Post hoc ergo propter hoc

Post hoc ergo propter hoc ( lat. After, therefore ) denotes a fallacy in which the ( correlated ) occurrence of two events is interpreted as a cause or justification without more detailed examination. Since a correlation is not necessarily a causal connection , there is a risk of a spurious correlation . This figure is also known for short as post hoc . When considering several similar cases, credibility is oftenreinforcedby a confirmation error.

Delimitation and description

A related fallacy that can be understood as a more general variant is cum hoc ergo propter hoc . In contrast to cum , Post emphasizes that the supposed effect occurs later than its cause. Unlike with “ cum hoc” , with “ post hoc” it is impossible for both events to swap roles in the interpretation of cause and effect because they occur one after the other. The temporal sequence is necessary for the conclusion on the cause, but not sufficient (see necessary and sufficient condition ). Whether you consider the two inferences side by side as special cases or post hoc as a special case of cum hoc depends on whether you interpret cum as temporal or untimely. In any case, it is an error of the type, non causa pro causa , if there is no causal relationship.

Scheme

The formal form of the post hoc ergo propter hoc is as follows:

	${\ displaystyle A}$ it happened
	${\ displaystyle B}$ happened after ${\ displaystyle A}$
post hoc	${\ displaystyle A}$ has caused ${\ displaystyle B}$

Often there is also generalization about types of events . If it is an undesirable event, post hoc leads to the (equally wrong) reverse conclusion : Avoiding will prevent. The logical rule ex falso quodlibet is violated. ${\ displaystyle B}$ ${\ displaystyle A}$ ${\ displaystyle B}$

Examples

“After I got up with my left foot, the coffee cup fell down. So the "wrong" way of getting up is the reason why my coffee cup falls down. "

The figure works on the principle, step 1: one event occurs before another and step 2: the first is the reason for the second. This thought as logically compelling conclusion to be construed, is incorrect because the temporally earlier event be the cause of the later event indeed could , but the timing but not sufficient to provide a causal link to justify. In the example, the cause of the drop could also be that the person is scared about something.

A tenant moves into a building, and shortly afterwards the condensing system shows a malfunction. The property management holds the tenant responsible. In fact, the tenant did not make any changes to the facility, the events only followed one another in time.

Individual evidence

^ Edward T. Damer: Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments . Wadsworth Publishing, Belmont, CA 1995, ISBN 978-0-534-21750-1 . , Page 131f.

Web links

Holm Bräuer: Post hoc ergo propter hoc . In: Wulff D. Rehfus (Hrsg.): Manual dictionary philosophy (= Uni-Taschenbücher . No. 8208 ). 1st edition. Vandenhoeck & Ruprecht / UTB, Göttingen / Stuttgart 2003, ISBN 3-8252-8208-2 ( philosophie-woerterbuch.de ( memento of April 25, 2013 in the Internet Archive ) - formerly online document No. 701).
Hans Hansen: Fallacies. In: Edward N. Zalta (Ed.): Stanford Encyclopedia of Philosophy .

[1] Edward T. Damer: Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments . Wadsworth Publishing, Belmont, CA 1995, ISBN 978-0-534-21750-1 . , Page 131f.