These words refer to the rejection of a previous statement by argument or evidence. Contradict may indicate no more than disagreement with a statement: He flatly contradicted her assertion that he was too lazy to mow the lawn. In this case no attempt at proof may be involved. The word also applies to an obvious discrepancy between statements or things where no proof is necessary: parents who contradict each other when giving orders to their children.

• The findings of the two studies contradict each other; His voting record contradicts his claim to be a liberal.

In its widest application, deny can point to something refused or withheld: denying his request for a weekend pass; Substandard schools deny children the chance to learn. In the context of disputes, deny often suggests the specific situation of giving a negative answer to a charge or accusation: The treasurer hotly denied any misappropriation of funds.

Gainsay is a more formal word that is now rarely used in speech; it does suggest that someone gives vocal dissent to an opinion or accusation, perhaps arbitrarily tersely or abruptly, without supporting arguments: her habit of gainsaying anything he suggested. The word most often appears now with a negative: arguments for an appeal that not even the most cautious judge could gainsay ; new evidence that simply could not be gainsaid . Here, something is presented as so convincing or conclusive that an arbitrary rejection is not possible. Oppose is far less formal in tone than gainsay and applies widely beyond the context of dispute or argument. It can suggest unreasoning enmity to a position with no attempt to argue or present evidence: They still opposed the new theory despite all the corroborating facts mustered in its defence. Oppose can also suggest reasoned disagreement: the superior skill that his counsel revealed in opposing the prosecution’s arguments.

Contravene can function like contradict when it points to a discrepancy between statement or things, especially where one entity conflicts with another: No law can stand that contravenes the Consitution. In terms of argument, the word may point to an attempt to overthrow a whole trend of thought by making telling points: a speech in which he marshalled every available argument that might help him to contravene the objections to the bill’s passage.

The previous words are mainly concerned with situations in which one statement is at odds with another. The remaining words all can indicate the situation in which a statement or position is demolished by facts or evidence. Disprove is the most forceful of these, indicating that a statement, proposition, theory or even something accepted as a fact has been demonstrated as untrue by countering evidence: explorers who disproved the notion that the world was flat; he denied her assertion, but couldn’t disprove it. When two scientific theories contradict each other, for example, further investigation will disprove one or the other or both, whether in whole or in part. Controvert , a more formal word, points to someone who apposes a given view and wishes to disprove it by offering evidence: His opponents searched the data given in his report, hoping to find inconsistencies by which they could controvert his findings. When contrasted with contravene , the emphasis of controvert falls more heavily on controvert them. Refute can suggest the successful demolishing of an argument by reasoning alone but it applies even more forcefully when supporting evidence is suggested: They refuted his claim of innocence with eyewitness testimony.