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The post hoc fallacy is a widespread logical fallacy. Post hoc fallacy examples abound everywhere around us, and especially on the internet – where all fallacies are exposed sooner or later!

The full name of this fallacy is post hoc ergo propter hoc, which means “after this, therefore because of this” in Latin. In simple terms, a post hoc fallacy is one where when two events happen soon after each other, the occurrence of the second is attributed to the first.

Post Hoc Fallacies: a Search for Answers

Most post hoc fallacy examples occur when one encounters unknown events. The urgency to discover an explanation can easily mislead one to accept such fanciful solutions.

A typical post hoc fallacy example is every superstition you might believe in. If you see a black cat or pass under a ladder and then later in the day you break a glass or slip and fall, you might tend to attribute the accident to the (entirely irrelevant) earlier occurrence. “Seeing the black cat brought bad luck, that’s why I broke the glass”. Every form of a cargo cult process is essentially a post hoc fallacy.

Also notice how post hoc fallacies are examples of confirmation bias. In other words, you tend to notice the one occasion where you broke a glass after seeing a black cat, but ignore the countless other ones where seeing an innocent kitten caused no harm.

Some More Post Hoc Fallacy Examples

For most people, seeing a black cat would not be connected with an unhappy incident occurring later.

On the opposite side, some events do happen because of prior events. If you use butter while cooking and then later you accidentally drop a glass, the post hoc ergo propter hoc sequence is correct. Your hands got greasy, you didn’t wash them, and as a result you couldn’t get a good grip on the glass.

The fun begins with some post hoc fallacy examples that don’t seem to be fallacies. In other words, there are events that repetitively and demonstrably occur after some other events, though there is no reasonable linkage between them.

The most famous post hoc fallacy example of this kind is the car that didn’t like vanilla ice-cream.

Ambiguous Post Hoc Fallacy Examples: the Car that Didn’t Like Vanilla

The story has been going around the internet for a very long time. Personally I doubt its authenticity, but that’s irrelevant for our purposes, which is how post hoc fallacy examples can sometimes be ambiguous. That is, they can reveal an actual event hidden behind the fallacy.

As the story goes, a man complained to the car company that his new car didn’t start when he went to the store to get vanilla ice-cream, but it had no problem starting with other flavors.

Though skeptical, the company sent an engineer. To the engineer’s surprise, it turned out to be true! Every time the man got vanilla ice-cream, the car wouldn’t start. All other flavors caused no such problem.

Of course the engineer didn’t really believe the flavor choice was the problem. Eventually, he realized that getting the vanilla ice-cream took less time, as the freezer containing it was easier to access.

Since the problem was pinpointed to time rather than flavor, it was easy to find the true culprit: vapor lock. The engine cooled down enough to start with other, more “time-taking” flavors, but with vanilla the engine was still too hot for the vapor lock to dissipate.

Post Hoc Fallacies: Resist the Easy Way Out

A post hoc fallacy can sometimes be hard to disprove – in that it reminds us of particularly sophisticated strawman fallacies. As the example above shows, it can appear to be valid. What, then, is the right way to detect post hoc fallacies?

First of all, resist the easy way out. It’s human nature to seek simple answers to complex problems, but more often than not a very simple answer is wrong or at least incomplete.

Sadly, our need to explain things is even more pressing with undesired events. Accidents or other sad occurrences feel awful. And so, you think, there has to be some explanation, right?

However, it’s very rare to explain something as a result of merely one thing. All events, happy or not, occur as a consequence of several complex factors. Even in their simplest, more-or-less true instances, post hoc ergo propter hoc sequences are only partly true.

The use of butter while cooking is a factor to your dropping the glass, but it’s not the only one. Not washing your hands is another, and so is the unique qualities of the glass – perhaps it was a particularly smooth, easy-to-drop model.