In this paper, I discuss the current thesis on the modern origin of the <i>ad hominem</i>-argument, by analysing the Aristotelian conception of it. In view of the recent accounts which consider it a relative argument, i.e., acceptable only by the particular respondent, I maintain that there are two Aristotelian versions of the <i>ad hominem</i>, that have identifiable characteristics, and both correspond to the standard variants distinguished in the contemporary treatments of the famous informal fallacy: the abusive and the circumstancial or <i>tu quoque</i> types. I propose to reconstruct the two Aristotelian versions (see sections 1 and 2), which have been recognized again in the ninteenth century (sec. 3). Finally, I examine whether or not it was considered as a fallacious dialogue device by Aristotle and by A. Schopenhauer (sec. 4).Facultad de Humanidades y Ciencias de la Educación