Arguments based on the beliefs and character of the audience are opposed to those based on the substance of the issue.

In classical rhetorical argumentation, the orator must not only know the case and the law, but also the judge, that is the people he or she intends to address and convince and the opponent he or she is going to face and refute. Before engaging in the quest for arguments, he or she must gather information about the ethos of the audience and of the opponent; that is about their beliefs, habits and general character, including their previous discourses and positions. The orator exploits this information either positively to confirm his or her position, or negatively to reject the opponent’s position:

— The ex datis argument positively exploits the natural ethos of the audience to infer a positive conclusion, S. Ex datis.
— The ad hominem argument exploits the information about the opponent’s discourses and beliefs in a negative way, by exhibiting their inconsistencies, S. Ad hominem.