The Structure of Scientific Revolutions

by

Thomas S. Kuhn

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Normal Science Term Analysis

Once a paradigm is in place, normal science is the work of strengthening, proving and applying that paradigm. Normal science allows scientists to build on one another’s work and to agree on a limited set of questions, tools, and methodologies; this is the kind of work that the vast majority of scientists do. At the same time, normal science—which is taught through textbooks, and which emphasizes puzzle-solving—discourages original thinking and new discovery.

Normal Science Quotes in The Structure of Scientific Revolutions

The The Structure of Scientific Revolutions quotes below are all either spoken by Normal Science or refer to Normal Science. For each quote, you can also see the other terms and themes related to it (each theme is indicated by its own dot and icon, like this one:
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). Note: all page numbers and citation info for the quotes below refer to the University of Chicago Press edition of The Structure of Scientific Revolutions published in 2012.
Chapter 3 Quotes

Mopping-up operations are what engage most scientists throughout their careers. They constitute what I am here calling normal science. Closely examined, whether historically or in the contemporary laboratory, that enterprise seems an attempt to force nature into the preformed and relatively inflexible box that the paradigm supplies. No part of the aim of normal science is to call forth new sorts of phenomena; indeed those that will not fit the box are often not seen at all.

Related Characters: Thomas Kuhn (speaker)
Page Number: 24
Explanation and Analysis:
Chapter 4 Quotes

Once engaged, his motivation is of a rather different sort. What then challenges him is the conviction that, if only he is skillful enough, he will succeed in solving a puzzle that no one before has solved or solved so well. Many of the greatest scientific minds have devoted all of their professional attention to demanding puzzles of this sort. On most occasions any particular field of specialization offers nothing else to do, a fact that makes it no less fascinating to the proper sort of addict.

Related Characters: Thomas Kuhn (speaker)
Page Number: 38
Explanation and Analysis:
Chapter 5 Quotes

That process of learning by finger exercise or by doing continues throughout the process of professional initiation […] One is at liberty to suppose that somewhere along the way the scientist has intuitively abstracted rules of the game for himself, but there is little reason to believe it. Though many scientists talk easily and well about the particular individual hypotheses that underlie a concrete piece of current research, they are little better than laymen at characterizing the established bases of their field, its legitimate problems and methods.

Related Characters: Thomas Kuhn (speaker)
Page Number: 47
Explanation and Analysis:

An investigator who hoped to learn something about what scientists took the atomic theory to be asked a distinguished physicist and an eminent chemist whether a single atom of helium was or was not a molecule. Both answered without hesitation, but their answers were not the same. For the chemist the atom of helium was a molecule because it behaved like one with respect to the kinetic theory of gases. For the physicist, on the other hand, the helium atom was not a molecule because it displayed no molecular spectrum. Presumably both men were talking of the same particle, but they were viewing it through their own research training and practice. Their experience in problem-solving told them what a molecule must be.

Related Characters: Thomas Kuhn (speaker)
Page Number: 51
Explanation and Analysis:
Chapter 6 Quotes

New and unsuspected phenomena are, however, repeatedly uncovered by scientific research, and radical new theories have again and again been invented by scientists. […] If this characteristic of science is to be reconciled with what has already been said, then research under a paradigm must be a particularly effective way of inducing paradigm change. That is what fundamental novelties of fact and theory do. Produced inadvertently by a game played under one set of rules, their assimilation requires the elaboration of another set.

Related Characters: Thomas Kuhn (speaker)
Page Number: 53
Explanation and Analysis:

Anomaly appears only against the background provided by the paradigm. The more precise and far-reaching that paradigm is, the more sensitive an indicator it provides of anomaly and hence of an occasion for paradigm change.

Related Characters: Thomas Kuhn (speaker)
Page Number: 65
Explanation and Analysis:
Chapter 8 Quotes

When acute, this situation is sometimes recognized by the scientists involved. Copernicus complained that in his day astronomers were so “inconsistent in these [astronomical] investigations . . . that they cannot even explain or observe the constant length of the seasonal year.” “With them,” he continued, “it is as though an artist were to gather the hands, feet, head and other members for his images from diverse models, each part excellently drawn, but not related to a single body, and since they in no way match each other, the result would be monster rather than man.” Einstein, restricted by current usage to less florid language, wrote only, “It was as if the ground had been pulled out from under one, with no firm foundation to be seen anywhere, upon which one could have built.”

Related Characters: Thomas Kuhn (speaker), Nicolaus Copernicus, Albert Einstein
Related Symbols: Jigsaw Puzzles
Page Number: 83
Explanation and Analysis:

The marks on paper that were first seen as a bird are now seen as an antelope, or vice versa. That parallel can be misleading. […] the scientist does not preserve the gestalt subject’s freedom to switch back and forth between ways of seeing. Nevertheless, the switch of gestalt, particularly because it is today so familiar, is a useful elementary prototype for what occurs in full-scale paradigm shift.

Related Characters: Thomas Kuhn (speaker), Aristotle, Galileo Galilei
Related Symbols: Bird/Antelope
Page Number: 85
Explanation and Analysis:

Instead, the new paradigm, or a sufficient hint to permit later articulation, emerges all at once, sometimes in the middle of the night, in the mind of a man deeply immersed in crisis. […] Almost always the men who achieve these fundamental inventions of a new paradigm have been either very young or very new to the field whose paradigm they change. And perhaps that point need not have been made explicit, for obviously these are the men who, being little committed by prior practice to the traditional rules of normal science, are particularly likely to see that those rules no longer define a playable game and to conceive another set that can replace them.

Related Characters: Thomas Kuhn (speaker)
Page Number: 90
Explanation and Analysis:
Chapter 9 Quotes

As in political revolutions, so in paradigm choice—there is no standard higher than the assent of the relevant community.

Related Characters: Thomas Kuhn (speaker)
Page Number: 94
Explanation and Analysis:
Chapter 10 Quotes

Looking at the moon, the convert to Copernicanism does not say, “I used to see a planet, but now I see a satellite.” That locution would imply a sense in which the Ptolemaic system had once been correct. Instead, a convert to the new astronomy says, “I once took the moon to be (or saw the moon as) a planet, but I was mistaken.”

Related Characters: Thomas Kuhn (speaker), Nicolaus Copernicus
Page Number: 115
Explanation and Analysis:

Chemists could not, therefore, simply accept Dalton’s theory on the evidence, for much of that was still negative. Instead, even after accepting the theory, they had still to beat nature into line, a process which, in the event, took almost another generation. When it was done, even the percentage composition of well-known compounds was different. The data themselves had changed. That is the last of the senses in which we may want to say that after a revolution scientists work in a different world.

Related Characters: Thomas Kuhn (speaker), John Dalton
Page Number: 134
Explanation and Analysis:
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Normal Science Term Timeline in The Structure of Scientific Revolutions

The timeline below shows where the term Normal Science appears in The Structure of Scientific Revolutions. The colored dots and icons indicate which themes are associated with that appearance.
Chapter 1. Introduction: A Role for History
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...which these arbitrary assumptions are passed down through formal education is, in Kuhn’s words, “ normal science .” Normal science “is predicated on the assumption that the scientific community knows what the... (full context)
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...narrative of incremental progress, then, Kuhn sees scientific history as a cycle: scientific revolutions interrupt normal science , which leads to a new kind of normal science, which is then interrupted again,... (full context)
Chapter 2. The Route to Normal Science
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Kuhn begins with a definition: “ normal science ” is the everyday practice of scientific research, an everyday practice that is usually on... (full context)
Chapter 3. The Nature of Normal Science
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...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... (full context)
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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... (full context)
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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... (full context)
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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... (full context)
Chapter 4. Normal Science as Puzzle-solving
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Kuhn reiterates that normal science is not interested in novelty—and in fact, discoveries that might upend the paradigm are often... (full context)
Chapter 5. The Priority of Paradigms
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Finally, Kuhn argues that rules are more important to normal science when paradigms are starting to collapse (just before and during scientific revolutions). But when paradigms... (full context)
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...which one group rethinks its paradigm while other larger groups continue with their practice of normal science . And fascinatingly, while rules tend to be more universal, paradigms—which draw on a shared... (full context)
Chapter 6. Anomaly and the Emergence of Scientific Discovery
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When people think of science, they are usually picturing normal science : it is cumulative, linear and very successful at finding answers. But how does normal... (full context)
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...for scientists to spot an anomaly. This is why scientific revolutions always come out of normal science . (full context)
Chapter 8. The Response to Crisis
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...be seen anywhere.” But more often than not, crisis is not explicitly named. And indeed, normal science is often able to resolve crisis. In other cases, scientists give up, deciding they do... (full context)
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Kuhn then begins to describe the process of “extraordinary science.” In contrast to normal science , which tries to reject or resolve the anomaly, extraordinary science works with the anomaly... (full context)
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The first step of extraordinary science, Kuhn argues, is to test out normal science by “push[ing] the rules” of a paradigm as far as they will go. The second... (full context)
Chapter 10. Revolutions as Changes of World View
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...scientific student’s perception of the world “is determined jointly by the environment and the particular normal-scientific tradition that the student has been trained to pursue.” When a paradigm shift occurs, therefore,... (full context)
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...was ultimately the result of a “lightning flash” change in perception. In other words, if normal science leads to a crisis, it can never itself lead to a new paradigm. Instead, new... (full context)
Chapter 11. The Invisibility of Revolutions
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...philosophy of science all focus on presenting the coherent laws and truths acknowledged by the “normal-scientific tradition” of the time. (full context)
Chapter 12. The Resolution of Revolutions
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...Kuhn believes that a paradigm shift is “a conversion experience that cannot be forced.” If normal science is effective because it gives scientists confidence in their beliefs, then uprooting those beliefs in... (full context)
Chapter 13. Progress through Revolutions
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...in these fields views that as disqualifying or negative. This disagreement is not possible in normal science because it is guided by a single coherent paradigm. (full context)
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Rather than condemning this education, however, Kuhn notes that it prepares students for normal science . And because normal science is what allows for moments of crisis (and subsequent scientific... (full context)