paralogism
A fallacious argument or illogical conclusion, especially one committed by mistake, or believed by the speaker to be logical.
Which is a Paralogism not admittible; a fallacy that dwels not in a cloud, and needs not the Sun to scatter it.
Where it comes from
Borrowed from Middle French paralogisme, from Late Latin paralogismus, from Ancient Greek παραλογισμός (paralogismós).
Adapted from the Wiktionary entry paralogism (CC BY-SA 4.0).