Falsifiability tests

Lens adapted to this topic: The standard account and its methodological uses

This perspective treats falsifiability as a valuable testing principle: a good hypothesis should exclude at least some possible observations, making it vulnerable to empirical disconfirmation. It is especially useful for formulating risky predictions and ruling out explanations, while statistical and scientific practice also relies on controls, replication, causal identification, and accumulated evidence rather than on isolated falsifications alone.

• A theory is falsifiable when, under specified conditions, it rules out some possible empirical observations that could contradict it.
• Falsification is logically asymmetric with universal confirmation: one counterexample can conflict with a universal claim, while repeated confirming observations do not establish it with certainty.
• Scientific testing commonly combines falsification with reproducibility, controls, and methods for distinguishing causal relationships between variables and observables.
• In applied causal research, falsification tests examine observable implications of assumptions needed for an identification strategy, including instrumental-variables methods.
• Some researchers propose making falsifiability more quantitative by relating it to Bayesian model selection and model complexity.

Lens adapted to this topic: Critiques of falsifiability-only testing

This perspective argues that falsifiability is too weak or too narrow to define science by itself. A claim can be made falsifiable through ad hoc or poorly discriminating tests, while important scientific theories may be difficult to test directly or gain support through prediction, explanation, and converging evidence. Critics therefore treat falsifiability as a diagnostic tool rather than a complete demarcation rule.

• Falsifiability alone may fail to distinguish science from pseudoscience because superficially testable claims can still be protected by weak or improvised testing arrangements.
• Some scientifically important work is not easily captured by a simple falsifiability criterion, including aspects of evolutionary biology and string theory discussed by critics of the criterion.
• Descriptions of actual scientific practice emphasize repeated and varied observations, confirmation, controls, and reproducibility, not only attempts to falsify theories.
• A failed falsification test may reflect problems in auxiliary assumptions, measurement, or research design rather than showing that the focal theory itself is false.
• Critics of Popperian falsificationism argue that its strict anti-inductivist account is not widely endorsed by contemporary philosophers of science.