A paradox is a statement or situation that seems self-contradictory or logically unacceptable but may in fact be true, or that reveals a deeper problem in reasoning. Paradoxes are important in philosophy, logic, and mathematics.

Famous paradoxes include the liar paradox ("This sentence is false"), Zeno's paradoxes of motion, and Russell's paradox in set theory. They challenge our assumptions, expose limits of language and logic, and often lead to new insights. Some paradoxes are resolved by clarifying concepts; others remain open problems.

Key points

• Self-contradictory statement or situation
• May be true or reveal a problem
• Famous examples: liar, Zeno, Russell
• Important in philosophy and logic