What Was the “Paradigm Shift”?

did you encounter your first paradigm shift? Not the phenomenon itself, but the
term? Perhaps at an airport bookstore, where bestselling authors of books with
titles like Change Your Paradigm, Change
Your Life
and The 15 Commitments of
Conscious Leadership: A New Paradigm for Sustainable Success
use it
more or less as a synonym for “game changer.” Or maybe on the taps of Paradigm
Shift Brewery, a
craft brewery located in Massilon, Ohio. The goods and services you can
purchase with “paradigm” in their name include coffee and crypto, sneakers,
and health care management. The corporate website for perhaps the best-known
Paradigm, a high-end Canadian speaker company, explains that the founders
“decided to, eh-hem, change the
prevailing industry paradigm.”

language of paradigms and paradigm shifts is ubiquitous except among the people
most familiar with its source: historians and philosophers of science. Once
upon a time—let’s say the late 1960s—a reference to “paradigm shifts” primarily
signaled knowledge of Thomas Kuhn’s historicist approach to the philosophy of
science. Kuhn’s 1962 classic, The Structure of Scientific
transformed our understanding of scientific change and has
become a foundational text for historians, philosophers, and social studies of
science. It is nonetheless unusual these days for anyone who studies science
professionally to invoke the term “paradigm shift.” The concept has become
completely unmoored from the term.

The Structure of Scientific
other words, is one of those books that everybody knows but doesn’t read, or
reads once and shelves. On rereading my copy, neglected since a first-year
graduate seminar in the history of science over 25 years ago, I was struck by
Kuhn’s insistence on the power of historical research to puncture idealized
claims of scientific progress. Paradigms and normal science? Sure. But the
truly radical idea here is that outsiders—in this case, historians—can offer
better insight into the inner workings of a profession than the practitioners

exactly, is a paradigm shift? In Structure,
Kuhn defines a scientific paradigm through its relation to what he calls
“normal science.” A mature scientific community, one that is relatively secure
in its methods, intellectual assumptions, and choice of problems, is operating
in a period of “normal science.” Collectively, those rules and standards for
scientific research constitute “shared paradigms.” These shared paradigms lay a
path for scientific communities to work efficiently, allowing individual
scientists to focus on the “mop-up work” of collecting data and solving puzzles
suggested by the operating paradigm. 

time, however, this routine puzzle-solving work will generate “anomalies” that
violate the expectations established by the paradigm. At first, scientists who
encounter such anomalies tend to assume that they have made some sort of
experimental error. Those who insist on the correctness of their divergent
findings may be considered cranks. An abundance of anomalies, once acknowledged
by the community, throws that community into crisis. When the crisis cannot be
resolved by tweaking the existing paradigm, a competing interpretation that casts
the data in entirely new ways may gain ascendance. This switching of the
paradigms constitutes a scientific revolution. Scientists might reject
phlogiston in favor of oxygen, for example, or embrace heliocentrism after
centuries of Aristotelianism. 

famously described these competing paradigms as “incommensurable.” A belief in
phlogiston is simply incompatible with the existence of oxygen. You cannot
simultaneously believe that the sun orbits the Earth and that the Earth orbits
the sun. Drawing on mid-twentieth-century psychology and theories of mind, Kuhn
compared these shifts in attitudes to gestalt shifts—the kind of change in
perspective that turns an image of a rabbit
into a duck. In perhaps the book’s most controversial chapter, Kuhn argued
that changing paradigms changes nature itself, or at least the way scientists
perceive it. Change a paradigm, change the world. 

in broad outlines, is the gist of the book’s argument. The text itself is
fairly technical, as Kuhn, who trained as a theoretical physicist, assumes his
readers will have a working knowledge not only of key concepts in eighteenth-,
nineteenth-, and twentieth-century physics but also of live debates
in mid-twentieth-century philosophy of science. Accordingly, much of
the initial critical response came from specialists focused on inconsistencies
in Kuhn’s own thinking. One early review, for instance, cataloged at least 22 different
ways that Kuhn uses the term “paradigm.” Other readers noted that Kuhn barely
bothered to define these “scientific communities” whose assumptions and norms
define the paradigms.

generously acknowledged the legitimacy of both of these critiques in a
postscript published in the 1969 edition of the book, but he held his ground on
what he saw as the book’s fundamental point: Science does not progress through
the accumulation of incremental facts, theories, and methods. When science does
progress, it does not necessarily progress in a particular direction that
aligns it more closely with nature. Instead, science advances through ruptures
that require that scientists reject the past. As he argued in the original
edition: “Cumulative acquisition of unanticipated novelties proves to be an
almost non-existent exception to the rule of scientific development. The man
who takes historic fact seriously must suspect that science does not tend
toward the ideal that our image of its cumulativeness has suggested. Perhaps it
is another sort of enterprise.”

Kuhn did not specify what kind of enterprise it might be instead.

can gain some clues from the context in which
Structure was written. This requires a journey back to the early
1950s, when a young Kuhn was teaching the history of science at Harvard. Kuhn’s
tenure at Harvard coincided with the waning years of the presidency of James B.
Conant, a chemist who had long left the lab in favor of scientific and
political administration. During World War II, Conant had chaired the National
Defense Research Committee and advised President Harry Truman on the use of the
atomic bomb. About halfway through Kuhn’s tenure at Harvard, Conant retired to
serve as the high commissioner for occupied Germany.

astonishingly productive Conant also wrote several books on the future of
higher education in the United States. These books repeatedly turned to a theme
that Conant and many scientists of his generation saw as one of the most
pressing questions facing the U.S. in the Cold War: What was the role
of science, and specifically science education, in a democracy? National
defense required that political authorities and scientists work closely
together, yet many also feared the rise of a technocracy or that science might
bend to political authority. Having examined the recent history of science in
Nazi Germany, the Soviet Union, and the U.S., Conant sought a pedagogical
strategy that could cultivate a new generation of curious scientists and
instill respect for science among nonscientists but that would also carefully
calibrate citizens’ questioning of authority.

solution was historical method. Shortly after the war ended, Conant began
teaching a new course on the history and philosophy of science for Harvard undergraduates.
In a turn that was unusual for courses in the history of science at the time,
Conant covered scientific wrong turns and dead ends, including alchemy and
theories of spontaneous generation. Kuhn’s experience of teaching a version of
this course transformed his understanding of the history and philosophy of

crucial context explains the book’s otherwise peculiar obsession with
scientific textbooks. The problem with textbooks, as Kuhn repeatedly explains,
echoing Conant, is that they obscure scientific debate and prior explanations in
the name of inducting students into the reigning understanding of how the world
works—that is, a scientific paradigm. These textbooks, he claims, have to be
“rewritten” when normal science changes, because they “refer only to that part
of the work of past scientists that can easily be viewed as contributions to
the statement and solution of the texts’ paradigm problems.”

acknowledges that there might be sound pedagogical reasons for this, but he
nonetheless remains clearly troubled by the fact that most textbook stories
about the development of science—at least the kind presented in 1950s
textbooks—were simply not true. Again echoing Conant, Kuhn particularly
objected to the fact that students had no access to their own facts that they
could use to test the relationship between theory and evidence: “Science
students accept theories on the authority of teacher and text, not because of
evidence.” Students, in other words, are at the mercy of authority figures, and
these authority figures were, via their textbooks, feeding them lies.

critiques of scientists’ own telling of history, particularly as tendered in
textbooks, is not subtle. Historically accurate accounts of how science
develops, full of messy data, theoretical dead ends, and disproven assumptions,
Kuhn suggested, posed a threat to scientific authority by elevating “human
idiosyncrasy, error, and confusion.” At one point, Kuhn explicitly compares scientists’
approach to rewriting history to the one depicted in George Orwell’s 1984, albeit with the caveat that
scientific paradigms derive their authority from the consensus of the
scientific community rather than political fiat.

modern readers, this sounds like an attack on science, or at least on their
textbooks. But this was 1962, just five years after the Soviet Union launched Sputnik, the first artificial satellite.
The Soviet Union’s apparent lead in the space race generated a national panic
about the state of science education in the U.S. One consequence was the
passage of the National Defense Education Act of 1958, which, among other
things, provided millions of dollars to redesign high school science
curricula, particularly in physics, mathematics, biology, and the earth
sciences. In keeping with Conant’s theories of education and democracy, these
experimental science curricula typically incorporated at least moderately
accurate historical accounts of scientific change. They also encouraged
students and teachers alike to embrace the uncertainty produced through
experimentation, both as a way to prepare future scientists for the realities
of scientific work and to discourage unthinking allegiance to authority.

1962, then, few university scientists, many of whom were themselves engaged in creating
the new curricula, took offense at Kuhn’s strident commentary on science
textbooks. Kuhn’s list of the people who propagate falsehoods about science—textbook
authors, popularizers, and philosophers—doesn’t even include scientists (though
of course many scientists engage in this kind of work). As more time passed
from the date of publication, however, this context was lost. While many
scientists found Kuhn’s model of scientific change useful, they bristled at his
characterization of the scientific community. No one, it’s fair to say, wants to be
compared to the textbook writers in 1984.

claimed, both in 1962 and for the rest of his career, that he had not intended
any of this as an attack on the scientific enterprise itself. For Kuhn, the
entire point of Structure was to elucidate
what he and many scientists of his generation saw as science’s distinctive
ability to build cumulative knowledge. “Why,” as Kuhn wrote, “is progress a
perquisite reserved almost exclusively for the activities we call science?”
Part of the answer flows from the practices of normal science, which free
scientists up to focus on routine problem-solving. But Kuhn argued that even the
disruption of paradigm shifts generally strengthens, rather than weakens,
scientists’ ability to solve new problems, for the straightforward reason that
scientific communities prefer practices that “ensure the continuing growth of
the assembled data that [they] can treat with precision and detail.”

Kuhn, this definition of scientific progress, with its dedication to routine
problem-solving and fidelity to the actual history of science, represented a
major step forward from pedagogical fairy tales about science as a process of
constant discovery. But Kuhn himself acknowledged one critical way in which his
account of scientific progress diverged from common understanding: It had
nothing to do with truth. Instead of thinking of science as a process that
inevitably draws closer to natural reality, Kuhn suggested that we treat scientific
change as an evolutionary process, similar to natural selection, in which
various paradigms compete for community advantage.

charged relativism. If science had no inherent orientation toward nature or
truth, then facts could be whatever a scientific community agreed them to be. Kuhn
deflected this critique by pointing to the supposedly distinctive characteristics
of the scientific communities that he hadn’t actually defined. In the 1969 afterword, he called for more studies of scientific communities. Given the
works he cited, he likely had in mind projects like sociologist Diana Crane’s
notion of an “invisible college” or entrepreneur Eugene Garfield’s approach to
citation analysis, each of which highlighted network effects within recognized
communities of experts.

the mid-1980s, a new generation of historians, sociologists, and
anthropologists of science brought a more critical lens to scientific power.
They incorporated ideas about race, sex, gender, national and historical
context, and, most importantly, power into their analyses of what drove
scientific communities to embrace some theories and reject others. Defenders of
science took to calling this approach “Kuhnian,” to Kuhn’s everlasting chagrin.
The charge was ridiculous then and ridiculous now: Structure’s approach to its topic is in many ways absurdly
intellectually conservative, given that it excludes the natural and social
sciences and any discussion of technology or, as he puts it, “external social,
economic, and intellectual conditions in the development of the sciences.” It
is blithely Eurocentric, confidently asserting that “only the civilizations
that descend from Hellenic Greece have possessed more than the most rudimentary
science.” In Structure, Kuhn sought
to explain what made science tick, not to critique science’s cultural power.

Kuhn’s fiercest critics were right about one thing: Kuhn didn’t trust
scientists to tell their own stories. Until Structure,
scientists and their historians seemed natural allies, jointly committed to sharing
the story of scientific progress. Structure
shattered this notion, suggesting that social scientists, with their
attention to empirical data, were better situated to explain not only the past but also the future of science. To the extent that scientists resisted Kuhn’s
interpretation, they resented his incursion on what they perceived to be their
own territory—a dynamic familiar to anyone who’s encountered, say, economists’
response to economic history or teaching bans on the 1619 Project.

argued that a warts-and-all approach to history could uphold and even enhance
scientific authority by showing science’s remarkable power to progress despite
periodic changes in perspective. It’s a complex view of history that is
incommensurable with stories of uncomplicated discovery and scientific heroism.
For the culture at large, Structure’s
greatest contribution has been linguistic—the notion of “paradigm change” as a
synonym for “thinking outside the box.” But read in 2024, in light of the
current history wars, the real revolution at the heart of Structure was a paradigm shift in scientific narrative. Who gets to
tell the story of a field? And how truthful should they be in their telling?