Paradigm shift 101

You say you want a revolution? Well, you know... We all want to change the world. But few scientific ideas fit Thomas Kuhn’s original definition of a paradigm shift.

Thomas Kuhn's The Structure of Scientific Revolutions covers science prior to 1962, but what about later transformations in science? In this column, we take a look at recent turning points in science history. This month, Diana Crow breaks down the book that started it all.

The term 'paradigm shift' can refer to almost anything. A quick Google news search on the term turned up pieces on the fall of traditional 'Oscar Bait', Catholic church doctrine, and Canadian prime minister Justin Trudeau.

Few of these alleged paradigm shifts hark back to the term’s origin as a synonym for scientific revolution, which dates back to a 1962 book called The Structure of Scientific Revolutions. In it, physicist-turned-philosopher Thomas Kuhn argues that science progresses a series of ideological struggles between rival scientific paradigms.

His ideas were initially controversial. In the 1950s, the prevailing attitude (at least, in public) was that science always moved forward. It made progress, and scientific progress was usually depicted as a good thing. Changes in scientific consensus were supposed to be driven by reason and evidence alone. And above all, science was supposed to objective and perfectly rational.

Kuhn introduced the idea of paradigm shifts, triggering one within his own discipline: history and philosophy of science.   davi.trip/Wikimedia Commons . (CC-BY-A-SA-4.0)

Kuhn introduced the idea of paradigm shifts, triggering one within his own discipline: history and philosophy of science. davi.trip/Wikimedia Commons. (CC-BY-A-SA-4.0)

Enter Kuhn, writing that emotions drive science. In Structure, Kuhn stressed that evidence and logic are crucial for testing ideas. However, he also argued that individuals’ feelings decide which ideas get tested in the first place. Successful paradigms’ earliest champions often collect data based on hunches. Even more damningly, Kuhn claimed that practitioners of 'normal science' sometimes sweep observations that didn’t fit with current consensus paradigms under the rug — or, at least, set weird findings aside for later re-evaluation.

Some critics misread Kuhn’s position as anti-science or anti-evidence, despite his repeated emphasis on the importance of empirical data. But to other readers, putting scientists’ wonderment and puzzle-solving impulses centre-stage rang true. By the end of the decade, the book had become a massive bestseller.

Today, the phrase scientific revolution has a glamorous rebel gleam to it, and paradigm shift has become popular as a grant proposal buzzword. It turns up everywhere, from startups’ press releases to scientific conferences to self-help books. But do all these claimants to the title of 'Revolutionary Paradigm' live up to the criteria Kuhn laid out?

Not really. In true paradigm shifts, people give up their fundamental assumptions in favour of new ones. Much like political revolutions, scientific revolutions are marked by bitter disputes, fierce resistance, and total upheaval. That last bit is the one people seem to forget. As a science journalist, I frequently hear researchers using Kuhn’s terms as smarter-sounding synonyms for mind-blowing.

Still, some ideas have much stronger claims to revolutionary paradigm status than others.

In this column, we'll put a few alleged paradigm shifts to the test. To do that we’ll comb through past papers and essays, and we’ll ask science historians, science writers, and scientists themselves how well these recent shifts match Kuhn’s descriptions. Along the way, we’ll learn about the recent histories of scientific fields and where these fields might be headed. But before we get into all that, we thought it would be helpful to break down Kuhn’s ideas in more detail:

What is a paradigm anyway?

The word paradigm has always been frustratingly nebulous. Kuhn himself didn’t even seem to use it consistently. In 1965, linguist and philosopher Margaret Masterman identified 21 distinct uses of the word paradigm within Kuhn’s book. In some passages, paradigm seemed to refer to a set of assumptions shared by members of a scientific community. In others, it implied techniques or types of experimental questions. And in still others, paradigms appeared to be exemplar papers and experiments that set the standard for a particular field (later Kuhn reluctantly admitted that this is the one he preferred).

Like Masterman, we would argue that what a paradigm does is more relevant than whether it’s a theorem or a technique or something completely intangible. To count as a paradigm (in this column), the scientific whatsit must:

  • Answer questions that other theories and assumptions fail to answer

  • Provoke new questions

  • Enable further experiments or research

The Copernican Revolution was a scientific revolution about the revolution of planets. This diagram from Nicolaus Copernicus' "De revolutionibus orbium coelestium" shows the sun at the center.   Wikimedia Commons  (public domain)

The Copernican Revolution was a scientific revolution about the revolution of planets. This diagram from Nicolaus Copernicus' "De revolutionibus orbium coelestium" shows the sun at the center. Wikimedia Commons (public domain)

In other words, paradigms have to be expansive enough for an entire discipline’s worth of scientists to operate under them. Establishing one previously unknown fact, however interesting, is not enough. Paradigms carry the weight of worldviews, and convincing people to set one aside (as a paradigm shift asks you to do) is seldom easy. However, discarding an entire scientific framework is precisely what happens in a proper Kuhnian paradigm shift.

Start the revolution without me

Not all paradigms lead to paradigm shifts. Many ideas spend decades waiting in the wings, and some paradigms never manage to unseat their predecessor. Others end up being flat-out wrong. When a new paradigm does manage to topple and replace its predecessor, it tends to be a tumultuous event, at least in Kuhn’s account. Data collected under the older paradigm takes on new meaning. Scientific disciplines have to be redefined. Textbooks get rewritten.

Truly revolutionary paradigms tend to get a lot of pushback when they debut. However, successful revolutionary paradigms tend to come into their own at moments when the reigning paradigm has already been weakened by unexplained or contradictory findings.  

In this column, we want to explore science’s more recent big ideas and ask whether they fit Kuhn’s description of a paradigm shift. We’ll judge based on whether the paradigm candidates do the following:

  • Challenge or replace a paradigm in crisis

  • Attract and rally supporters within scientific community

  • Hold up after new experimental data comes in

  • Transform or redefine a scientific subdiscipline

Kuhn wrote that he couldn’t think of many cases where two paradigms coexisted within a scientific field peacefully, but then again, he developed his ideas based on Enlightenment physics. This column will be focusing on paradigms that rose to power after 1962, so we may end up seeing different patterns.

At the end of the day, scientific revolutions are defined by changes to scientific communities. No single scientist can declare their own work to be a paradigm shift; a sizeable number of researchers have to come to a new consensus and alter the way they do science because of it.

So let’s start with a big one: the land beneath our feet is not as solid as we once thought, and may, in fact, be moving.