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Thomas Kuhn - Science as a Paradigm

Thomas Kuhn - Science as a Paradigm

By Saul McLeod, published 2020


Take-home Messages of Kuhn's Idea
  • Thomas Kuhn argued that science does not evolve gradually towards truth.
  • Science has a paradigm which remains constant before going through a paradigm shift when current theories can’t explain some phenomenon, and someone proposes a new theory.
  • A scientific revolution occurs when: (i) the new paradigm better explains the observations, and offers a model that is closer to the objective, external reality; and (ii) the new paradigm is incommensurate with the old.
  • For example, Lamarckian evolution was replaced with Darwin’s theory of evolution by natural selection.

Thomas Kuhn attacks “development-by-accumulation” views of science which hold that science progresses linearly by accumulation of theory-independent facts.  Kuhn looked at the history of science and argued that science does not simply progress by stages based upon neutral observations (e.g. Positivism). 

For Kuhn, the history of science is characterized by revolutions in scientific outlook. Scientists have a worldview or "paradigm".  A paradigm is a universally recognizable scientific achievement that, for a time, provides model problems and solutions to a community of practitioners.

Scientists accept the dominant paradigm until anomalies are thrown up.  Scientists then begin to question the basis of the paradigm itself, new theories emerge which challenge the dominant paradigm and eventually one of these new theories becomes accepted as the new paradigm.

During different periods of science, certain perspectives held sway over the thinking of researchers.  A particular work may “define the legitimate problems and methods of a research field for succeeding generations of practitioners.”


Kuhn's Phases of Science

Knowledge which does not evolve according to the four main phases, according to Kuhn, may not be considered scientific.

paradigm shift cycle

Phase 1: Pre-science

  • The pre-paradigmatic state refers to a period before a scientific consensus has been reached.
  • Disorganized and diverse activity.
  • Constant debate over fundamentals.
  • As many theories as there are theorists.
  • No commonly accepted observational basis. The conflicting theories are constituted with their own set of theory-dependent observations.

Phase 2: Normal Science

(most common – science is usually stable)

  • A paradigm is established which lays the foundations for legitimate work within the discipline. Scientific work then consists in articulation of the paradigm, in solving puzzles that it throws up.
  • A paradigm is a conventional basis for research; it sets a precedent.
  • Puzzles that resist solutions are seen as anomalies.
  • Anomalies are tolerated and do not cause the rejection of the theory, as scientists are confident these anomalies can be explained over time.
  • Scientists spend much of their time in the Model Drift step, battling anomalies that have appeared. They may or may not know this or acknowledge it.
  • It is necessary for normal science to be uncritical. If all scientists were critical of a theory and spent time trying to falsify it, no detailed work would ever get done.

"Normal Science, the activity in which most scientists inevitably spend almost all of their time, is predicated on the assumption that the scientific community knows what the world is like. Much of the success of the enterprise derives from the community's willingness to defend that assumption, if necessary at considerable cost. Normal Science, for example, often suppresses fundamental novelties because they are necessarily subversive of its basic commitments" (Kuhn, 1996, p. 5).

Phase 3: Crisis

  • This is where the paradigm shift occurs.
  • Anomalies become serious, and a crisis develops if the anomalies undermine the basic assumptions of the paradigm and attempts to remove them consistently fail.
  • Under these circumstances the rules for the application of the paradigm become relaxed. Ideas that challenge the existing paradigm are developed.
  • In crisis there will be ‘extraordinary science’ where there will be several competing theories.
  • If the anomalies can be resolved, the crisis is over and normal science resumes. If not, there is a scientific revolution which involves a change of paradigm.

Phase 4: Revolution

  • Eventually a new paradigm will be established, but not as a result of any logically compelling justification.
  • The reasons for the choice of a paradigm are largely psychological and sociological.
  • The new paradigm better explains the observations, and offers a model that is closer to the objective, external reality
  • Different paradigms are held to be incommensurable — the new paradigm cannot be proven or disproven by the rules of the old paradigm, and vice versa.
  • There is no natural measure or scale for ranking different paradigms.

Critical Evaluation

The enormous impact of Thomas Kuhn's work can be measured in the changes it brought about in the vocabulary of the philosophy of science: besides "paradigm shift", Kuhn raised the word "paradigm" itself from a term used in certain forms of linguistics to its current broader meaning.

The frequent use of the phrase "paradigm shift" has made scientists more aware of and in many cases more receptive to paradigm changes, so that Kuhn’s analysis of the evolution of scientific views has by itself influenced that evolution.

For Kuhn, the choice of paradigm was sustained by, but not ultimately determined by, logical processes.  Kuhn believed that it represented the consensus of the community of scientists. Acceptance or rejection of some paradigm is, he argued, a social process as much as a logical process.

This means Kuhn has been accused of being a relativist. Maybe all the theories are equally valid? Why should we believe today’s science when it might be overturned in future? Kuhn vigorously rejected this, claiming that scientific revolutions have always led to new, more accurate theories, and represent true progress.

Does science make progress through scientific revolutions?  Are later paradigms better than earlier ones? No, Kuhn suggests, they are just different.  The scientific revolutions which supplant one paradigm with another do not take us closer to the truth about the way the world is. 

Successive paradigms are incommensurable. Kuhn says that a later paradigm may be a better instrument for solving puzzles than an earlier one.  But if each paradigm defines its own puzzles, what is a puzzle for one paradigm may be no puzzle at all for another.  So why is it progress to replace one paradigm with another which solves puzzles that the earlier paradigm does not even recognize? Kuhn used his incommensurability thesis to disprove the view the paradigm shifts are objective. Truth is relative to the paradigm.

Science does not change its paradigm over night. Younger scientists take a new paradigm forward. As Kuhn put it "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."

Thomas Kuhn showed contemporary philosophers could not ignore the history of science and the social context which science takes place.  Science is a product of the society in which it is practiced.

Discussion Question: Is psychology a pre-science?

Was there a cognitive revolution from behaviorism that changed methodology and assumptions? Is cognitive psychology a new paradigm?  Hints: It's still reductionist, input – output, still uses the experimental method.

APA Style References

Thomas, K. (1962). The structure of scientific revolutions Chicago: University of Chicago Press.

How to reference this article:

McLeod, S. A. (2020, May 01). Thomas kuhn - science as a paradigm. Simply Psychology. https://www.simplypsychology.org/Kuhn-Paradigm.html

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