This article provides a theoretical and philosophical investigation for the discursive construction of truth based predominantly upon the discourse theory of Laclau and Mouffe but also on insights drawn from other scholars. As a theoretical article the aim is to contribute to the understanding of post-truth as a recent phenomenon and elaborate on several dimensions and aspects of it by employing a conceptual analysis enriched with several references from recent literature and published articles. Social truth as a social construction is a discourse with a privileged signification power over masses. Therefore the conditions for the construction of the discourse of truth are a focal topic for analysis. On the other hand, the ‘post-truth’ concept, which invaded in political life during 2016, puts into contestation several constitutive and structural elements of truth and consequently democracy as it currently functions in modern liberal states. The article is divided into three sections: (1) The first section provides a theoretical analysis on what is truth and how it is constructed as a discourse in a society; (2) the second section discusses the concept of post-truth and the possible reasons for the emergence of post-truth narratives in contemporary political communication and (3) the last section delineates the impact that post-truth narratives have on the political level, the institutional level and the social level.