Philosophy of Science
Science vs Pseudoscience
Demarcation problem — what makes something science vs pretending to be?
The demarcation problem in philosophy of science: how to distinguish science from pseudoscience or non-science. Karl Popper (1934): falsifiability — scientific claims must be falsifiable (testable, could be proven false). Astrology: not falsifiable (predictions vague). Modern: more nuanced — features include testability, peer review, predictive power, mechanism, integration with other knowledge. Examples often called pseudoscience: astrology, homeopathy, intelligent design, conspiracy theories. Demarcation: practical importance for policy, education, public understanding. Continues to be debated; no clean criterion.
- QuestionHow to distinguish science from non-science
- Popper's criterionFalsifiability (testability)
- Modern viewMultiple criteria; spectrum
- Pseudoscience featuresUnfalsifiable, ad hoc rescue, lack of peer review, no mechanism
- Examples disputedAstrology, homeopathy, intelligent design, conspiracy
- Practical importancePolicy, medicine, education, public understanding
Interactive visualization
Press play, or step through manually. The visualization is yours to drive — try it before reading on.
Watch the 60-second explainer
A condensed visual walkthrough — narrated, captioned, under a minute.
Why demarcation matters
- Public policy. Funding decisions.
- Medicine. Approving treatments.
- Education. Curriculum decisions.
- Public understanding. Distinguishing claims.
- Critical thinking. Evaluating evidence.
- Philosophy of science. Major problem.
- Combating misinformation. Increasingly important.
Common misconceptions
- Sharp line. Often spectrum.
- One criterion suffices. Multiple needed.
- Pseudoscience always wrong. Some practitioners sincere; ideas potentially testable.
- Demarcation simple. Active debate.
- Just labeling. Real differences in methods.
- All non-mainstream is pseudoscience. Different categories.
Frequently asked questions
What's the demarcation problem?
How to distinguish science from non-science (especially pseudoscience). Important: deciding which claims to take seriously, allocate resources to, teach, regulate. Initial answer (Popper): falsifiability. More nuanced now: many criteria; demarcation often a spectrum, not sharp line. Active debate in philosophy of science.
What's Popper's falsifiability?
Karl Popper (1934). Scientific claims must be falsifiable: have specific predictions that could fail. Tested: predictions checked. Survive: provisionally accepted. Fail: theory must change. Astrology: predictions vague, can't really fail; not science. Pseudoscience: makes claims that can't be tested; or rescues theory ad hoc when predictions fail. Fundamental Popperian criterion.
What are pseudoscience markers?
Multiple. (1) Vague claims; can't be falsified. (2) Ad hoc rescues: when predictions fail, modify theory to keep core. (3) Lack of peer review or quality control. (4) Use of technical-sounding language without precise meaning. (5) Lack of mechanism or integration with established science. (6) Reliance on testimonials over evidence. (7) Absolute claims; resistance to revision.
What's wrong with astrology?
Multiple issues. (1) Predictions vague: applies to many people; can interpret as confirmed. (2) When specific predictions fail: rescued by other factors. (3) Mechanism: unclear how planets affect human personality. (4) Doesn't integrate with physics, biology. (5) Repeated controlled tests: no significant correlation between zodiac signs and personality. Despite popularity: doesn't meet science criteria.
What about homeopathy?
System of "treatment" using extreme dilutions. Diluted to point where no original substance remains. Mechanism: unclear (water memory not supported). Empirical tests: most show no effect beyond placebo. Yet: large industry. Counts as pseudoscience by most demarcation criteria. Difference from real medicine: lack of mechanism, lack of effect, lack of peer-reviewed support.
What about intelligent design?
Variant of creationism. Argues: certain biological features show design (irreducible complexity). Critics: arguments use ad hoc reasoning; gaps explained by current science; doesn't propose testable predictions; mechanism (designer) unclear. Most: not science. Court rulings (Kitzmiller v. Dover, 2005): not science. Religious belief; not science.
Are all "pseudosciences" equally pseudoscientific?
Spectrum. Some clearly outside science (astrology). Others: borderline (parapsychology — controlled studies with mixed results). Some: previously rejected then accepted (germ theory was rejected). Some: still legitimate fields with questionable claims. Demarcation: not always clean. Important: criticize specific claims, not just label entire fields.