Socrates: What is a tautology?
Pupil: A tautology is a self evident statement. The truth value of a tautology is always true.
Socrates: Excellent. Can you give me an example of a tautology?
Pupil: Water is wet.
Socrates: Nice try. But you are incorrect.
Pupil: Water isn’t wet?
Socrates: Not when it’s temperature is beneath zero degrees celcius or above 100 degrees celcius.
Pupil: And my mother pays you for this?
Socrates: My hourly rate just went up.