Passage Summary: Just because two things always happen together doesn't mean one is causing the other; they might both be caused by a third, hidden factor.

Reasoning: A consistent correlation between two things does not prove that one causes the other, as both could be effects of a single underlying cause.

Analysis: This is a classic lesson in 'correlation vs. causation.' The principle warns us against jumping to a causal conclusion just because two variables are linked. To apply this, look for a scenario where a causal claim is questioned or rejected because an alternative 'third factor' could be responsible for both observed phenomena. The correct application will likely involve someone correctly identifying that an association is not definitive proof of a direct causal link.