Self-contradiction — when one's own statements, claims, or beliefs contradict each other; often pointed out as a logical inconsistency.
彼の論は自家撞着で、どの立場を支持しているのか分からない。
His argument is self-contradictory, so it's unclear which position he supports.
その政策は言葉と行動が自家撞着していると批判された。
The policy was criticized for being self-contradictory between words and actions.