Post+Hoc+Fallacies

Post Hoc Fallacy Traditionally referred to as the post hoc, ergo propter hoc or "after this, therefore because of this" fallacy, this idea directly addresses the distinction between correlation and causation. People often think that if one event A occurs and another distinct event B occurs there after, by direct logic event A must have caused event B. However, this is not always the case. Thus the Post Hoc Fallacy acknowledges that correlation and causation are different, and simply because event B occurred after event B does not necessarily mean event B was a result of event A. Clearly the obvious distinction between correlation and causation is blurred, and therefore it is important that such differing ideas are distinguished here. In example, the fact that every New Year's Eve millions of people get drunk and die in vehicle related accidents is not a cause- effect event, but rather a strong correlation, for the new year itself does not make people get drunk and essentially get into an accident and die. On the converse, the fact that people are killed because of their level of intoxication is, in effect, a cause effect example, for in this case it is an individual's drunken state directly that causes them to be impaired and thus crash and die. Though apparently similar, the distinction among causation and correlation is significant and must accurately be understood in order to truly understand the Post Hoc Fallacy.

This picture represents one of the most common misconceived cause and effect events. Farmers used to assume that it was because the rooster crowed that the sun began to rise, however, it quickly becomes clear that regardless of if the rooster crows or not, the sun continues to rise, and therefore the this is a correlation as opposed to a direct causation. media type="youtube" key="MTbZoKEOkUg&hl=en&fs=1" height="344" width="425" This clip, taken from one of the many Friends episodes accurately depicts the Post Hoc Fallacy. Joey's friend Rachel has just moved into to his apartment and mere days later, his refrigerator breaks. Joey jumps to the conclusion that the fridge broke once Rachel moved in, thus she must have broken it. However, again this is a simple correlation for there is no way that Rachel's act of moving in could have directly caused the fridge to break.

[|The Nizkor Project: The Post Hoc Fallacy] [|Fallacy Files: Post Hoc] [|The skeptics Guide to the Universe]

Sample Problem Which situation ACTUALLY represents a cause effect relationship? a. the medicine man sings in the spring, a few weeks later it rains b. the rooster crows in the morning, the sun begins to rise c. Drinking impairs an individual's judgment d. a blackout in New York causes a baby boom 9 months later

correct answer: c, all other examples are correlation, not cause and effect.