Argument from ignorance (from Latin: argumentum ad ignorantiam), also known as appeal to ignorance (in which ignorance represents "a lack of contrary evidence"), is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false or a proposition is false because it has not yet been proven true.

Roger Bacon was born in Ilchester in Somerset, England, in the early 13th century, although his date of birth is sometimes narrowed down to c. 1210, "1213 or 1214", or "1215". However, modern scholars tend to argue for the date of c. 1220, but there are disagreements on this. The only source for his birth date is a statement from his 1267 Opus Tertium that "forty years have …