Definition of False Causality

Logical fallacies are errors in reasoning. An argument might contain no factual errors but still contain fallacies. Many different types of fallacies exist including ad hominem arguments — which are attacks against a person (name-calling) — and false use of authority, which involves using a famous name as support even though that person does not know the topic. Another common fallacy involves cause-effect relationships, termed "false causality."

The fallacy of false causality is also called "false cause" or called by the Latin term, "post hoc, ergo propter hoc," translated as "after this, therefore because of this." A fallacy of false cause indicates that since one event followed another in time, the first must have caused the second. While a causal relationship might actually exist, the statement does not give enough information to illustrate truth behind the connection. Such statements jump to a conclusion implying a causal relationship without supporting evidence.

Statements using false causation might seem clearly ridiculous, such as the example given by Fallacy Files: "Roosters crow just before the sun rises. Therefore, roosters crowing cause the sun to rise." Others are less obvious. For instance, if your computer crashes immediately after you installed new software, assuming the software caused the crash represents a post hoc fallacy without further investigation to find out if the software is truly the single cause of the problem.

The fallacy of false cause often appears in arguments when factions use statistics to bolster a claim. For example, a speaker or writer may insist that seat belt laws save lives and might cite reduced numbers of traffic fatalities after seat belt laws went into effect as proof. However, other reasons may account for the reduction in deaths such as other legislation and more cars equipped with airbags. The statistics themselves may also mislead listeners or readers if numbers of drivers change, but the causal relationship is based upon numbers of deaths rather than a percentage of traffic.

The effects of causal fallacies spill into aspects of culture in the form of superstitions. A sick person who gets better after treatment by a magician, faith healer or alternative medicine may ascribe the recovery to the treatment when the connection might be coincidental. Folk remedies often spring from such situations. The fallacy occurs when science cannot prove the causal connection, and instead, people use only the succession in time as evidence of cause and effect.