The Structure of Scientific Revolutions

Kuhn challenges the old idea that science progresses through a steady build-up of facts. Instead, he suggests that science works within 'paradigms'—shared ways of thinking, theories, methods, and even basic assumptions that define what counts as a valid problem and solution in a scientific group. Most scientific work, 'normal science,' involves solving puzzles within these established paradigms. But when too many problems arise that the current framework cannot explain, a crisis begins. This eventually leads to a 'scientific revolutio...

Kuhn states that most scientific activity, 'normal science,' does not question basic theories. Instead, it refines, expands, and confirms the existing paradigm. Scientists in normal science are like puzzle-solvers, working within a set of rules and ideas to reach expected results. They aim to explain the paradigm more clearly, measure known things more precisely, and fix small issues. This focused, conservative stage is important for detailed study and gathering data, but it also makes scientists resistant to problems that threaten th...

Anomalies are observations or events that do not fit with the current paradigm. At first, scientists try to explain them away or slightly change the paradigm to include them. But when anomalies continue, grow, and cannot be solved, they cause a 'crisis.' This crisis means a loss of belief in the current paradigm's ability to solve basic problems, many new theories appearing, and more debate about the field's foundations. This time of insecurity and intellectual activity is needed before a scientific revolution, as it shows that the ol...

Perhaps Kuhn's most debated idea, 'incommensurability,' suggests that different paradigms are fundamentally incompatible and cannot be fully translated into each other. This is not just about different theories, but different ideas, problem sets, observation standards, and even the meaning of words. When a paradigm shifts, the world itself looks different. What was a 'fact' or a 'problem' in the old paradigm might no longer exist or take on a completely new meaning in the new one. This makes objective, logical comparison between parad...

Kuhn stresses that science is a group activity. Paradigms are not just individual theories but shared beliefs of a scientific community. Adopting a new paradigm during a revolution is not a purely individual, rational decision but a collective one, often involving persuasion, intellectual change, and the influence of senior figures. The community's agreement validates a paradigm, and its collapse during a crisis shows a collective loss of faith. New paradigms gain acceptance when they attract enough followers, often younger scientists...

A radical point of Kuhn's work is its challenge to the idea that science is steadily moving towards an objective, ultimate truth about nature. Because paradigms are incompatible, and each defines its own problems and solutions, a new paradigm is not necessarily 'truer' than the old one in an absolute sense. Instead, it is more effective at solving the problems that caused the crisis, or it opens new research paths that were previously unthinkable. Kuhn compares scientific development to biological evolution: it is a process of increas...

Kuhn describes a 'pre-paradigm' period in the early stages of a scientific field. During this time, there is no widely accepted theoretical framework, no shared method, and no agreement on what counts as important problems or valid evidence. Instead, many competing schools of thought exist, each with its own ideas and approaches. Data collection tends to be random and unfocused, as there is no guiding paradigm to direct inquiry. This period has constant debate over basics and a lack of cumulative progress. Only when one school of thou...

Kuhn explains that a 'paradigm' is not just a set of clear rules or theories, but also includes 'exemplars'—specific problem-solutions that students learn during their training. These exemplars act as models, teaching scientists how to 'see' the world in a certain way and how to approach new problems by comparison. Learning a paradigm is less about memorizing abstract rules and more about developing an intuitive understanding through practice, like an apprentice learning a trade. This focus on unspoken knowledge and shared examples he...

A common point in Kuhn's analysis is the strong resistance new paradigms face from established scientists. This is not necessarily due to irrationality, but because scientists have put their careers, reputations, and intellectual effort into the current paradigm. Their research questions, experiment designs, and even their understanding of basic concepts depend on the old framework. Adopting a new paradigm often means relearning their field, invalidating past work, and accepting a different worldview—a very unsettling idea. As a resul...

Kuhn's model shows scientific development as a cycle rather than a straight line. It moves from a pre-paradigm state (for new fields) to a period of 'normal science' guided by a main paradigm. As problems build up, this leads to a 'crisis,' eventually ending in a 'scientific revolution' where a new paradigm replaces the old. Once the new paradigm is established, a fresh period of 'normal science' begins, focusing on explaining and expanding the new framework, until new problems eventually appear, starting the next crisis and revolutio...