Post hoc ergo propter hoc is Latin for, ”after this therefore because of this”.
“the logical fallacy of believing that temporal succession implies a causal relation” Dictionary.com
This fallacy takes place when a person comes to a conclusion based solely on a proceeding event. In other words one might conclude that a rooster crowing causes the sun to rise simply because the sun rises after the rooster crows.
Example of post hoc ergo propter hoc
I might notice that every time I get into a checkout line at the supermarket, the line takes longer than all the other lines. Should I conclude that my mere presence in the line causes the checker to move slower? No. Perhaps I am a poor judge of which line is the fastest. Either way, if you see me in a checkout line, you would be safe to pick a different line to stand in.
It’s important to mention that just because someone uses this fallacy in an argument does not immediately mean their conclusion is false. It simply means the burden is on them to provide more convincing reasoning if they want you to be persuaded.
Disarming the post hoc ergo propter hoc
Some might be wondering how one is to refute or deal with a post hoc ergo propter hoc argument. It’s pretty simple
- Point out the fallacy – Sometimes this step is offensive. Use some tact. They need to realize that there conclusion doesn’t necessarily follow from whatever proceeding event they are citing.
- Point out another conclusion that could be reached - In my example, I mentioned that every checkout line I stand in goes slow. By utilizing the post hoc ergo propter hoc fallacy, I concluded that my mere presence in a checkout line causes the line to move slower (I still think that’s true). What other reasons could there be for this strange phenomenon? Could it be that I stink at selecting a fast line? Could it be that the checker is distracted by my stunning good looks? Could it be that I have waited too long between showers and a curious aroma is distracting my checker? All of these options are viable…ok, one of them is. Nonetheless, our friend committing the fallacy should be aware that other solutions or conclusions are available.
- Let them have the burden of proof – Let the person who is committing the post hoc ergo propter hoc fallacy know that there argument is not convincing. It is their job to support their argument with something more persuasive then the after this therefore because of this fallacy.
Here are other logical fallacy podcast mp3s ready for download.
Or check out the Youth Apologetics Training Podcast Archive.