The post hoc fallacy (from the Latin post hoc ergo propter hoc, which means “after this, therefore because of this”) is a logical fallacy in which someone assumes that because one event occurred after another, the second event must have been caused by the first (without any additional evidence of causality).
Humans are naturally inquisitive creatures. We’re always looking for the root of problems. However, if we are not cautious, we may incorrectly attribute the causes of events to things that were not the factors.
A real-Life example of the post hoc fallacy
The legendary Brazilian football player Pele once gave his game shirt to a fan, and soon after, his playing performance started deteriorating.
He believed it was because he lost his beloved shirt, so he instructed his friend to find it. And, after the shirt was returned to him, his playing performance did indeed recover.
It would certainly appear that Pele’s poor performance was caused by this particular shirt. However, what his friend didn’t tell him was that they couldn’t find the original shirt, so they returned with just another shirt.
Other examples of the post hoc fallacy
- An example of the post hoc ergo propter hoc fallacy is the claim that if the rooster crowed immediately before the sun rose, then that means that the rooster caused the sun to rise.
- If we purchased a rabbit’s foot as a good luck charm and later received a promotion at work, we might assume that the rabbit’s foot was the cause of the promotion. It’s somewhat understandable why we jump to this conclusion given that we’ve been trained to always seek out the simplest or most convenient explanation for why something happened.
- Another example of the post hoc fallacy might be: ‘Yesterday I ate blackberries, and today I have a stomach ache. The blackberries must have caused this stomach ache.’ While it is not out of the question for the blackberries to be the cause, the stomach ache might also be the result of something else.
- My wife must be driving the car incorrectly because we never had transmission problems until she drove the car.
- We prayed for a Mercedes and then got one. Prayer works!
- Henry received a vaccine and became ill. Therefore, the vaccine caused his illness.
- A sports fan sitting at home might notice that their favorite team did well whenever the fan drank lemonade, which can cause the fan to believe that them drinking lemonade at home helps their team do well in the field.
While It’s important to understand that there really might be a causal connection between these events, we cannot infer there is one merely because one event chronologically preceded another.
Why is post hoc a fallacy?
Post hoc is a fallacy because it suggests that one event happening before another necessarily means that the first event caused the second. If a person eats an ice cream on Tuesday and buys a winning lottery ticket on Wednesday, eating the ice cream did not necessarily cause them to win the lottery.
The post hoc fallacy can lead people to engage in superstitious thinking (also referred to as magical thinking), where they assume that coincidences and unrelated events are connected in a causal way, particularly as a result of supernatural influence.