The phrase "bear one out" refers to the act of supporting or validating someone's claims or opinions. Its antonyms would include "challenge," "contradict," "disprove," "oppose," "refute," and "discredit." When we challenge someone's statements, we are expressing disagreement or doubt. Contradicting someone means pointing out inconsistencies or arguing against their assertions. Disproving someone's claims would involve demonstrating their errors or falsehoods. Opposing someone can mean taking a contrary position or resisting their arguments. Refuting someone's claims involves presenting evidence that undermines their assertions. And finally, discrediting someone means casting doubt on their credibility, authority, or reliability.