Is the ad hominem argument a fallacy or not? In this paper I will try to demonstrate that an ad hominem is not intrinsically fallacious and that the speaker\u2019s personal convictions, commitments and actions are deeply involved in every argument. This paper starts with a comparison between dialectical and rhetorical approaches to the argumentation, and, in particular, to the agreement. Briefly: from a dialectical standpoint, the argumentation is aimed at resolving a difference of opinion or a disagreement. On the other hand, from the rhetorical perspective argumentation also often deals with dialogues of the deaf, with incommensurable points of view. The agreement is a key concept of Perelman\u2019s and Olbrechts-Tyteca\u2019s new rhetoric. Agreement is not only what is ensured by the argumentative process. It is also the starting point of argumentation (prior argument): all argumentation must proceed from points of agreement (e. g. common values and hierarchies). These are aspects that would be agreed upon by the audience as conceived by the orator. Therefore, the audience is part of the arguments and we cannot divide the speaker, the subject on which he speaks and the hearer. In the last part of the paper, I focus on Perelman\u2019s and Olbrects-Tyteca\u2019s snowball interrelation between act and person \u2013 which mutually affect each other in the same direction \u2013 showing the role of ethos of both orator and audience in argument. Ad hominem argument represents an important testing ground because it expressly relates with personal conduct, character, motives, etc
