Scientific revolutions or paradigm shifts

With great thanks to Alan Mason – Deskarati -[Thomas Kuhn, an American academic put forward his ideas in 1962, on what he saw as the true historical development of science in his book, “The Structure of Scientific Revolutions”.

He introduced the idea of “paradigm” to describe a generally accepted model or view of a branch of science which was accepted by the experts and most practitioners in that particular field. The paradigm encompassed the basic theory, various laws, and the logical consequences of that particular view.

Kuhn also examined the nature of major scientific revolutions, which he described as paradigm shifts, a term he did not originally coin, but which has now won general acceptance among professional scientists and philosophers of science. In a paradigm shift the whole model or viewpoint of the specialism undergoes a radical change.]

NORMAL SCIENCE

Kuhn uses the term, “normal science” to describe activity within an existing and accepted paradigm. “Normal science, the activity in which most scientists inevitably spend almost all their time, is based on the assumption that the scientific community knows what the world is like. Normal science, for example, often suppresses fundamental novelties because they are necessarily subversive of its basic commitments.”

Novelties

Nevertheless, the very nature of normal research ensures that novelty shall not be suppressed for very long. Sometimes a normal problem, that ought to be solvable by known procedures, resists all efforts, or a piece of equipment fails to perform in the anticipated manner, revealing an anomaly that cannot, be aligned with professional expectation.

SCIENTIFIC REVOLUTIONS

In these ways, normal science repeatedly goes astray. When the profession cannot evade anomalies undermining the existing tradition a new basis for the practice of science is needed. Those shifts are known as scientific revolutions. They are the tradition-shattering complements to the tradition-bound activity of normal science. The most obvious examples of scientific revolutions are those major turning points associated with the names of Copernicus, Newton, Lavoisier, and Einstein. More clearly than most other episodes in the history of the physical sciences, these display what all scientific revolutions are about.

The most significant scientific revolution, because it was so widely known to people of all kinds, more than any other scientific theory, is the Copernican Revolution. This was the point when the Heliocentric Theory (the sun is at the centre of the solar system) replaced the Geocentric Theory (the earth is at the centre of everything) The latter theory had been in place for more than two millennia, mainly because it seemed like common sense.

A simple table of some of the more important scientific revolutions is given later with an approximate idea of the times in which they occurred.

The Two Paradigms left the Geocentric View, and right the Heliocentric View

From “De Revolutionibus Orbium Coelestium” (On the Revolution of Celestial Bodies)

By Nicholas Copernicus, (shown below)

SOME IMPORTANT SCIENTIFIC REVOLUTIONS OR PARADIGM SHIFTS

TIME

MATHEMATICS, ASTRONOMY, PHYSICS

GEOLOGY, CHEMISTRY,

BIOLOGY, MEDICINE,

Antiquity to 1400s Theory of a Spherical Earth
Early 1500s Heliocentric Theory of Solar System (Copernicus, Brahe, Kepler)
Mid 1600s Corpuscular Theory of Light and Optics (Newton) Theory of Blood Circulation (Harvey)
Mid 1600s Theory of Motion and Mechanics (Newton) Cellular Theory of Biological Structure (Leeuwenhoek, Hooke,)
Mid 1700s Oxygen Theory of Combustion (Lavoisier)
Mid 1700s Theory of Gases, (Boyle, Charles, Cavendish, Lavoisier) Species Concept in Biology (Linnaeus)
Late 1700s Theory of Static Electricity (Franklin) Theory of Gaseous Chemical Elements (Dalton, Lavoisier)
Early 1800s Theory of Heat and Thermodynamics (Rumford, Carnot, Joule,) Theory of Metallic Elements (Davy, )
Early 1800s Theory of Current Electricity and Electro-Chemistry (Galvani, Coulomb, Faraday) Uniformitarian Theory of Geology (Hutton, Lyell) Theory of Evolution by Natural Selection (Darwin, Wallace, Huxley)
Late 1800s Electro-magnetic Wave Theory of Light (Clerk-Maxwell) Periodic Theory of All Elements (Mendeleev) Bacterial Theory of Disease (Koch, Pasteur, )
Late 1800s Quantum Theory of Radiation (Planck) Theory of Recent Ice Ages (Agassiz)
Late 1800s Sub-Atomic Particle Theory of Matter (Thompson)
Early 1900s Theory of General Relativity (Einstein) Isotopic Theory of All Elements (Moseley, Aston) Theory of Genetical Inheritance, (Mendel, De Vries, Bateson)
Early 1900s Theory of Galactic Dimensions (Hubble) Theory of Blood Groups (Landsteiner)
Mid 1900s Theory of Expanding Universe (Hubble) Theory of Continental Drift and Plate Tectonics (Wegener) Theory of DNA Coding (Crick, Watson, Franklin)
Mid 1900s Theory of Gravitational Collapse ( )

Three Characteristics of Scientific Revolutions

(1) The community’s rejection of one time-honored scientific theory in favor of another incompatible with it.

(2) A shift in the problems available for scientific scrutiny and the standards by which solutions should count as admissible or legitimate.

(3) A transformation in scientific imagination on how scientific work was done.

Such changes, together with the controversies that always accompany them, are the defining characteristics of scientific revolutions.

PARADIGM SHIFTS IN PHYSICAL OPTICS

If we trace the scientific knowledge of a group of phenomena backward in time, we find a pattern here illustrated from the history of physical optics.

(1) Today’s physics textbooks tell the student that light is photons, i.e., quantum-mechanical entities that exhibit some characteristics of waves and some of particles. That characterization of light is scarcely half a century old when it was developed by Planck, Einstein, and others early in the 20 C.

(2) Before that, physics texts taught that light was transverse wave motion, a conception rooted in a paradigm that derived from the optical writings of Young and Fresnel in the early nineteenth century. Nor was the wave theory the first to be embraced by almost all practitioners of optical science.

(3) During the eighteenth century the paradigm was provided by Newton’s “Opticks”, which taught that light was material corpuscles. At that time physicists sought evidence, as the early wave theorists had not, of the pressure exerted by light particles hitting solid bodies.

These transformations of the paradigms of physical optics are scientific revolutions, and the successive transition from one paradigm to another via revolution is the usual developmental pattern of mature science.

STATIC ELECTRICITY RESEARCH IN THE 18 CENTURY

In the 18 C there were as many views about electricity as there were electrical experimenters. All their concepts of electricity had something in common; they were derived from a version of the mechanico-corpuscular philosophy, (that is, moving particles), guiding the scientific research of the day.

All the experimenters had produced real scientific theories that had been drawn from experiment and observation. This determined the choice and interpretation of further problems in research. Although most of the experimenters read each other’s works, their theories had no more than a family resemblance. One group regarded attraction and frictional generation as the fundamental electrical phenomena, and repulsion was a secondary effect due to rebounding. More importantly they postponed both discussion and systematic research on Gray’s newly discovered effect, of electrical conduction.

Benjamin Franklin, in Heroic Pose, as He Captures the Electricity of Lightning

Others took attraction and repulsion to be equally elementary aspects of electricity, but they had as much difficulty as the first group in accounting for conduction effects. Those effects, provided the starting point for a third group, which saw electricity as a “fluid” that ran through conductors. This group also had difficulty reconciling its theory with a number of attractive and repulsive effects.

A Paradigm – Electricity as a Fluid

The work of Franklin and his successors produced a theory that accounted for all these effects and provided a subsequent generation of electrical workers with a common paradigm for its research. This was the idea that electricity is a fluid. Led by this belief several workers attempted to bottle it. The fruit of their efforts was the Leyden jar, a device which would never have been produced by exploring nature casually or at random, but which was devised on the basis of theory.

The Leyden Jar As Employed by Franklin

It was independently developed by two investigators in the early 1740’s. Eager to explain a piece of special apparatus, Franklin provided the arguments that made his theory a paradigm, though unable to account for all known cases of electrical repulsion. To be accepted as a paradigm, a theory must seem better than its competitors, but it need not, and never does, explain all the facts with which it can be confronted.

The fluid theory of electricity and the Franklin paradigm suggested which experiments would be worth performing and which would not. The paradigm did the job effectively, because interschool debate ended, and the confidence that they were on the right track encouraged them to undertake more precise and demanding work.

The researchers pursued selected phenomena in detail, designing special equipment for the task and employing it more systematically than ever before. Both fact collection and theory became highly directed activities. The effectiveness and efficiency of electrical research increased accordingly, providing evidence of Francis Bacon’s dictum that “Truth emerges more readily from error than from confusion.”

ANOMALY AND THE EMERGENCE OF SCIENTIFIC DISCOVERIES

Normal science, the puzzle-solving activity is a cumulative enterprise, successful in its aim, the extension of the scope and precision of scientific knowledge. It fits precisely the image of scientific work. Yet one standard product of the scientific enterprise is missing. Normal science does not aim at novelties of fact or theory and, when successful, finds none.

New and unsuspected phenomena are repeatedly uncovered by scientific research, and radical new theories have been invented by scientists. History even suggests that the scientific enterprise has developed a uniquely powerful technique for producing surprises of this sort. If this characteristic of science is to be reconciled with what has already been said, then it seems that research under a paradigm must be a particularly effective way of inducing paradigm change.

That is what fundamental novelties of fact and theory do. Produced inadvertently by a game played under one set of rules, their assimilation requires the elaboration of another set. Examining first discoveries, (or novelties of fact), and then inventions, (or novelties of theory), it becomes clear that the distinction between discovery and invention or between fact and theory proves to be artificial.

THE DISCOVERY OF OXYGEN IN THE 18 CENTURY

Factual and theoretical novelty are closely intertwined in scientific discovery, as shown by a famous example, the discovery of oxygen in the 18 century. Three different men have a legitimate claim to it, and several other chemists must, in the early 1770’s, have had enriched air in a laboratory vessel without knowing it.

(1) The earliest claimant to prepare a relatively pure sample of the gas was the Swedish apothecary, Scheele. His work was not published until after his death, when oxygen’s discovery had repeatedly been announced elsewhere and thus had no effect upon the historical pattern.

(2) The second claimant was the British scientist, Joseph Priestley, who collected the gas released by heated red oxide of mercury. In 1774 he identified the gas thus produced as “nitrous oxide” and in 1775, as “common air with less than its usual quantity of phlogiston”. (“Phlogiston” was a material erroneously supposed to be given off when a substance burns.)

(3) The third claimant, Lavoisier, started the work that led him to oxygen after Priestley’s experiments of 1774 and possibly as the result of a hint from Priestley. Early in 1775 Lavoisier reported that the gas obtained by heating the red oxide of mercury was “air itself entire without alteration except that it comes out more pure, more respirable” By 1777, Lavoisier had concluded that the gas was of a distinct kind, one of the two main constituents of the atmosphere, a conclusion that Priestley was never able to accept.

Who First Discovered Oxygen?

This pattern of discovery raises a question that can be asked about every novel phenomenon. Was it Priestley or Lavoisier, if either, who first discovered oxygen? In any case, when was oxygen discovered? An attempt to produce an answer illuminates the nature of discovery, because there is no answer of the kind that is sought. Discovery is not the sort of process about which this kind of question can be asked. The fact that it is asked, (the priority for oxygen has repeatedly been contested since the 1780’s) is a symptom of something askew in the image of science that gives discovery so fundamental a role.

Priestley

Priestley’s claim to the discovery of oxygen is based upon his priority in isolating a gas that was later recognized as of a distinct kind. But Priestley’s sample was not pure, and, if making

Joseph Priestley and his Working Laboratory

impure oxygen is to discover it, then it has been done by anyone who bottled atmospheric air. Neither did he know he had oxygen.

If Priestley was the discoverer, when was the discovery made? In 1774 he thought he had obtained nitrous oxide, a species he already knew; in 1775 he saw the gas as dephlogisticated air, which is still not oxygen. As, Priestley never recognized what he had prepared as “oxygen” his claim must fail.

Lavoisier

Lavoisier’s claim is stronger, but it has similar problems. The gas he made in 1775 led him to identify it as the “air itself entire,”, but not oxygen. The work in 1776 and 1777 led him to see not merely the gas but what the gas was. In 1777 and to the end of his life Lavoisier insisted that oxygen was an atomic “principle of acidity” and that oxygen gas was formed only when that “principle” united with caloric, the matter of heat. If he did not recognize the gas as an element in its own right, how can he be credited with its discovery?

Antoine Lavoisier in his Laboratory

Is the Issue Impossible to Resolve?

We might say that the issue of who discovered oxygen, and exactly when, is not the kind of question that can be answered by a name and a date. It is too simplistic a question. All that can be said is that the concept of “oxygen” emerged from research done 1770-1780 by a number of workers.

We need a new vocabulary for events like the discovery of oxygen. Though undoubtedly correct, the sentence, “Oxygen was discovered,” misleads by suggesting that discovering something is a single simple act comparable to our concept of seeing. Any attempt to date the discovery must inevitably be arbitrary because discovering a new sort of phenomenon is necessarily a complex event, one which involves recognizing both, (1) that something exists, and (2) exactly what that something is.

THE DISCOVERY OF X-RAYS IN THE LATE 19 C

The emergence of X-rays is a classic case of discovery through accident, which occurs more frequently than impersonal scientific reporting allows us to realize.

Roentgen with His Cathode Ray Apparatus

The Anomaly of a Glowing Screen

The physicist Roentgen interrupted a normal investigation of cathode rays because he had noticed that a barium platinocyanide screen at some distance from his shielded apparatus glowed when the discharge was in process. Investigations showed that the cause of the glow came in straight lines from the cathode ray tube, it cast shadows, could not be deflected by a magnet, and much else besides.

Roentgen convinced himself that his effect was not due to cathode rays but to an agent with some similarity to light. He had performed experiments that did not produce the results anticipated under the current paradigm;

Roentgen’s discovery began with recognising that his screen glowed when it should not. The perception of anomaly, of an effect for which his paradigm had not prepared the investigator, played a role in the perception of novelty. But, the perception that something had gone wrong was only the prelude to discovery. The concept of X-rays had not emerged without a further process of experimentation and assimilation.

One of the First Medical X-Rays – A View of Prof. Von Kölliker’s Hand

When Were X-rays Actually Discovered?

When in Roentgen’s investigation can we say that X-rays had been discovered? Not in the first instant, when there was only a glowing screen. One other investigator had seen that glow and, to his subsequent chagrin, discovered nothing. (William Crookes had found fogged photo-plates near a cathode ray tube.)

Nor, was the moment of discovery during the last week of investigation as Roentgen explored the new radiation he had found. Therefore, we can only say, X-rays emerged as a concept in Würzburg between November 8 and December 28, 1895.

X-rays and Paradigm Shift

Unlike the discovery of oxygen, X-rays were not implicated in any upheaval in scientific theory, for a decade after the event. Can the assimilation of the concept of X-rays have brought about paradigm change? No. The case for denying such a change is very strong. The paradigms held by Roentgen and his peers could not have predicted X-rays. (Maxwell’s electromagnetic theory had not yet been accepted everywhere, and the particulate theory of cathode rays was only one of several current speculations.) But neither did those paradigms prohibit the existence of X-rays.

On the contrary, in 1895 scientific theory and practice knew several forms of radiation, visible, infrared, and ultraviolet. Could X-rays be accepted as one more form of radiation? Why were X-rays not received in the same way as the discovery of an additional chemical element? New elements to fill empty places in the periodic table were still being sought and found in Roentgen’s day. Their pursuit was a standard project for normal science, and success was an occasion only for congratulations, not for surprise.

Resistance to the Concept of X-rays

However, X-rays were greeted not only with surprise but with shock. The distinguished but elderly physicist, William Thompson, Lord Kelvin, at first pronounced them an elaborate hoax. Others, not doubting the evidence, were clearly staggered by it. X-rays were not prohibited by established theory, but they violated deeply entrenched expectations.

By the 1890’s cathode ray equipment was widely used in European laboratories. If Roentgen’s apparatus had produced X-rays, then other experimentalists must have been producing X-rays without knowing it. At the very least, long familiar apparatus would, in future, need to be shielded with lead. Completed work on projects would need to be done again because earlier scientists failed to recognize and control a relevant variable. X-rays opened up a new field and added to the domain of normal science. But they also changed fields that already existed.

THE INVISIBILITY OF REVOLUTIONS

One of the issues that Kuhn was very concerned about was the way in which standard textbooks treated the process of discovery and the history of science. In attempting to produce some clarity for the benefit of beginners they completely falsified the actual history of the subject. The false starts and erroneous paradigms of the past were omitted and scientific development was presented as a smoothly continuous cumulative process leading to the wisdom of their present day.

Kuhn was shocked that scientists, who above all should be concerned with the truth, should be so ready to accept falsehoods that dealt with the true history of their own subject areas. He pinpointed the reluctance of the authors of textbooks to tell the real history of their subject. He characterized their avoiding mention of radical changes as, “The Invisibility of Revolutions”. It was his disquiet at these attitudes which originally impelled him to write his book on scientific revolutions.

Rewriting Textbooks

To an extent unprecedented in other fields, both the layman’s and the practitioner’s knowledge of science is based on textbooks and a few other types of literature derived from them. Textbooks, being teaching instruments for the perpetuation of normal science, have to be rewritten in whole or in part whenever the language, problem-structure, or standards of normal science change. In short, they have to be rewritten in the aftermath of each scientific revolution, and, once rewritten they inevitably disguise not only the role but the very existence of the revolutions that produced them.

Unless he has personally experienced a revolution in his own lifetime, the historical sense either of the working scientist or of the lay reader of textbook literature extends only to the outcome of the most recent revolutions in the field.

Textbooks thus begin by truncating the scientist’s sense of his discipline’s history and then proceed to supply a substitute for what they have eliminated. Characteristically, textbooks of science contain just a bit of history, either in an introductory chapter or, in scattered references to the great heroes of an earlier age. Both students and professionals come to feel like participants in a long-standing historical tradition.

Does Kuhn Overstate his Case?

In textbooks, “partly by selection and partly by distortion, the scientists of earlier ages are implicitly represented as having worked upon the same set of fixed problems and in accordance with the same set of fixed canons that the most recent revolution in scientific theory and method has made seem scientific.”

[I do not think this is true. One can only speak from personal experience, but when I was taught chemistry in the 1950s it was made abundantly clear that the 18 C chemists worked on a different paradigm, notably the “Phlogiston Theory”, and we had to understand the process by which it was eventually overthrown.

Similarly, we were taught about a series of different paradigms for the nature of (1) chemical elements, and (2) atomic structure. From the start we understood that each paradigm was only an approximation to the truth and that the present orthodoxy would probably itself be overturned. Only the word “paradigm” was not in use at the time, but the concept certainly was.

In Physics we were also made aware of paradigm shift by means of the Copernican Revolution, as well as the various changes in our understanding the nature of light. The Caloric Theory of Heat was examined with a view to showing how it was overturned by certain key experiments. Heat as a form of energy became a new orthodoxy, later to be replaced by the Kinetic Theory.

Indeed it was said in the 1960s that students spent too much time on learning about outdated theories and old-fashioned industrial processes. The new approaches were to sweep all this away. – Author]

A Tidy View of Science

Kuhn claims the textbook authors are simply part of a tidying-up process. “No wonder that textbooks and the historical tradition they imply have to be rewritten after each scientific revolution. And no wonder that, as they are rewritten, science once again comes to seem largely cumulative.”

Scientists are not the only group that sees the past of its discipline developing linearly toward its present vantage. The temptation to write history backward is always present. Scientists are more affected by the temptation to rewrite history because, except during crisis and revolution, the scientist’s contemporary position seems so secure.

The depreciation of historical fact is deeply, and probably functionally, ingrained in the ideology of the scientific profession, the same profession that places the highest of all values upon factual details of other sorts.

[This seems to be a very bitter reflection. Could it be that Kuhn, who trained as a physicist but became an academic scientific historian, keenly felt the disdain of his professional scientific colleagues? He had given up the practice of “real” science and thus would never, himself, appear as a name in those textbooks he now so vigorously condemned. Author]

The Faulty Memory of Scientific Pioneers

The sciences, like other professional enterprises, do need their heroes and do preserve their names. Instead of forgetting these heroes, scientists have been able to forget or revise their works. The result is a persistent tendency to make the history of science look linear or cumulative, a tendency that even affects scientists looking back at their own research.

Dalton’s Atomic Theory in the 18 C

All three of the English chemist Dalton’s incompatible accounts of the development of his chemical atomism make it appear that he was interested from an early date in just those chemical problems of combining proportions that he later solved. Actually those problems seem only to have occurred to him with their solutions, and then not until his own creative work was very nearly complete.

What Dalton’s accounts omit are the revolutionary effects of applying to chemistry a set of questions and concepts previously restricted to physics and meteorology. That is what Dalton did, and the result was a reorientation that taught chemists to ask new questions and to draw new conclusions from old data.

Dalton Reflects on His Atomic Theory

Newton, Galileo and Gravity

Newton, (17 C), wrote that Galileo, (16 C) had discovered that the constant force of gravity produces a motion proportional to the square of the time. In fact, Galileo’s kinematic theorem does take that form in the matrix of Newton’s own dynamical concepts. But Galileo said nothing of the sort. His discussion of falling bodies rarely alludes to forces, much less to a uniform gravitational force that causes bodies to fall.

What Newton did was to credit Galileo with the answer to a question that Galileo’s paradigms did not permit to be asked. Newton’s account hides the effect of a small but revolutionary reformulation in the questions asked about motion as well as in the answers that were acceptable.

In the long-term view of physics textbooks, is the constant acceleration produced by a constant force a mere fact that students of dynamics have always sought? Or is it the answer to a question that first arose only within Newtonian theory, and that theory could answer from the body of information available before the question was asked?

Disguising Changes

It is just this sort of change in the questions and answers that accounts, (far more than novel empirical discoveries), for the transition from Aristotelian to Galilean and from Galilean to Newtonian dynamics. The textbook tendency to make the development of science linear, by disguising such changes, hides a process at the heart of scientific development.

The examples above display the reconstruction of history completed by post-revolutionary science texts. More is involved than a multiplication of the misconstructions above. Those misconstructions render revolutions invisible; the material in science texts denies revolutions a function.

Textbooks imply that scientists have always striven for the objectives embodied in today’s paradigms. One by one, like bricks added to a building, scientists have added a fact, concept, law, or theory to the body of information in the contemporary science paradigm.

But that is not the way a science develops. The puzzles of contemporary normal science did not exist until after the most recent scientific revolution. They cannot be traced back to the historic beginning of the science. Earlier generations pursued their own problems with their own instruments and their own canons of solution.

VIEWING SCIENTIFIC CHANGE AS AN EVOLUTIONARY PROCESS

The Supposed Existence of Goals

We are all accustomed to seeing science as an enterprise that draws constantly nearer to some goal set by nature in advance. But need there be any such goal? Can we not account for both science’s existence and its success in terms of evolution from the community’s state of knowledge at any given time?

Do we imagine that there is some, one, full, objective, true account of nature and the measure of scientific achievement is the extent to which we near that ultimate goal? The conceptual transposition proposed is close to one the West undertook in the mid 19 century with the Darwinian Revolution. Interestingly, the main obstacle to this transposition of scientific enquiry is the same as the obstacles to accepting Darwin’s Theory of Natural Selection, namely, the abandonment of the idea of goal-directed change.

The Darwinian Revolution

When Darwin first published his theory of evolution by natural selection in 1859, what most bothered many professionals was neither the notion of species change nor the possible descent of man from apes. The evidence pointing to evolution, including the evolution of man, had been accumulating for decades, and the idea of evolution had been suggested and widely disseminated before. Though evolution did encounter resistance, particularly from some religious groups, it was by no means the greatest of the difficulties the Darwinians faced. That difficulty stemmed from an idea that was Darwin’s own.

Charles Darwin, left in his Late Twenties at the Time of the “Beagle” Expedition, and right in his Seventies During His Researches At His Home at Downe House in Kent

The Abandonment of Goal Directed Change

All the pre-Darwinian evolutionary theories, (Lamarck, Chambers, Spencer,) took evolution to be a goal-directed process. The “idea” of man and of the contemporary flora and fauna was thought to have been present from the first creation
of life, perhaps in the mind of God. That idea or plan had provided the direction and the guiding force to the entire evolutionary process. Each new stage of evolutionary development was a more perfect realization of a plan that had been present from the start.

For many men the abolition of that teleological (goal-directed) kind of evolution was the most significant and least palatable of Darwin’s suggestions. The Origin of Species recognized no goal set either by God or nature. Instead, natural selection, operating in the given environment and with the actual organisms presently at hand, was responsible for the gradual but steady emergence of more elaborate and vastly more specialized organisms.

Darwin Portrayed as an Ape (from a contemporary cartoon in the magazine “Punch”)

Even such marvellously adapted organs as the eye and hand of man, organs whose design had previously provided powerful arguments for the existence of God and an advance plan, were products of a process that moved steadily from primitive beginnings but toward no goal.

The belief that natural selection, resulting from mere competition between organisms for survival, could have produced man, together with the higher animals and plants, was the most difficult and disturbing aspect of Darwin’s theory. What could “evolution” “development” and “progress” mean in the absence of a specified goal? To many people, such terms suddenly seemed self-contradictory.

[This is still the basis of opposition to evolution today, not only among religious fundamentalists, but also various sceptics with a poor understanding of the nature of the theory or the evidence. It is their inability to conceive of non-goal-directed changes bringing about high degrees of complexity.

In addition, it lies behind a reluctance to accept the idea that life itself could have arisen from inorganic materials by a similar natural selection process, so that some have postulated an extra-terrestrial origin for life, if only to put off acceptance of the idea to some distant region, not readily investigable. Author]

The Evolution of Science Without Goals

The analogy relating the evolution of organisms to the evolution of scientific ideas can be pushed too far, but it is very nearly perfect. The process described by Kuhn, “as the resolution of revolutions” is the selection by conflict within the scientific community of the fittest way to practice future science. The net result of these revolutionary selections is the wonderfully adapted set of instruments we call modern scientific knowledge.

Successive stages are marked by an increase in specialization, and the process may have occurred, as biological evolution did, without benefit of a set goal,
or a permanent fixed scientific truth, so each stage in the development of scientific knowledge is simply a better exemplar.

Why should the evolutionary process work? What must nature be like in order that science be possible at all? Why should scientific communities be able to reach a firm consensus unattainable in other fields? Why should consensus endure across one paradigm change after another? And why should paradigm change invariably produce an instrument more perfect in any sense than those known before?

The problem, “What must the world be like in order that man may know it?” was not created by this essay. On the contrary, it is as old as science itself, and it remains unanswered. However, any conception of nature compatible with the growth of science by proof is compatible with the evolutionary view of science developed here.

Authorial Note

[This account is based mainly on Thomas Kuhn’s book, “The Structure of Scientific Revolutions” and though a few parts of it are quoted verbatim I have very heavily edited it by removing the many qualifying clauses which he felt necessary to put in his text. I have added illustrations and made extensive use of subtitles.

The authorial content is usually placed in square brackets, notably the long section on “Does Kuhn Overstate his Case?” where I feel that he is unfair to both textbook writers and to teachers. Furthermore, in “A Tidy View of Science” I suggest a psychological reason for Kuhn’s invective against the writers of textbooks.

The reader is directed to the excellent wikipedia article which also deals in some detail with the response of Kuhn’s contemporaries to his book, the issue of priority, and the debate with his teacher, Michael Polyani. Alan Mason, August 2011]

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