We describe and analyze an important cognitive obstacle in inter- and intra-community ar-gumentation processes, which we propose to call 'Cognitive Systemic Dichotomization'. This social phenomenon consists in the collective use of shared cognitive patterns based upon dichotomous schemati-zation of knowledge, values, and affection. We discuss the formative role of CSD on a community’s collec-tive cognition, identity, and public discourse, as well as the challenges it raises to reasoned argumentation, and how different approaches to argumentation undertake to face this obstacle to (...) the reasonable debate of issues of public concern. (shrink)