# Paradigm shift

> A scientific community can replace the shared examples, standards, and concepts that organise its normal work.

- HTML version: https://robbiepalmer.me/ideas/paradigm-shift
- Source: https://plato.stanford.edu/entries/thomas-kuhn/#DeveScie

A paradigm shift changes the framework within which a community identifies
problems, conducts inquiry, and judges solutions. Thomas Kuhn developed this
account from the history of science. Scientific development, on his view, is
not always the steady addition of facts to one stable picture.

Kuhn used "paradigm" in several related senses. His later term "disciplinary
matrix" names the shared commitments of a scientific community: symbolic
generalisations, models, values, and exemplary solutions. Textbook problems and
accepted achievements teach practitioners how to see new work as a problem of
a familiar kind.

## Normal science and anomaly

Most research is normal science. Practitioners accept a disciplinary matrix and
solve puzzles within it. This commitment is productive. It lets a community
develop instruments, refine measurements, and pursue questions that would be
impossible if every basic commitment reopened each morning.

An anomaly is a persistent failure of expectation. One anomalous result does
not force a revolution. Researchers first check the experiment, revise an
auxiliary assumption, or try to extend the existing account. This conservatism
is not simply stubbornness. A framework must be stable long enough to reveal
where its hardest problems lie.

A crisis can arise when important anomalies resist those efforts and confidence
in the existing framework weakens. If a rival framework reorganises the field
and attracts a community, a scientific revolution has occurred. The new
framework may change the accepted problems and standards as well as their
answers.

The transition from Newtonian mechanics to relativity is not just a correction
to a value in an otherwise fixed theory. Concepts such as mass, space, and time
take different roles in the two accounts. The later theory recovers useful
Newtonian results within limited conditions, but it does not leave the older
conceptual structure untouched.

## A shift is more than a surprising discovery

"Paradigm shift" is often used for any major change. Kuhn's claim is narrower.
A discovery can be dramatic while normal science absorbs it. A paradigm shift
revises the framework used to define and evaluate the work.

This difference prevents the idea from turning into a synonym for novelty. A
new observation, instrument, or theory matters here only if it contributes to a
change in the community's disciplinary matrix. The relevant evidence includes
new textbooks, model problems, classifications, and standards of success, not
just a celebrated result.

## What survives a revolution

A shift need not make every earlier observation worthless. It changes what
records mean and which comparisons remain licensed. Some measurements can be
translated, some remain useful within a restricted range, and some must be
regenerated because their categories or procedures assumed the older framework.

This sharper sense preserves an important argument: a change in worldview can
invalidate an old use of data without erasing the marks that were recorded.
Labels may divide the world differently. Measures may no longer track the same
quantity. Evaluation rules may reward a different result. The cost of a shift
therefore includes finding which evidence transfers and which does not.

[Theory-ladenness](/ideas/theory-ladenness) explains why evidence carries those
dependencies. [Incommensurability](/ideas/incommensurability) explains why
comparison across the change can become partial and difficult. The broader
[postpositivist](/ideas/postpositivism) lesson is that standards and observation
have histories, even when inquiry still aims to detect error and improve its
account of the world.

## Sources

* Bird, Alexander. ["Thomas
  Kuhn"](https://plato.stanford.edu/archives/fall2022/entries/thomas-kuhn/#DeveScie). *The
  Stanford Encyclopedia of Philosophy*, 2022.
* Kuhn, Thomas S. *The Structure of Scientific Revolutions*. Fourth edition.
  University of Chicago Press, 2012.
* Kuhn, Thomas S. *The Essential Tension*. University of Chicago Press, 1977.

## Related ideas

- [Adaptive Planning](https://robbiepalmer.me/ideas/adaptive-planning.md): Hold the goal steady, treat the plan as a hypothesis, and revise the route as work produces evidence.
- [Incommensurability](https://robbiepalmer.me/ideas/incommensurability.md): Rival frameworks may lack a complete common measure because their concepts, problems, or standards differ.
- [Postpositivism](https://robbiepalmer.me/ideas/postpositivism.md): Empirical inquiry can pursue objectivity while accepting fallible evidence, theory-laden observation, and the influence of values.
- [Theory-ladenness](https://robbiepalmer.me/ideas/theory-ladenness.md): Observations depend on prior ideas about what to notice, how to measure it, and what the result means.

## Where it appears

- Blog post: [The Philosophy of Data Science](https://robbiepalmer.me/blog/2022-03-02-the-philosophy-of-data-science.md)

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