Saturday, March 3, 2012

What is Texas Sharpshooter Fallacy?

To explain Texas Sharpshooter policy requires telling a story.


There's a sharpshooter in Texas. He has a lot of targets on display, a cluster of shots all around the bullseye. Everybody was awed.

Until someone noticed that on most of these targets, none of the bullseye was in the exact center, the way a real target bullseye should be.

So one night he went to secretly observe the sharpshooter doing target practice.

As it turned out, the sharpshooter was painting the bullseye AFTER he had a cluster of shots.


SIDENOTE: accuracy, vs. precision

Most people use the two words interchangeably, when they are actually quite different.

If you can put 5 shots inside the red circle on a shooting target in a VERY tight cluster, you are both accurate, AND precise.

If you can put 5 shots 3 inches below the red circle in a tight cluster (even though you're aiming for the red circle), you are NOT accurate, but you are precise (little if any scatter)

If you can put 5 shots inside the red circle, but they're spread all over the circle (not a tight cluster), you are accurate, but NOT precise (there's scatter).


The Texas Sharpshooter fallacy is a cognitive trap where the brain chose to shift the remembered position to fit the evidence better.

For example, let's say before the election, you are asked to guess what percentage of votes will a certain candidate get.

A week after the election, you are asked about your guess. Invariably, you will give an answer that's CLOSER to the real number than your actual answer. Your memory shifted to more correspond to the "right" answer.


Scammers often rely on this to shift your position even if you don't remember doing so (and if you do remember, you'd think it was your own idea and it made perfect sense).

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