Texas sharpshooter fallacy
Encyclopedia : T : TE : TEX : Texas sharpshooter fallacy
The Texas sharpshooter fallacy is a logical fallacy where information that has no relationship is interpreted or manipulated until it appears to have meaning. The name comes from a story about a Texan who fires several shots at the side of a barn, then paints a target centered on the hits and claims to be a sharpshooter.
The meaning arrived at by the fallacy is typically something the interpreter wishes to be true, but which cannot be confirmed with scientific trials, and would be interpreted differently by someone who was neutral. Such results are statistically non-significant, although guessing about meaning may lead to further speculation that discovers actual causes.
The fallacy is related to the clustering illusion, which refers to the tendency in human cognition to interpret patterns in randomness where none actually exist.
Example
- Attempts to find cryptograms in the works of William Shakespeare, which tended to report results only for those passages of Shakespeare for which the proposed decoding algorithm produced an intelligible result. This is a fallacy, because somebody else selecting different passages would find a different pattern (or more likely, no pattern).
Related logical fallacies
- "The roulette ball has landed on odd numbers eight times in a row. Therefore, there must be something wrong with it." (gambler's fallacy.)
- "More children in town A have leukemia than in town B. Therefore, there must be something wrong with town A." (cum hoc ergo propter hoc or post hoc ergo propter hoc.)
Counterexamples
One should be wary of immediately dismissing the grouping of a set of events which may have a shared underlying physical cause. For example, engineers working with the Space Shuttle were aware of a problem with burnt O-rings that form the inter-segment seals for the solid rocket boosters prior to the Challenger accident. In particular, it was known that the burn-through problem was worse with lower temperatures at launch. Postulating a physical mechanism, one might infer that the O-ring material shrinks or becomes brittle and thereby fails to seal at the moment of launch. With a postulated mechanism, the dataset of several burn-through incidents among twenty-four previous launches becomes highly significant, particularly when ambient temperature is taken as the controlling parameter.
There is also a need for caution when discrediting statistical-based facts. Prior to any postulated mechanism one can infer through statistics on a very reasonable level that phenomena have some characteristics. Also, in certain cases in quantum mechanics, the evidence of a phenomenon cannot be based on anything but statistics, as there are systems which are believed to have "non-accessible inner workings" or even, in a pragmatic approach, "no inner workings". This kind of approach does not give logical certainty, but produces credible results.
See also
External links
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.