Texas sharpshooter, also known as the clustering fallacy, is a logical fallacy that is based on our tendency to look for similarities (or patterns) while ignoring differences and randomness.
In this article, we’ll explain when and why this fallacy occurs, as well as show relevant examples of it.
What Is the Texas Sharpshooter?
Texas sharpshooter occurs when someone ignores the differences in the data and overemphasizes the similarities, thus arriving at an inaccurate conclusion.
This type of error typically happens when a person finds and applies an existing pattern that nicely fits into their presumptions.
For example, when someone happens to see a specific license plate number on their way to work, they might think that the odds of seeing that number must be extremely low. However, the odds were in fact the same as for seeing any other license plate number since there was no predetermined significance for seeing that specific number, prior to the fact that the person came across it.
Origin of the Term
The term “Texas sharpshooter” refers to a story in which a gunman, who lacks shooting skills, fires his gun at the side of a barn a number of times. He then paints a bullseye around the tightest cluster of bullet holes, making it appear as if he hit his target, and declares himself a sharpshooter.
For an outsider, the end result may easily seem as if it wasn’t a random act, even though the shooter knows that he or she didn’t really aim at the bullseye.
Why It’s Fallacious
This line of reasoning is fallacious because it fails to take into account all the inconsistencies and randomness in the collected data.
In almost every data collection, there will be coincidental clusters of data; if we randomly generate one hundred coordinates on a specific area — or fire one hundred bullets at the side of a barn — we’ll likely find clusters and patterns that seem like they must have a cause. As humans, we tend to look for patterns (see also clustering illusion) and causes and, consequently, often are quick to assume that a particular pattern must have some sort of significance.
As such, in order for us to get meaningful results from a study, the target has to be pre-specified before we gather the data.
Examples
Here are two real-life examples to better illustrate the fallacy:
Nostradamus
Nostradamus, a French physician and an astrologer, wrote the following texts in his Les Propheties (1555):
- “From the depths of the West of Europe, A young child will be born of poor people, He who by his tongue will seduce a great troop; His fame will increase towards the realm of the East.”
- “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.”
These quatrains are sometimes suggested to be a prediction of Adolf Hitler’s rise to power in Germany and the war against Germany, events that occurred about 400 years later. When read carefully, there really do appear to be some striking similarities in the texts with what happened later.
However, when we dig a little deeper into the mystery, we can find good reasons to believe that the similarities may, in fact, be mere coincidences:
For instance, in his Les Propheties, Nostradamus wrote 942 short poems that are believed to be predictions about the future. The great majority of them turned out to have no significance as predictions and, considering the volume, it’s actually quite likely that we can find at least a few that (seemingly ) apply to later, real events.
Also, in Nostradamus’ writings, the name “Hister” does not refer to an actual person, but to a river called the Danube that is located in central and eastern Europe.
Cancer Clusters
One typical example of the Texas sharpshooter fallacy is the existence of cancer clusters.
There are some areas where the number of cancer cases is unusually high, which in the past has lead people to assume that there must be a causal link, such as contamination of the water supply or air pollution. And, although the reason has really been an environmental cause in a few cases, most of the time there aren’t any apparent causes besides pure randomness.
While there are indeed some examples of cancer cluster studies that have identified a common cause and have advanced scientific knowledge, the vast majority have not. A recent national review of cancer cluster investigations conducted over the past 20 years showed that extensive efforts to find environmental causes of community cancer clusters have not been successful (Goodman et al. 2012).
Environmental Health Technical Brief, Cancer clusters, Connecticut Department of Public Health, 2012.
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