Fallacy Friday: Sharpshooter Fallacy

On this Fallacy “Good” Friday, we’ll take a look at a logical error that I pointed out in a recent post. It’s formally called ‘non causa pro causa’; I call it the Sharpshooter Fallacy.

The Texas Sharpshooter is a fabled marksman who fires his gun randomly at the side of a barn, then paints a bull’s-eye around the bullet holes – to obviously make it look like he is an amazing shot. The fallacy is applied to the field of logic to describe a false effect after-the-fact. Information that has no relationship is interpreted or manipulated until it appears to have meaning.

Seeing a Face in the Clouds
This fallacy is similar to one of our earlier fallacies, post hoc ergo propter hoc. The fallacy is to assert that because two events occur together, they must be causally related. It's a fallacy because it ignores other factors that may be the cause(s) of the events.

What appears to be statistically significant (not due to chance) is actually expected by the laws of chance. This is probably best shown in the act of reading tea leaves or casting bones, as we’ve read about in old tales. The positioning of the leaves or bones isn’t significant or special; it’s just an artifact of randomness. The fallacy occurs when people try to place unreasoned meaning upon these artifacts.

What a Coinkydink!
When someone jumps to the conclusion that a cluster in some data must be the result of a cause--usually one that it is clustered around--they’ve fallen for the sharpshooter’s trick. When looking at data, there is a danger of jumping to a conclusion that a random cluster is a causal pattern.

What makes this fallacy dangerous is that, to the untrained eye, it can look a lot like what real scientists really do when they look at data and draw conclusions. There are other tests you can run to find the probability of a certain thing, but this is often overlooked by those who *want* there to be meaning where there is none (i.e., the self-made prophecy).

This problem is at the heart of the fine-tuning argument as scientific evidence for a god. There’s no reason to think that the universe is fine-tuned for life – actually, evolution shows that life is fine-tuned for the universe! The ‘fine-tuned’ argument is just like throwing six, six-sided dice. They come up, say ‘3, 6, 3, 2, 1, 1’. The odds of that happening are 1 in 1,679,616 chance!!! The fallacy is (obviously) that you’re counting it up after-the-fact. It’d be like saying “what are the odds that we’d draw the letter A the way we do?” like it’s got some sort of significant meaning. Without further testing, such a conclusion is seldom justified.

-STA

Day In The Life: Coincidences

So I’m at work, and I overhear my boss telling the new hire, “How is it that on the exact same day that [newly fired worker] pisses me off and we let him go, that you’re able to start and get the job done that has a deadline today?”

What Are The Odds?
The subject of his mind-numbing conversation was, of course, God. My coworker’s response was something like, “Well, Einstein said ‘God doesn’t play dice with the universe’, but I don’t know.”

Not wanting to get into that conversation, I changed the subject and asked my boss about a meeting the next day, and made sure the subject had shifted to something more reasonable.

The conclusion to this chatter is of course: there are no coincidences. O RLY?!

This matter-of-fact phrase is ripe with a logical error known as the sharpshooter fallacy (look for it in our next Fallacy Friday). Simply put, how many times did you notice when the coincidence didn’t happen?

Count The Hits, Forget The Misses
How often do we hear that an airplane landed safely at its destination? How much good news do you see in the paper, or on the 6 o’clock broadcast? The reason you do is that the good news would fill volumes. The ratio of landed planes to crashed ones is extremely high, yet all one can think about is the crashes.

Penn Jillette had a wonderful example in a recent video. He had a blemish on his nose, and noted that even though the blemish covers a very small portion of his enormous body, it is all you can look at and think about.

We forget the common and focus on the differences. That focusing is often so misconstrued as to be proclaimed an impossibility, or at least a highly unlikely chance occurrence.

Shit Happens
We experience coincidences all the time. It’s mostly a matter of perception; you have to think about things in a wider context. Think about how often the thing occurs as opposed to how many times it doesn’t.

And stop attributing your own ignorance to an invisible entity.

Watch this: What are the odds that you, reading this right now, have a brother named Bill and are wearing a blue shirt?

What a coincidence!

-STA