During the Abbasid caliphate period, especially during the period of Ma'mun, there were debates with non-Muslims, whether from the Ahl al-Kitab (People of the Book) or others, which, according to some of the authors, illustrate a brilliant era and free-thinking of Ma'mun and his belief in plurality of ideologies. But the analysis of the actions and dialogues of the caliph and debaters indicates another situation. This research, based on the qualitative method of interpretation (based on description and analysis), seeks to investigate the question that which space has dominated over debaters, especially non-Muslims, and how much they practiced self-censorship in expressing their beliefs and what has been the effect of the presence of Ma'mun in these debates. The present paper claims that, with regard to the encounters of the caliph with the debaters, the aim of these meetings was to overcome and suppress these groups with the aim of gaining the intellectual victory of Muslim over them.