A paradigm shift is the term first used by Thomas Kuhn in his famous 1962 book The Structure of Scientific Revolutions to describe the process and result of a change in basic assumptions within the ruling theory of science. It has since become widely applied to many other realms of human experience as well.
Examples of paradigm shifts in science
- The transition from a Ptolemaic cosmology to a Copernican one.
- The unification of classical physics by Newton into a coherent mechanical worldview.
- The transition between the Maxwellian Electromagnetic worldview and the Einsteinian Relativistic worldview.
- The transition between the worldview of Newtonian physics and the Einsteinian Relativistic worldview.
- The development of Quantum mechanics, which overthrew classical mechanics.
- The development of Darwin's theory of evolution by natural selection, which overturned Lamarckian theories of evolution by inheritance of acquired characteristics.
- The acceptance of Plate tectonics as the explanation for large-scale geologic changes.
Kuhnian Paradigm Shifts
In laymen terms
Put in the simplest possible way a paradigm shift can be described as a step away from some collective folly, or a removal of a common misconception (within the scientific community - that's why it's so embarrassing, scientists don't suffer from misconceptions by definition).
Before the step is taken three things are at hand: 1) there is a lack of direct knowledge about a particular thing X, 2) everybody, every scientist that is, thinks that X is Y, and 3) there are irrefutable but ignored indications that X can not be Y.
The step, the paradigm shift, comes when some "young fool" takes the ignored indications at face value, refuses to accept the misconception, and gives a proper explanation of what X must be in face of the already present indirect knowledge of X.
In expert terms
A scientific revolution occurs, according to Kuhn, when scientists encounter anomalies which cannot be explained by the universally accepted paradigm within which scientific progress has thereto been made. The paradigm, in Kuhn's view, is not simply the current theory, but the entire worldview in which it exists, and all of the implications which come with it. There are anomalies for all paradigms, Kuhn maintained, that are brushed away as acceptable levels of error, or simply ignored and not dealt with (a principle argument Kuhn uses to reject Karl Popper's model of falsifiability as the key force involved in scientific change). Rather, according to Kuhn, anomalies have various levels of significance to the practitioners of science at the time. To put it in the context of early 20th century physics, some scientists found the problems with calculating Mercury's perihelion more troubling than the Michelson-Morley experiment results -- and some, the other way around. Kuhn's model of scientific change differs here, and in many places, from that of the logical positivists in that it puts an enhanced emphasis on the individual humans involved as scientists, rather than abstracting science into a purely logical or philosophical venture.
When enough significant anomalies have accrued against a current paradigm, the scientific discipline is thrown into a state of crisis, according to Kuhn. During this crisis, new ideas, perhaps ones previously discarded, are tried. Eventually a new paradigm is formed, which gains its own new followers, and an intellectual "battle" takes place between the followers of the new paradigm and the hold-outs of the old paradigm. Again, looking at early 20th century physics, the transition between the Maxwellian electromagnetic worldview and the Einsteinian Relativistic worldview was not instantaneous nor calm, and instead involved a protracted set of "attacks," both with empirical data as well as rhetorical or philosophical arguments, by both sides, with the Einsteinian theory winning out in the long-run. Again, the weighing of evidence and importance of new data was fit through the human sieve: some scientists found the simplicity of Einstein's equations to be most compelling, while some found them more complicated than the notion of Maxwell's aether which they banished. Some found Eddington's photographs of light bending around the sun to be compelling, some questioned their accuracy and meaning. Sometimes the convincing force is just time itself and the human toll it takes, Kuhn pointed out, using a quote from 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."
After a given discipline has changed from one paradigm to another, this is called, in Kuhn's terminology, a scientific revolution or a paradigm shift. It is often this final conclusion -- the result of the long process -- that is meant when the term paradigm shift is used colloquially: simply the (often radical) change of worldview, without reference to the specificities of Kuhn's historical argument.
A common misinterpretation of Kuhnian paradigms is the belief that the discovery of paradigm shifts and the dynamic nature of science (with its many opportunities for subjective judgments by scientists) is a case for relativism: the view that all kinds of belief systems are equal, such that magic, religious concepts or pseudoscience would be of equal working value to true science. Kuhn vehemently denies this interpretation and states that when a scientific paradigm is replaced by a new one, albeit through a complex social process, the new one is always better, not just different.
These claims of relativism are, however, tied to another claim that Kuhn does at least somewhat endorse: that the language and theories of different paradigms cannot be translated into one another or rationally evaluated against one another — that they are incommensurable. This gave rise to much talk of different peoples and cultures having radically different worldviews or conceptual schemes — so different that whether or not one was better, they could not be understood by one another. However, the philosopher Donald Davidson published a highly-regarded essay in 1974, "On the Very Idea of a Conceptual Scheme," arguing that the notion that any languages or theories could be incommensurable with one another was itself incoherent. If this is correct, Kuhn's claims must be taken in a weaker sense than they often are. Furthermore, the hold of the Kuhnian analysis on social science has long been tenuous with the wide application of multi-paradigmatic approaches in order to understand complex human behaviour (see for example John Hassard, Sociology and Organisation Theory. Positivism, Paradigms and Postmodernity. Cambridge University Press. 1993.)
The term "paradigm shift" has found uses in other contexts, representing the notion of a major change in a certain thought-pattern — a radical change in personal beliefs, complex systems or organizations, replacing the former way of thinking or organizing with a radically different way of thinking or organizing:
- Margaret Mead, noted anthropologist, shows a flashlight to the indigenous New Guinea people.
- People blind since birth are suddenly enabled to see.
- Development of new techniques in genetics impact long-standing assumptions in anthropology.
- An apparently miraculous healing is witnessed by someone who has never believed in miracles.
- Conversion experiences, and the resulting shifts in ideology and social behavior.
Examples of paradigm shifts in complex systems and organizations:
- The English monarchy with the signing of the Magna Carta.
- The "explosion of life" marking the end of the Pre-Cambrian Era.
- Society with the invention of any of several innovations (fire, the wheel, gunpowder, the microchip, etc.).
- Warfare and corporate structure with the development of the Prussian military model.
- Culture bias
- Cognitive bias
- Notation bias
- Confirmation bias
- Infrastructure bias
- Disruptive technology