Post hoc fallacy

The science of logic fascinates me. This is just one of several logical fallacies.

Post hoc ergo propter hoc (Latin: ‘after this, therefore because of this’) is an informal fallacy that states: “Since event Y followed event X, event Y must have been caused by event X.” It is often shortened simply to post hoc fallacy.

The fallacy of Post Hoc Ergo Propter Hoc begins with the observation that two events occurred in sequence. Post hoc is a fallacy because a particular order of events does not necessarily prove a causal relationship between them. It is possible that the temporal ordering is just a coincidence, or is the result of some other factor.


The country’s economy improves right after a new President takes office. We might think that the new President is responsible for the improvement. That might, in fact, be true or partially true, but it is also true that a wide variety of factors influence our national economy.

Cell phone use has been on the rise. Brain tumors have also been on the rise. Therefore, the media reports that cell phone use must be causing an increase in brain tumors, without considering other possible causes, or citing studies.

The belief among various parents that violent video games induce and encourage a violent and rash behavior pattern in the children who play them is a fallacious notion. The behavior of a child depends on multiple factors such as upbringing, parental behavior, environment, type of friends, etc. Hence, one cannot assume that a child will be violent if he/she plays violent video games.

In 2017 I wrote a blog post about an upcoming solar eclipse that got more than two million views (definitely not a usual occurrence). If I concluded that my brilliant writing was the cause for this remarkable increase in views, that would be a post hoc fallacy. There are other reasons why this happened; the primary reason being that there was huge interest in the upcoming eclipse.

What examples have you encountered in your daily life?


This entry was posted in Logic, Uncategorized. Bookmark the permalink.

3 Responses to Post hoc fallacy

  1. weather257 says:

    Yeah…climate change is a major one. Critical thinking is being bred out of humanity!

    Liked by 2 people

  2. Menagerie says:

    I took a logic class in college. It wound up being a lot more than I expected, but it was a great class. First we learned the basics, the logical fallacies. But then, the class went on to present things in equation form. This link has things similar to the stuff we did.

    I wish people were taught this in schools today. I wonder if you could even find this in colleges now?

    Liked by 1 person

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