View source for Post hoc ergo propter hoc

{{short description|Fallacy of assumption of causality based on sequence of events}}
{{About|the informal fallacy|the West Wing episode|Post Hoc, Ergo Propter Hoc (The West Wing)||Post hoc (disambiguation){{!}}Post hoc}}{{Italic title}}
'''''Post hoc ergo propter hoc''''' ([[Latin]]: 'after this, therefore because of this') is an [[informal fallacy]] which one commits when one reasons, "Since event Y ''followed'' event X, event Y must have been ''caused'' by event X." It is a fallacy in which an event is presumed to have been caused by a closely preceding event merely on the grounds of temporal succession. This type of reasoning is fallacious because mere temporal succession does not establish a causal connection. It is often shortened simply to '''''post hoc fallacy'''''. A logical fallacy of the [[questionable cause]] variety, it is subtly different from the fallacy ''[[correlation does not imply causation#General pattern|cum hoc ergo propter hoc]]'' ('with this, therefore because of this'), in which two events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a logical fallacy in which one event seems to be the cause of a later event because it occurred earlier.<ref>{{Cite journal|last=Grouse|first=Lawrence|title=Post hoc ergo propter hoc|journal=Journal of Thoracic Disease|year=2016|volume=8|issue=7|pages=E511–E512|doi=10.21037/jtd.2016.04.49|issn=2072-1439|pmc=4958779|pmid=27499984 |doi-access=free }}</ref>

''Post hoc'' is a particularly tempting error because correlation sometimes appears to suggest [[causality]]. The fallacy lies in a conclusion based ''solely'' on the order of events, rather than taking into account other factors potentially responsible for the result that might rule out the connection.<ref>{{Cite web|title=post hoc|url=https://www.law.cornell.edu/wex/post_hoc|access-date=2021-08-28|website=LII / Legal Information Institute|language=en}}</ref>

''Post hoc ergo propter hoc'' is an easy fallacy to detect when it is blatant, but even the best of scientists and statesmen are occasionally misled by it.

== 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 [[inverse (logic)|logical inverse]] holds: believing that avoiding '''A''' will prevent '''B'''.<ref>{{cite journal |last1=Summers |first1=Jesse S. |title=Post hoc ergo propter hoc : some benefits of rationalization |journal=Philosophical Explorations |date=24 March 2017 |volume=20 |issue=sup1 |pages=21–36 |doi=10.1080/13869795.2017.1287292|s2cid=151401300 |doi-access=free }}</ref>

== Examples ==<!-- Two examples are plenty, and we will only accept material that is sourced from a published work (preferably a textbook) on logic. -->
* 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.<ref>{{cite book |title= Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments|last= Damer|first= T Edward|author-link= T. Edward Damer|edition= 3rd|year= 1995|publisher= Wadsworth Publishing|location= [[Belmont, California|Belmont, CA]]|isbn= 978-0-534-21750-1|oclc= 30319422|page= 131}}</ref>
* Brazilian footballer [[Pelé]] blamed a dip in his playing performance on having given a fan a specific playing shirt. His play recovered after receiving from a friend what he was told was the shirt in question, despite it actually being the same shirt he'd worn during his poor performance.<ref>{{Cite news|url=https://www.telegraph.co.uk/sport/football/teams/arsenal/4805924/Top-10-Football-superstitions-to-rival-Arsenals-Kolo-Toure.html|title=Top 10: Football superstitions to rival Arsenal's Kolo Toure|last=Macaskill|first=Sandy|date=2009-02-25|work=[[The Daily Telegraph|The Telegraph]]|archive-url=https://web.archive.org/web/20100826041515/https://www.telegraph.co.uk/sport/football/teams/arsenal/4805924/Top-10-Football-superstitions-to-rival-Arsenals-Kolo-Toure.html|archive-date=2010-08-26|url-status=live}}</ref>
* Reporting of coincidental [[vaccine adverse event]]s, where people have a health complaint after being vaccinated and assume it was caused by the vaccination.<ref>{{cite book|url=https://books.google.com/books?id=2Lmfug12yFkC&pg=PA119|title=Thinking and Reasoning: An Introduction to the Psychology of Reason, Judgment and Decision Making|last=Manktelow|first=K. I.|year=2012|publisher=Psychology Press|isbn=9781841697413|page=119}}</ref>

==See also==
* {{annotated link|Apophenia}}
* {{annotated link|Affirming the consequent}}
* {{annotated link|Association fallacy}}
* {{annotated link|Cargo cult}}
* {{annotated link|Causal inference}}
* {{annotated link|Coincidence}}
* {{annotated link|Confirmation bias}}
* {{annotated link|Correlation does not imply causation}}
* {{annotated link|Jumping to conclusions}}
* {{annotated link|Magical thinking}}
* {{annotated link|Superstition}}
* {{annotated link|Survivorship bias}}
* {{annotated link|Surrogate endpoint}}
* [[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==
{{reflist}}

{{Fallacies}}
{{Time in philosophy}}

[[Category:Causal fallacies]]
[[Category:Latin logical phrases]]