Texas sharpshooter fallacy
The Texas sharpshooter fallacy is an informal fallacy that erroneously stresses patterns in data while ignoring differences. The analogy is that a Texan is firing a number of shots at the side of a barn. He paints a target at the centre of the largest cluster of bullet holes and claims he is a good shot.
The fallacy occurs when forming a hypothesis based on data and then claiming the original data supports the hypothesis. This is not statistically valid because true patterns and coincidences cannot be distinguished. The proper procedure is to verify the hypothesis on new data. In other words, the hypothesis must be stated before comparing it to the data.
The fallacy also occurs when claiming a random occurrence is significant without any justification. If in a game of poker you are fairly dealt a random set of cards, that set of cards is just as likely as any other.
The likely cause of the fallacy is a cognitive bias in humans called apophenia, which is the tendency to perceive false patterns in random data. It is often fueled by confirmation bias as one cherry picking data that fits the perceived pattern.
- Claiming life on Earth is proof of design, when there are many planets that are without life.
- Some people subscribe belief in the SNL curse, painting a figurative bulls-eye around the handful of cast members that have died within its 40 year history while conveniently ignoring the many members that still live; not to mention the innumerable people that have died without ever being a cast member.
- This fallacy is often employed in an attempt to validate the predictions of psychics and prophets. Nostradamus wrote:
- "Beasts wild with hunger will cross the rivers,
The greater part of the battle will be against Hister.
He will cause great men to be dragged in a cage of iron,
When the son of Germany obeys no law."
This verse has been plucked from thousands of obscure quatrains and interpreted to be a prophesy of Hitler's rise to power in Germany, which occurred centuries after the writing. Such an analysis depends upon confirming one's bias by placing undue importance on mention of Germany in the company of an imperfect rhyme of Hitler, and upon ignorance (deliberate or not) that Hister is actually the Latin word for the Danube River.