The Structure of Scientific Revolutions

by

Thomas S. Kuhn

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The Structure of Scientific Revolutions: Chapter 8 Summary & Analysis

Summary
Analysis
Though crisis causes scientists to abandon old paradigms, Kuhn believes that—at least according to the various historical examples he has studied—scientists never do so unless they have a new paradigm to replace the old one. To reject a paradigm without having another one is, Kuhn argues, “to reject science itself”; it would mean returning to a scattershot collection of opinions and beliefs.
Once scientists have some guiding theories and beliefs, they can no longer return to the confusing pre-paradigm era. In other words, once scientists have established some shared views, it is difficult to return to relying again only on their individual perceptions.
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But while anomalies lead to crises, counterinstances (or moments in which the paradigm does not behave exactly as expected) are an everyday part of normal science. Kuhn thus posits that there is no clean line between what is an anomaly and what is merely another challenging puzzle for scientists to solve. And often, when scientists are unable to solve these puzzles, their colleagues see it not as the failure of the paradigm but as the failure of that individual scientist. Moreover, sometimes anomalies are resolved by discoveries in another field that offer a surprising solution.
Kuhn clarifies that not every anomaly rises to the level of crisis. Just as it took 100 years for James Maxwell to transform an anomaly in Newton’s laws into a crisis, many anomalies are dismissed or resolved through new techniques and calculations. So, although some anomalies cause paradigm shifts, not all do.
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 Only very special kinds of anomalies, then, create crises. Sometimes this is because the anomaly has practical importance for society, as in the case of Copernicus (the Catholic Church was struggling to create an accurate calendar, and Copernicus was trying to figure out why). Sometimes, the anomaly grows more glaring as the field advances; sometimes, the anomaly cuts immediately and clearly to the heart of the paradigm. When a great many scientists have to pay attention to one anomaly, their responses to that anomaly start to conflict, and the paradigm begins to collapse.
Kuhn suggests that the closer an anomaly is to daily life, the harder it is to avoid or shrug off (as in the case of Copernicus and the calendar). And just as normal science makes anomalies easier to spot, paradigms help scientists come to consensus about which anomalies to pay attention to. Kuhn’s focus on the nature of scientific communities, which becomes more prominent later in his book, is reflected in his attention to how scientists choose what really counts as an important anomaly.
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Sometimes, scientists themselves recognize this breakdown: Einstein once said a moment of crisis in his field was “as if the ground had been pulled out from under one, with no firm foundation to 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 not have the necessary equipment or knowledge to create a new paradigm. A complete scientific revolution, then, is relatively rare. But each crisis does “loosen” the rules and stereotypes of the paradigm it takes place in.
There are two important things to note in this passage. First, Kuhn explains that though not every anomaly leads to a crisis, each new surprise does chip away (even subtly) at scientists’ belief in their paradigm. And secondly, Kuhn’s use of this Albert Einstein quotation—in which Einstein is almost despairing—makes clear just how much an anomaly affects the personal lives of the people who are forced to reckon with it.
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Moreover, as Kuhn insists, a true paradigm shift is not cumulative; instead, it requires scientists to go back to basics. To illustrate this point, Kuhn uses the idea of the Rorschach test (though he does not call it by this name). If in the old paradigm, scientists looked at a picture and saw a bird, now they have rotated the paper—and so they see an antelope.
This is one of the most useful examples Kuhn gives for understanding what a paradigm shift is: not just a change of rules, but a change of worldview and vantage point. However, Kuhn points out that while the bird/antelope drawing is reversible, paradigm shifts are permanent. Scientists cannot see the old world in the old way once they have seen it in a new light.
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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 to create a new paradigm. However, Kuhn notes that it is more difficult to describe this process purely with historical fact; here, he admits that he is conjecturing more than he was in other parts of the book.
Extraordinary science is what the famous figures of science (like Isaac Newton or Galileo) practice; it’s what creates new paradigms, and sometimes even new disciplines. In this passage, Kuhn also highlights his own personhood and subjectivity, admitting his lack of knowledge and thereby modeling such a process for the scientists he writes about.
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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 step, as practiced by Copernicus and Einstein, is to isolate the anomaly and make it seem clearer and more out of place than it did initially—to “localize and define” what is actually differing from the paradigm’s expectations. 
Paradigm shifts are personally and professionally momentous, so anyone practicing extraordinary science needs to justify why such a shift must happen. In Copernicus’s case, for example, that meant moving focus away from issues with the calendar and instead reevaluating the entire model of outer space. 
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Most importantly, Kuhn believes that extraordinary science often goes hand-in-hand with new philosophical thought (much of which comes out of the humanities). For example, Einstein’s theory of relativity happened alongside a sea change in moral and social theory; it is not a coincidence, Kuhn writes, that “thought experiments” are a fundamental part of new paradigms.
If extraordinary science always involves deep-seated, metaphysical questions of belief, it makes sense that spiritual, religious and philosophical change would accompany paradigm change. Einstein’s mathematical relativity thus went along with new theories in moral philosophy and with new movements in art focused on playing with viewers’ perceptions.
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Kuhn does not claim to understand how a person can eventually arrive at the beginnings of a new paradigm—how such an idea “emerges all at once, sometimes in the middle of the night.” But he does note that such people are usually very young or very new to the field, and thus less indoctrinated into a given paradigm’s rules and expectations.
This is an important passage for several reasons: first, Kuhn is again calling attention to scientists as humans. Second, he emphasizes that because scientific communities are so successful at teaching their doctrines, extraordinary science can usually only come from someone outside the field. And finally, Kuhn creates a temporal gap: normal science is routine and happens over a long time, whereas extraordinary science is dramatic and instantaneous—the latter emerges “all at once,” like a sudden flash of inspiration.
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