Thomas Kuhn: Paradigm Shift
Saul McLeod, PhD
Thomas Kuhn attacks “development-by-accumulation” views of science, which hold that science progresses linearly by accumulating theory-independent facts.
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Simply Psychology
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 of the 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.

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 attempt to remove them consistently fail.

Under these circumstances, the rules for applying the paradigm become relaxed. Ideas that challenge the existing paradigm are developed.

In a 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 that involves a change of paradigm.

Phase 4: Revolution

Eventually, a new paradigm will be established, but not because 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 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 in today’s science when it might be overturned in the 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 that supplant one paradigm with another do not take us closer to the truth about how 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 progressive 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 that paradigm shifts are objective. Truth is relative to the paradigm.

Science does not change its paradigm overnight. 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 in which science takes place. Science is a product of the society in which it is practiced.

References