"Every time you find yourself saying that there must be some causal relationship between two strongly correlated variables, you should go back and look at this graph:"

Megan
elaborates.
Now remember to apply your knowledge in everyday situations:

Uncertainty! Skepticism! Modest knowledge claims! Them's the rubs.
Or to borrow from J.S. Mill's
Utilitarianism:
It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied. And if the fool, or the pig, are of a different opinion, it is because they only know their own side of the question. The other party to the comparison knows both sides.