Post hoc ergo propter hoc (Latin: 'after this, therefore because of this') is an informal fallacy that assumes event Y was caused by event X simply because Y followed X in time. This logical fallacy of questionable cause differs from cum hoc ergo propter hoc, where events occur simultaneously. The error arises when correlation is mistaken for causality without considering other factors. A famous example is believing the rooster crowing causes the sun to rise, ignoring that one event does not necessarily cause the other.
Pattern
The form of the post hoc fallacy is expressed as follows:
- A occurred, then B occurred.
- Therefore, A caused B.
When B is undesirable, this pattern is often combined with the formal fallacy of denying the antecedent, assuming the logical inverse holds: believing that avoiding A will prevent B.4
Examples
- A tenant moves into an apartment and the building's furnace develops a fault. The manager blames the tenant's arrival for the malfunction. One event merely followed the other, in the absence of causality.5
- Brazilian footballer Pelé blamed a dip in his playing performance on having given his playing shirt to a fan. His play recovered after a friend, sent to retrieve the shirt from the fan, returned a shirt claimed to be the original (though it was actually just the shirt Pelé had worn during his previous poor performance, as the original could not be tracked down).6
- Reporting of coincidental vaccine adverse events, where people have a health complaint after being vaccinated and assume it was caused by the vaccination.7
See also
- Apophenia – Tendency to perceive connections between unrelated things
- Affirming the consequent – Type of fallacious argument (logical fallacy)
- Association fallacy – Formal fallacy
- Cargo cult – New religious movement
- Causal inference – Branch of statistics concerned with inferring causal relationships between variables
- Coincidence – Concurrence of events with no connection
- Confirmation bias – Bias confirming existing attitudes
- Correlation does not imply causation – Refutation of a logical fallacy
- Jumping to conclusions – Psychological term
- Magical thinking – Belief in the connection of unrelated events
- Superstition – Belief or behavior that is considered irrational or supernatural
- Survivorship bias – Logical error, form of selection bias
- Surrogate endpoint – Biomarker proxy outcome measure
- Temporality – Concept in philosophy
- Texas sharpshooter fallacy
Bibliography
- Woods, J. H., Walton, D. N. (1977). Post Hoc, Ergo Propter Hoc.
- Mommsen, J. K. F. (2013). Wider Das Post Hoc Ergo Propter Hoc - Primary Source Edition. United States: BiblioLife.
- Woods, J., Walton, D. (2019). Fallacies: Selected Papers 1972–1982. Germany: De Gruyter.
References
Grouse, Lawrence (2016). "Post hoc ergo propter hoc". Journal of Thoracic Disease. 8 (7): E511 – E512. doi:10.21037/jtd.2016.04.49. ISSN 2072-1439. PMC 4958779. PMID 27499984. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958779 ↩
"post hoc". LII / Legal Information Institute. Retrieved 2021-08-28. https://www.law.cornell.edu/wex/post_hoc ↩
"Correlation vs Causation". KnowledgeSpace. 2015-10-09. Retrieved 2021-08-28. https://knowledgespace.com.au/correlation-vs-causation/ ↩
Summers, Jesse S. (24 March 2017). "Post hoc ergo propter hoc : some benefits of rationalization". Philosophical Explorations. 20 (sup1): 21–36. doi:10.1080/13869795.2017.1287292. S2CID 151401300. https://doi.org/10.1080%2F13869795.2017.1287292 ↩
Damer, T Edward (1995). Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments (3rd ed.). Belmont, CA: Wadsworth Publishing. p. 131. ISBN 978-0-534-21750-1. OCLC 30319422. 978-0-534-21750-1 ↩
Macaskill, Sandy (2009-02-25). "Top 10: Football superstitions to rival Arsenal's Kolo Toure". The Telegraph. Archived from the original on 2010-08-26. https://www.telegraph.co.uk/sport/football/teams/arsenal/4805924/Top-10-Football-superstitions-to-rival-Arsenals-Kolo-Toure.html ↩
Manktelow, K. I. (2012). Thinking and Reasoning: An Introduction to the Psychology of Reason, Judgment and Decision Making. Psychology Press. p. 119. ISBN 9781841697413. 9781841697413 ↩