We have created a definition of untruth using a variation of the definition of truth.

untruth: (noun) a judgment, proposition, or idea that is not true but has bolstered credibility because of unending debate

Two thousand years ago, it was almost universally accepted that the world was flat. Iif someone today claimed the same thing, most people would just laugh it off and move on. Why? Because there is overwhelming evidence that the world is not flat. If we continue debating the flatness of the world even in the face of overwhelming evidence, we have created an untruth. It seems harmless and trivial, but it has a serious negative side effect: anyone that does not know better might interpret this unending debate as a sign that the jury is still out on the flatness of the Earth. They would be misinformed and we would be at fault for allowing such misinformation to spread.