The Structure of Scientific Revolutions

by

Thomas S. Kuhn

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The Structure of Scientific Revolutions: Chapter 4 Summary & Analysis

Summary
Analysis
Kuhn reiterates that normal science is not interested in novelty—and in fact, discoveries that might upend the paradigm are often ignored or actively discounted. Kuhn then seeks to understand why scientists are so passionate about doing normal science. He argues that this kind of research allows scientists to “achiev[e] the anticipated in a new way”; in other words, normal science is about “puzzle-solving.” Just as a jigsaw puzzle is a rewarding way of completing a pre-determined picture, Kuhn posits that normal science is an exciting method of proving what is already known.
Kuhn’s jigsaw puzzle metaphor here is tremendously useful: each time someone begins a puzzle, they are trying to arrive at a predetermined solution—the picture on the box. However, no two people will solve the puzzle the same way; some might move faster than others, and everyone has a different strategy. In this sense, they’re “achieving the anticipated in a new way.” In the same way, normal scientists are arriving at familiar conclusions through their own novel, individual processes.
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Quotes
Importantly, many problems that people were trying to solve in the pre-paradigm era are dismissed once the paradigm comes into power. In this way, the paradigm further limits what kinds of questions and answers are acceptable (and thus tries to prevent itself from being invalidated or overturned). Kuhn thus believes that individual scientists are motivated less by a desire to be useful to the world and more by a desire to prove their problem-solving skills.
Paradigms focus scientists’ attention on a set of data—and at the same time, they turn scientists’ attention away from facts that might confuse or disrupt the paradigm. Paradigms are therefore self-perpetuating. It is also important to note Kuhn’s focus on scientists’ humanity here, as he turns attention to what motivates this kind of work. He suggests that scientists are driven more by a desire for people to admire their intelligence and skill than by altruism.
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Continuing his jigsaw puzzle metaphor, Kuhn suggests that just as puzzles have rules (each piece must be turned face-up and interlocked with the others), so do paradigms. The most obvious kind of rule in a paradigm is the explicit laws associated with it: Newton’s laws, for instance, or the laws of thermodynamics. 
One of the main ways paradigms unite scientists is through these basic shared rules. (A famous example would be E = mc^2, Einstein’s physics equation that describes the relationship between mass and energy.) These rules allow scientists to set up problems and find solutions in a way that is consistent throughout the discipline.
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There are two other categories of rules: first, paradigms generally dictate what methods and technologies should be used to glean information. Second, there are “higher-level, quasi-metaphysical” beliefs that guide each paradigm. For example, Cartesian thinking (pioneered by René Descartes) told scientists that the entire world could be understood in terms of small molecular bodies interacting with one another. This belief gave scientists both a metaphysical understanding of the fabric of the universe and concrete way of solving problems.
Since scientists sharing a paradigm are looking for the same kind of information, it makes sense that they would use the same technologies and techniques. Importantly, though, scientists also share less tangible beliefs about the universe. Kuhn will later argue that because paradigms contain these “metaphysical” arguments about the world, scientists are affected not just professionally but personally when their paradigms are questioned. 
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Rules are important, but Kuhn does not think a paradigm is defined merely by its most important rules. Instead, he suggests that paradigms can still shape normal scientific work even in the absence of specific laws or methods.
Kuhn explains this more later, but he’s hinting at what he will later label as the concept of “tacit knowledge”: the idea that paradigms can be internalized and repeated through problem-solving, not just through explicit statements and laws.
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