* The Barber's Rule: The barber cuts everyone's hair *except* people who cut their own hair.
* The Question: Does the barber cut his own hair?
The Paradox:
* If the barber cuts his own hair: He violates his own rule, because he's cutting the hair of someone who cuts their own hair.
* If the barber doesn't cut his own hair: He must be cut by someone else, but that would mean he cuts the hair of someone who doesn't cut their own hair, again violating his rule.
The Solution:
This is a paradox because it creates a situation where both possibilities lead to a contradiction. The barber's rule is logically impossible to fulfill.
The puzzle highlights the dangers of self-referential statements in logic.