Something self-contradictory holds two ideas that cannot both be true at the same time — it argues with itself. “We never lie,” said by someone who has just lied, is self-contradictory. A plan can be self-contradictory if step one undoes step two. The self- here is not a person having feelings; it is the statement, the story, or the rule that does not sit with its own other half. Though actually, in everyday talk people also say “that contradicts itself” or “you’re contradicting yourself,” which is the same idea in looser clothes. Self-contradictory is the neater, more written label. It is stronger than “a bit mixed.” If two things merely sit awkwardly together, they may be in tension. Self-contradictory means they cannot both stand.