Demarcation Problem

The demarcation problem is the task of distinguishing genuine science from pseudoscience and non-science.

Definition

The demarcation problem is the question of whether, and by what criterion, scientific theories and practices can be distinguished from non-scientific and pseudoscientific ones.

Scope

This topic covers proposed criteria of demarcation (verifiability, falsifiability, testability), Laudan's argument that the search for a single criterion has failed, and contemporary multi-criterion and family-resemblance approaches that treat pseudoscience as a cluster concept.

Core questions

• Is there a single necessary-and-sufficient criterion for science?
• Does falsifiability succeed where verifiability failed?
• Has the demarcation problem been dissolved or merely complicated?
• Can multiple criteria together mark off pseudoscience?

Key concepts

• verifiability
• falsifiability
• testability
• pseudoscience
• family resemblance

Key theories

Falsifiability criterion

Popper proposes that a theory is scientific only if it is falsifiable, distinguishing empirical science from metaphysics and pseudoscience.

Demise of the demarcation problem

Laudan argues that no proposed criterion succeeds and that 'science' and 'pseudoscience' lack a common essence, so the traditional problem should be abandoned.

Multi-criterion approaches

Hansson and others treat demarcation as requiring several criteria together, identifying pseudoscience by clusters of features rather than a single mark.

History

The Vienna Circle proposed verifiability as a criterion; Popper replaced it with falsifiability in the mid-twentieth century. Laudan's 1983 'Demise of the Demarcation Problem' argued the project had failed, but renewed concern with pseudoscience and policy has driven multi-criterion accounts from the 2000s onward.

Debates

Is demarcation possible at all?

Laudan declares the problem a pseudo-problem with no viable criterion, while Hansson and others argue that demarcation remains tractable using several jointly applied criteria.

Key figures

• Karl Popper
• Larry Laudan
• Sven Ove Hansson

Seminal works

• popper1963
• laudan1983

Frequently asked questions

Why did Popper reject verifiability as the criterion?

Popper observed that pseudosciences like astrology can find confirming instances for almost anything, so verification is too easy. He argued that what marks genuine science is the willingness to specify what would refute a theory, i.e. its falsifiability.