The notion of 'freedom' has gained an emblematic character in contemporary political discourse. It is, commonly, viewed as the central value and political goal of modern societies. Similarly, human rights documents conceive of freedom as their founding principle with universal validity. In contradistinction to this prevalent approach to freedom, this paper aims to demonstrate that freedom is, primarily, a political signifier with social-historical variability. One cannot, therefore, simply and uncritically assume that freedom has (or should have) universal validity or transhistorical significance. In the first section of this paper, the structure of the contemporary liberal discourse on freedom is discussed and called into question. In light of Arendt's interpretation of freedom and through her analysis of the public domain, I reflect on the social-historical variability of the meaning of freedom and its inextricable nexus with a particular form of society. In the second section and drawing on Castoriadis, the notion of 'freedom' is approached in view of human signifying practices and the imaginary dimensions of society. This examination reveals in what way freedom––in the sense of a central social imaginary signification––contributes to the institution of an autonomous mode of society and determines the affective disposition and intentional vector of its inhabitants.