Winning Discussions: post hoc, ergo propter hoc (Effective Pirating)

Winning Discussions: post hoc, ergo propter hoc (Effective Pirating)

Logical fallacies are techniques that people use to make an argument appear convincing even when it is wrong. Learning how to identify and refute logical fallacies is one of the best ways to win in a discussion. Catching an opponent committing a fallacy will force him to retract his error or he will appear foolish or manipulative to his audience. There is a dark side to this. Once you learn to identify logical fallacies you will also be able to use them. Do not deliberately use them against fellow Pirates; it is extreme bad manners and you will most probably be caught out.



The Logical Fallacy – post hoc, ergo propter hoc

This fallacy, often shortened to  the post hoc fallacy, is also known as magical thinking and correlation does not imply causation. It is the claim that because one event occurred before another the first event must have caused the second. We seem to have an evolutionary bias towards this fallacy as the Scientific American points out. An early human, who learned to always associate sudden movement in foliage  with an attack, is far more likely to survive to pass on her genes than one who pauses to logically consider whether it was caused by something harmless or dangerous.

It leads to superstition such as the athlete who always wears the same coloured underwear as when he won his first race. Also it is the basis for many conspiracy theories. We are all victims of our own magical thinking and this should be kept in mind when addressing this fallacy. Be wary of a claim that states because something happend before something else they are neccessarily connected; that a correlation may well exist but it has to be demonstrated.


I was thinking about Suzie just before she rang me.  It must be telepathy. (I do not remember the times I thought of her and she did not ring)

Malaria is caused by bad night air. (The mosquitoes that carry malaria tend to bite at night)

Playing video games leads to violence. (Research is mixed on this issue)

Global warming is caused by the lack of pirates (See featured image)


A scene from the movie The West Wing


You can read more about the ad hoc, ergo propter hoc  logical fallacy in a wikipedia post and logical fallacies in general in this wikipedia article.
Remember that just because someone commits a logical fallacy it does not mean their argument is necessarily incorrect. If you have the time and resources then use the principles of scepticism to test their reasoning objectively.

This article is a part of a series called Effective Pirating:

Winning Discussions: The Fallacy Fallacy (Effective Pirating) 09/01/15
Winning Discussions: The Gambler’s Fallacy (Effective Pirating)
Winning Discussions: argumentum ad ignorantiam (Effective Pirating)
Winning Discussions: post hoc, ergo propter hoc (Effective Pirating)
Winning Discussions: Ad Hominem (Effective Pirating)
Winning Discussions: Appeal to Fear (Effective Pirating) 21/10/14
Winning Discussions: Begging the Question (Effective Pirating) 17/8/14
Winning Discussions – The Bandwagon Fallacy (Effective Pirating) 11/8/14
Effective Pirating: Winning Discussions – Tu Quoque 24/7/14
Effective Pirating: Winning Discussions – The Straw Man 17/7/14
Effective Pirating: Choose your Opponents Carefully 7/7/14

Featured image: CC BY 2.0 John Lester