(also known as: post hoc [form of], regressive fallacy)
Description: Ascribing a cause where none exists in situations where natural fluctuations exist while failing to account for these natural fluctuations.
A occurred after B (although B naturally fluctuates).
Therefore, A caused B.
I had a real bad headache, then saw my doctor. Just by talking with him, my headache started to subside, and I was all better the next day. It was well worth the $200 visit fee.
Explanation: Headaches are a part of life, and naturally come and go on their own with varying degrees of pain. They regress to the mean, the “mean” being a normal state of no pain, on their own, with or without medical or chemical intervention. Had the person seen a gynecologist instead, the headache would have still subsided, and it would have been a much more interesting visit -- especially if he were a man.
After surgery, my wife was not doing too well -- she was in a lot of pain. I bought these magnetic wristbands that align with the body's natural vibrations to reduce the pain, and sure enough, a few days later the pain subsided! Thank you magic wristbands!
Explanation: It is normal to be in pain after any significant surgery. It is also normal for the pain to subside as the body heals -- this is the body regressing to the mean. Assuming the magic wristbands caused the pain relief and ignoring the regression back to the mean, is fallacious.
Exception: Of course, if the “cause” is explained as the natural regression to the mean, then in a way it is not fallacious.
My headache went away because that’s what headaches eventually do -- they are a temporary disruption in the normal function of a brain.