The Structure of Scientific Revolutions
(1962)
Thomas Kuhn


Thomas Kuhn was a graduate student in theoretical physics at Harvard, close to finishing his dissertation for his PhD, when he was asked to teach an experimental college course on science for non-scientists. It was his first real taste of the history of science, and it changed his life.

To his surprise, the course altered some of his basic assumptions about science, and the result was a big shift in his career plans from physics to the history and then philosophy of science. In his mid-30s he wrote a book on Copernicus, and five years later produced The Structure of Scientific Revolutions. A monograph of only 170 pages, the book sold over a million copies, was translated into 24 languages, and became one of the most cited works of all time in both the natural and social sciences. Its success was highly unusual for an academic work, and was a shock to Kuhn himself. 

The work is shortish because it was originally composed with the aim of being a long article in the Encylopedia of Unified Science. Once published, this article was expanded into a separate book. This limitation turned out to be a blessing, as he was prevented from going into lengthy and difficult scientific detail, making the book just readable for the layman.

Why has the Structure made such a huge impact? If its message has been restricted to science itself the work would still be very important, but it is the generic idea of ‘paradigms’, in which one world view replaces another, that has been considered valuable across so many areas of knowledge. Indeed, at several points in the book Kuhn touches on the fact that paradigms exist not only in science, but are the natural human way of comprehending the world. The roots of the book lay in an experience Kuhn had reading Aristotle, when he realised that Aristotle’s laws of motion were not just ‘bad Newton’, but a completely different way of seeing the world.

Science is made by scientists

Kuhn starts by saying that the traditional textbook accounts of the development of science can no more tell us about reality than a tourist brochure can tell us about a nation’s culture. The textbooks present an incremental accumulation of facts, and describe theories borne out by successful experiments that lead to increasing amounts of knowledge. But does science really proceed in such a neat way?

Kuhn sought a less arrogant and more open view that understood scientific advance not as isolated individuals making great discoveries, but in terms of the scientific community and the intellectual environment of the day allowing (or disallowing) the reinterpretation of existing data. Central to his argument is that scientists do not proceed by simply describing how nature works, but rather work within paradigms of understanding which, once they turn out to be deficient in explaining phenomena, are replaced by new ones. He defines paradigms as “universally recognized scientific achievements that for a time provide model problems and solutions to a community of practitioners”.

Why is this view of scientific progress different? The conventional view of science is: ‘here are the facts’ about the world, and ‘here we are’ (the scientists) uncovering them. But facts do not exist without an observer, which means that the interests of the observer are all-important to what constitutes current science. Moreover, the progress of science is only partly about the discovery of the new; it concerns changing how we see what we already thought we knew. X-rays, Kuhn notes, “were greeted not only with surprise but with shock”, because they did not fall into any existing theory. When a paradigm is replaced by another one, the world itself seems to change: “What were ducks in the scientist’s world before the revolution are rabbits afterwards.”

One of Kuhn’s startling insights is that paradigms can have integrity, providing most of the answers to most of the questions asked of them in their day, and yet also be fundamentally wrong. For a long time the earth-centred view seemed to be a good explanation of cosmology, satisfying most people, until the various anomalies within the model became too obvious to ignore, and a sun-centred paradigm became accepted. But the human affinity for certainty means such revolutions are always resisted. Real discovery begins with recognition of anomalies, or nature acting in a way that it is not meant to. Scientists don’t know what to do with these facts, and so they are not ‘scientific’ until they have found a home in an existing theory.

A paradigm starts to crumble when there is a heightened insecurity about the capacity of the paradigm to solve the puzzles it has set for itself. Practitioners keep getting the ‘wrong’ answers. The paradigm is in crisis mode, and it is at such points that breakthroughs to a new paradigm are possible e.g. Copernican astronomy, Einstein’s special theory of relativity.

Kuhn observes that in the early stages of a new discipline there is usually no established paradigm, only competing views trying to explain some aspect of nature. Each of these views may be following established scientific method, but only one view becomes the accepted way of seeing. This is not because everyone comes to agree on the facts, but because it is easier to work with a single paradigm; human psychology comes much more into play than we would like to admit. Science, Kuhn notes, does not progress coldly and clinically of its own volition, but is made by scientists.

Normal and revolutionary science

Kuhn makes a distinction between ‘normal’ science, and the type of scientific thinking or research which can cause revolutions in how we see the world.

Normal science is based on the assumption “that the scientific community knows what the world is like”, and furthermore, “Much of the success of the enterprise derives from the community’s willingness to defend that assumption, if necessary at considerable cost.” Normal science tends to suppress anomalous facts because they are a road block in a pre-committed theoretical path. Kuhn defines these novelties or anomalies within an existing paradigm as a “violation of expectation”. The response to anomalies is hardly ever to renounce the existing paradigm; it is to keep working within it to see what went wrong. Only a tiny minority of scientists can truly ‘think outside the box’ and look at nature in a fresh way.

The basis of joining any scientific community is the study of its paradigm, and the vast majority of scientists will spend their lives working on things within that paradigm: smaller puzzles that need to be solved, or incremental research. Or, they work to produce findings that can bring nature and the theory/paradigm closer together, like many scientists did in the wake of Newton’s Principia. Normal science is “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 sets of phenomena; indeed those that will not fit the box are often not seen at all.” The problem is that when an unexpected novelty appears, scientists will either reject it out of hand as a ‘mistake’ or put it down to a failure of method to prove what you were expecting. Thus the aim of normal science is not to find something new, but to make the existing paradigm more precise, to bring nature into accord perfectly with the theory.

Scientific revolutions, on the other hand, Kuhn says are the “tradition shattering complements to the tradition-bound activity of normal science”. New theories are not simply new facts, but wholesale changes in how we see those facts.  This in turn leads to the reconstruction of theories, which is “an intrinsically revolutionary process that is seldom completed by a single man and never overnight”.

Two different worlds:  the incommensurability of paradigms

Since paradigm change is not a rational process, but rather a gulf between what different parties see, paradigms do not compete. They cannot agree on the methodology to tackle problems, or even on the language needed to describe them; the paradigms are ‘incommensurable’, Kuhn says, because they have no common standard by which to judge each other.

Neither is it a case of each paradigm being closer or further away from an objective truth about the universe. The very essence of paradigms is that they are about the people who make and propose them, and each effectively inhabits a different world. Kuhn quotes Max Planck:

“[A] new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”

Indeed, it took over a century following his death for Copernicus’ views to really catch on, and Newton’s ideas were not generally accepted for over 50 years after he published the Prinicipia. Kuhn concludes that, “The transfer of allegiance from paradigm to paradigm is a conversion experience that cannot be forced.” But scientific communities do eventually catch on, and begin the process of ‘proving’ what the new paradigm suggests must be right.

Final comments

The Structure was shocking in its suggestion that science does not take humanity on a neat linear path towards some objective truth about the reality of the world via the accumulation of empirical observations (what can be called the Enlightenment view), but is in fact a human creation. If science is the attempt to make our theories fit nature, then it is human nature that we have to contend with first.

We like to weave advances or changes in scientific understanding into a grand story of progress, but Kuhn’s implication is that science has no aim, but simply adapts its explanations to reality as best it can. In the second edition of the book, Kuhn made it clear that he wasn’t a relativist, and that he believed in scientific progress. However, he also made clear that science was like the theory of evolution: it evolves from something simpler, but you couldn’t say that it has a final end or direction to it.

A common interpretation of Kuhn is that paradigms are ‘bad’ and give people a blinkered view, when they should be always questioning the paradigm that underlies their discipline. In fact, Kuhn noted that the acquisition of a paradigm is a sign that a field has matured into something real, because it at least has a set of rules that the practitioners can agree on. Paradigms are neither positive nor negative, but simply give us a way of seeing the world. The real value lies in seeing paradigms objectively, and admitting the possibility that our truths may be just assumptions.


Source: Philosophy Classics: Thinking, Being, Acting, Seeing, Profound Insights and Powerful Thinking from Fifty Key Books by Tom Butler-Bowdon (London & Boston: Nicholas Brealey. 

Thomas S Kuhn

Born in 1922, Kuhn’s father was a hydraulic engineer turned investment consultant, and his mother was an editor. He grew up near New York City and attended various private schools before being accepted into Harvard University. 

After graduating, Kuhn joined the war effort, working in radar in the US and Europe, before returning to Harvard to do graduate work in physics. He also took philosophy courses on the side, and considered switching to philosophy, but felt it was too late to begin in this field. At 30 he began teaching history of science, and his steep learning curve in a new field meant he had little time for producing his own work. As a result, the Structure was a decade in the making. Kuhn couldn’t get tenure at Harvard, so took an assistant professorship at the University of California, Berkeley. In 1964, Princeton offered him a full professorial role in the history and philosophy of science, where he stayed for 15 years before spending the final stage of his career at MIT (1979-91).  

 Kuhn’s first book was The Copernican Revolution: Planetary Astronomy in the Development of Western Thought (1957). He also wrote Sources for the History of Quantum Physics (1967). In the years following publication of the Structure Kuhn revisited and clarified some of its concepts (see The Road Since Structure: Philosophical Essays, 1970-1993, which includes an Autobiographical Interview with Kuhn). He died in 1996.