the explicit rules and thus defines a coherent tradition of investigation.

In the second sense, the paradigm is a single element of a whole, say for instance Newton’s Principia, which, acting as a common model or an example. In the first one, 'paradigm' designates what the members of a certain scientific community have in common, that is to say, the whole of techniques, patents and values shared by the members of the community. Kuhn acknowledges having used the term 'paradigm' in two different meanings. Paradigm shifts arise when the dominant paradigm under which normal science operates is rendered incompatible with new phenomena, facilitating the adoption of a new theory or paradigm. Kuhn contrasts paradigm shifts, which characterize a Scientific Revolution, to the activity of normal science, which he describes as scientific work done within a prevailing framework or paradigm. Kuhn presented his notion of a paradigm shift in his influential book The Structure of Scientific Revolutions (1962). Even though Kuhn restricted the use of the term to the natural sciences, the concept of a paradigm shift has also been used in numerous non-scientific contexts to describe a profound change in a fundamental model or perception of events. It is a concept in the philosophy of science that was introduced and brought into the common lexicon by the American physicist and philosopher Thomas Kuhn. A paradigm shift is a fundamental change in the basic concepts and experimental practices of a scientific discipline.

Physical activity paradigm shift