What the Post Hoc?
The Post Hoc fallacy derives its name from the Latin phrase “Post hoc, ergo propter hoc.” This has been traditionally interpreted as meaning “After this, therefore because of this.” This fallacy is committed when it is concluded that one event causes another simply because the proposed cause occurred before the proposed effect. This is the very reason why two events being highly correlated does not mean one caused the other. There could be a third factor which causes the other two events to occur. The two events might be related as cause-and-effect, but typically you need more than just a coincidence that the two things occurred at the same time. A great analogy to make this point comes from one of my favorite books about teaching philosophy principles through jokes “Plato and a Platypus Walk into a Bar . . .”. Here you go:
Ninety-year-old man meets a beautiful young blonde in her mid-20s and decides to marry her against his family’s best advice. Nine months later his young wife tells him that she is pregnant. The old man proudly marches in to see his doctor and announces the “good news”. The doctor looking at the old man smiles and says, “I want to tell you a story… A man wakes up in the morning in a hurry to go bear hunting and as he leaves his home instead of grabbing his shotgun, he grabs his cane. While out in the woods he comes upon a bear, raises his cane up, aims it at the bear and attempts to pull the trigger. Immediately at that point, there is a loud bang and the bear drops over dead. The doctor looks at the old man and asks, “what do you think happened?” The old man replies, “why somebody else shot the bear. ” The doctor quickly quips, “my point exactly”.
Need I say more?