A type of fallacious argument in which the attempt is made to refute a theory or belief by discrediting the person(s) who advocate that theory or belief; an ad hominem argument.
ipsedixitism
noun
An unfounded, false and dogmatic assertion; an ipse dixit.
How often have the words argumentum ad hominem and ipsedixitism occurred in a corpus of books? (source: Google Ngram Viewer )