, , ,

Thomas Kuhn (1922 – 1996) was an American philosopher of science who introduced the term “paradigm shift”. The success of the paradigm… is at the start largely a promise of success.

Thomas Kuhn

Thomas Kuhn, philosopher of science

Sources for quotations: WikiQuotes, EGS, GoodReads, BrainyQuotes, TodayInScience,

Quotations from Thomas Kuhn

“Normal science” – the activity in which most scientists inevitably spend most all their time, is predicated on the assumption that the scientific community knows what the world is like. Normal science, often suppresses fundamental novelties because they are necessarily subversive of its basic commitments. As a puzzle-solving activity, normal science not aim at novelties of fact or theory and, when successful, finds none.

“Normal science” means research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice

And even when the apparatus exists, novelty ordinarily emerges only for the man who, knowing with precision what he should expect, is able to recognize that something has gone wrong.

Men whose research is based on shared paradigms are committed to the same rules and standards for scientific practice. That commitment and the apparent consensus it produces are prerequisites for normal science, i.e., for the genesis and continuation of a particular research tradition.

Scientists work from models acquired through education and through subsequent exposure to the literature often without quite knowing or needing to know what characteristics have given these models the status of community paradigms

If these out-of date beliefs are to be called myths, then myths can be produced by the same sorts of methods and held for the same sorts of reasons that now lead to scientific knowledge.

Observation and experience can and must drastically restrict the range of admissible scientific belief, else there would be no science. But they cannot alone determine a particular body of such belief. An apparently arbitrary element, compounded of personal and historical accident, is always a formative ingredient of the beliefs espoused by a given scientific community at a given time.

Perhaps science does not develop by the accumulation of individual discoveries and inventions.

Gravity, interpreted as an innate attraction between every pair of particles of matter, was an occult quality in the same sense as the scholastics’ “tendency to fall” had been.

Its assimilation requires the reconstruction of prior theory and re-evaluation of prior fact, an intrinsically revolutionary process that is seldom completed a single man and never overnight.

Newton’s three laws of motion are less a product of novel experiments than of the attempt to reinterpret well-known observations in terms of motions and interactions of primary neutral corpuscles.

Unable either to practice science without the Principia or to make that work conform to the corpuscular standards of the seventeenth century, scientists gradually accepted the view that gravity was indeed innate.

To turn Karl [Popper]’s view on its head, it is precisely the abandonment of critical discourse that marks the transition of science. Once a field has made the transition, critical discourse recurs only at moments of crisis when the bases of the field are again in jeopardy. Only when they must choose between competing theories do scientists behave like philosophers.

Somehow, the practice of astronomy, physics, chemistry or biology normally fails to evoke the controversies over fundamentals that today seem endemic among, say, psychologists or sociologists. Attempting to discover the source of that difference led me to recognize the role in scientific research of what I have since called “paradigms.” These I take to be universally recognized scientific achievements that for a time provide model problems and solutions for a community of practitioners.

Normal science, the puzzle-solving activity we have just examined, is a highly cumulative enterprise, eminently successful in its aim, the steady extension of the scope and precision of scientific knowledge.

[The] most fundamental aspect of the incommensurability of competing paradigms… is that “the proponents of competing paradigms practice their trades in different worlds.

In a sense that I am unable to explicate further, the proponents of competing paradigms practice their trades in different worlds. One contains constrained bodies that fall slowly, the other pendulums that repeat their motions again and again. In one, solutions are compounds, in the other mixtures. One is embedded in a flat, the other in a curved, matrix of space. Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction. Again, that is not to say that they can see anything they please. Both are looking at the world, and what they look at has not changed. But in some areas they see different things, and they see them in different relations one to the other. That is why a law that cannot even be demonstrated to one group of scientists may occasionally seem intuitively obvious to another.

As in political revolutions, so in paradigm choice—there is no standard higher than the assent of the relevant community… this issue of paradigm choice can never be unequivocally settled by logic and experiment alone.

Concerned to reconstruct past ideas, historians must approach the generation that held them as the anthropologist approaches an alien culture. They must, that is, be prepared at the start to find that natives speak a different language and map experience into different categories from those they themselves bring from home. And they must take as their object the discovery of those categories and the assimilation of the corresponding language.

Later scientific theories are better than earlier ones for solving puzzles in the often quite different environments to which they are applied. That is not a relativist’s position, and it displays the sense in which I am a convinced believer in scientific progress.

Scientific development depends in part on a process of non-incremental or revolutionary change. Some revolutions are large, like those associated with the names of Copernicus, Newton, or Darwin, but most are much smaller, like the discovery of oxygen or the planet Uranus. The usual prelude to changes of this sort is, I believed, the awareness of anomaly, of an occurrence or set of occurrences that does not fit existing ways of ordering phenomena. The changes that result therefore require ‘putting on a different kind of thinking-cap’, one that renders the anomalous lawlike but that, in the process, also transforms the order exhibited by some other phenomena, previously unproblematic.

The historian of science may be tempted to claim that when paradigms change, the world itself changes with them. Led by a new paradigm, scientists adopt new instruments and look in new places. even more important, during revolutions, scientists see new and different things when looking with familiar instruments in places they have looked before. It is rather as if the professional community had been suddenly transported to another planet where familiar objects are seen in a different light and are joined by unfamiliar ones as well.

The success of the paradigm… is at the start largely a promise of success … Normal science consists in the actualization of that promise… Mopping up operations are what engage most scientists throughout their careers. They constitute what I am here calling normal science… 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. Nor do scientists normally aim to invent new theories, and they are often intolerant of those invented by others.

We may… have to relinquish the notion, explicit or implicit, that changes of paradigm carry scientists and those who learn from them closer and closer to the truth… The developmental process described in this essay has been a process of evolution from primitive beginnings—a process whose successive stages are characterized by an increasingly detailed and refined understanding of nature. But nothing that has been or will be said makes it a process of evolution toward anything.

COMMENTS on Quotations from Thomas Kuhn

But nothing that has been or will be said makes it a process of evolution toward anything. Kuhn’s statement seems to contradict the great quests which self-conscious scientists pursue. How does reality work? Are there laws of behavior which can be discovered? If there are laws, how can we discover them? And of course scientists seek answers to the basic philosophical questions – Where did we and our world come from? What is our destiny? What should I do now?

Kuhn mentions evolution as not having a goal, but of course it always has a non-conscious immediate goal, to survive. Not a mentally self-conscious goal, as that is only available to humans some of the time, but an instantaneous goal; a drop of water falling from the sky is at every instant responding to the forces acting on it. The goal is always to be responding to the forces of the moment, and in a positive feedback system, like the evolution of life forms. That means evolution proceeds, at least until something terminates it.

The success of the paradigm… is at the start largely a promise of success … Normal science consists in the actualization of that promise… Mopping up operations are what engage most scientists throughout their careers. That statement implies that very few people calling themselves scientists are doing the creative work of seeking answers outside of their specialized community-imposed box. Because of this stovepiping of parallel but related ideas and the consequent narrowness of individual research, here exists a tremendous potential for finding underlying basic ideas. It’s a form of convergent evolution which can be found by a google search identifying the different vocabulary in different fields covering the same basic idea. Once a single convergent pair is found it becomes more likely that there will be others in other stovepiped research fields and in life forms. Wherever convergence of separate cyclic entities is observed there will be a definable underlying process. The power of finding these convergent ideas is that, because of stovepiping, there are probably other fields where the idea hasn’t been discovered yet and which would instantly benefit from the idea being applied. This convergent evolution of ideas concept needs a specialized search term so that it may be easily googled, and it needs a university-level department to specialize in these types of universe-wide searches. 

. . .