False Premise: When an argument (valid or not) is based on an assumption or incorrect statement.
Example: "Should Joe Biden and his son be investigated for their corrupt business dealings in Ukraine?"
However you answer this question, it requires accepting as fact that both Joe Biden and his son engaged in "corrupt business dealings" in Ukraine, despite a lack of evidence of such. It also glosses over an important distinction: Hunter Biden engaged in business in Ukraine as a private citizen, whereas the former vice president represented the U.S. government in his dealings with Ukraine. Conflating the two activities — or incorrectly suggesting the Bidens (father and son) did business in Ukraine together — makes this a false premise.
A deductive argument cannot be sound unless it is both valid (i.e., the conclusion follows from the premises), and all of the premises are true.
Learn more from the Internet Encyclopedia of Philosophy.