The language ideology with concepts like monolingualism, uniformity, linguistic negationism is often recognizable in political and governance instruments. The intent of this paper is to trace the modern roots of those linguistic preconceptions that have interfered and continue to interfere in the study of multilingualism and its full social realization. Preconceptions still resistant to this day even to the obvious. As we do not have a historiographical intent, nor an encyclopedic one, it was decided to use the observation and comparison between two contemporary language policies yet geographically distant as the stimulus of our reflection: the NDEA (1958) of the United States of America and the European Cultural Convention (1954). The goal is to understand the cultural roots of the widespread monocultural ideology.