The Structure of Scientific Revolutions

by

Thomas S. Kuhn

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The Structure of Scientific Revolutions: Chapter 3 Summary & Analysis

Summary
Analysis
Kuhn emphasizes that paradigms are often very limited when they emerge—they are successful not because they solve everything, but because they provide the tools that future scientists can use to tackle a variety of problems. Normal science is therefore a kind of “mopping-up” of the questions that the paradigm raises, in which scientists try to “force nature into the preformed and relatively inflexible box that the paradigm supplies.”
Paradigms provide a set of questions and a place to focus, but they do not provide specific numbers of data points. The “mop-up” work that Kuhn refers to involves applying these big ideas to variety of specific problems. However, scientists in normal science are not looking to test the paradigm; instead, they are looking to affirm the “inflexible” view that the paradigm already supplies.
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Again, Kuhn emphasizes that normal science actually discourages novelty and original thinking. But even as Kuhn criticizes normal science, he admits that it allows scientists to solve specific problems in a way that would be impossible without a guiding paradigm. There are three main kinds of knowledge that a paradigm allows its practitioners to focus on.
It is crucial to note that while Kuhn critiques textbook history, he does not critique normal science. Because it allows for specificity and quicker problem-solving, normal science is the foundation of most of the work scientists do.
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First, scientists working on normal science must figure out new ways to observe the relevant facts in their paradigm (e.g., star positions in astronomy or wave lengths in physics). To do this, they will create new tools and apparatuses.
Here, Kuhn explains how normal science can actually bring about innovation. Although normal science can box scientists into a certain paradigm, this, in turn, encourages them to come up new tools or methods in order to work within that paradigm.
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Second, scientists try and make nature line up with the paradigm theory’s predictions. Once again, this involves investing in and inventing brand-new machines and technologies to measure various quantities.
The initial idea behind a paradigm usually involves a lot of predictions. One of the most important ways scientists justify their paradigm is by seeing that these predictions are borne out (even if they have to invent new tools or techniques to do so).  
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Third, scientists look for the actual numbers or rules (“empirical work”) that make a paradigm theory applicable in the real world. Kuhn lists several examples of these kind of constants: there is Avogadro’s number in chemistry, or Boyle’s law in physics (both of which are named after the men who discovered them).
Paradigms begin with predictions and questions, not data. A big part of normal science is introducing these numbers or rules, which then form the basis of textbook problems—and so help educate the next generation of scientists in the paradigm.
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A lot of scientific work in Kuhn’s time involves scientists doing experiments to prove “points of contact between a theory and nature.” This is generally considered to be an elementary form of science, as it merely involves carrying out trials to affirm what a paradigm has already predicted.
Some parts of the work in normal science are more obviously “mop-up” work than other parts. In particular, experiments to prove already-known data are usually done by younger scientists (for example, a high school lab experiment). The purpose of these experiments isn’t to make a new discovery, but to observe an established theory play out in the real world.
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Another major part of normal science is responding to the imperfections of the paradigm’s first major discovery (what Kuhn calls “reformulating the paradigm”). For instance, when Newton’s theories about planets’ rotation neglected the gravitational force that planets exert on one another, many world-class mathematicians struggled to come up with a formula to explain this discrepancy. In the process, they discovered mathematical principles that improved many other fields of science and math. Kuhn thus argues that this kind of reformulation—which produces “a more precise paradigm”—is the most theoretical form of normal science.
Some elements of normal science at first seem to be about original discovery, though Kuhn argues that this is not really the case. The most advanced scientific work in normal science involves coming up with more concrete equations or applications that allow the paradigm’s theory to match up more closely with observable reality.
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