A contradiction within oneself—holding statements or beliefs that are inconsistent.
彼の説明には自己矛盾があって、聞いていて混乱した。
There were contradictions in his explanation, and I was confused listening to it.
論文の中で自己矛盾を放置すると、査読で指摘されるだろう。
If you leave contradictions in your paper, peer reviewers will point them out.
発言と行動が一致しないと自己矛盾だと批判されることがある。
If words and actions don't match, one can be criticized for being self-contradictory.