自相矛盾

You can use it as an adjective or a verb. Most people use it to describe a person's behavior. You might say, 'Your words are zì xiāng máo dùn.' It works perfectly when someone changes their story. Or when their lifestyle does not match their advice. It is a punchy way to point out a logic fail. Just be careful not to sound too accusatory!

Use it when you spot a blatant hypocrisy. Use it in a meeting when a plan lacks logic. It is great for texting a friend who says they are 'broke' while buying a new iPhone. You can use it in academic writing to critique an argument. It is a very common way to describe political flip-flopping. It sounds smart but is easy to understand.

Do not use it for simple mistakes. If someone just forgot a fact, it is not a contradiction. Avoid using it during a heated argument with your partner. It might sound a bit too 'intellectual' or cold. Do not use it for physical accidents. It is strictly for logic, statements, or intentional actions. If you use it for a clumsy person, people will be confused.

This phrase comes from a famous philosopher named Han Fei. He lived over 2,000 years ago. He used this story to teach kings about consistency. The words for spear máo and shield dùn are still used today. In fact, the modern Chinese word for 'contradiction' is just máodùn. This idiom is the origin of that entire concept. It is one of the first stories Chinese children learn in school.

You will often hear people just say máodùn. That is the shortened, everyday version. If you want to be fancy, use the full four characters. Sometimes people say 'His logic is full of holes.' But zì xiāng máo dùn is the gold standard. It implies the person trapped themselves. No one else had to trip them up.