A nescire ad non esse
A nescire ad non esse ( Latin for "from not knowing to not being") describes a rhetorical figure that is one of the ad-populum arguments. An assertion that something is not the case is justified by the fact that the facts are not known (e.g. "It cannot be like this, (because) I have never heard it like this"). But it is not a logically valid argument; if so treated, it produces a fallacy .