Correlation Does Not Imply Causation

Why does correlation not imply causation? In other words, why would two things which very much appear to be related, have no connection whatsoever?

The correlation = cause logical fallacy is the claim that two events which occur together must have a cause-and-effect relationship. It is also known as the cum hoc ergo propter hoc fallacy (In Latin, “with this, therefore before this”).

Let us turn to television for a clear illustration of this principle.

In The Simpsons’ episode Much Apu About Nothing, Ned Flanders spots a bear on the street, which prompts the whole town to crusade against bears and to create a so-called Bear Patrol.

Homer: Not a bear in sight. The Bear Patrol must be working like a charm.
Lisa: That’s specious reasoning, Dad.
Homer: Thank you, dear.
Lisa: By your logic I could claim that this rock keeps tigers away.
Homer: Oh, how does it work?
Lisa: It doesn’t work.
Homer: Uh-huh.
Lisa: It’s just a stupid rock.
Homer: Uh-huh.
Lisa: But I don’t see any tigers around, do you?
[Homer thinks for a while, then pulls out some money]
Homer: Lisa, I want to buy your rock.
[Lisa refuses at first, then gives up and takes the exchange]