While the search for the essence of truth has its ancient record, the concept of post-truth is the most modern one. The concept of post-truth means situations in which facts have less influence on shaping public opinion than emotions and personal beliefs. New media, in particular social media and digital society, are an important medium nolens volens shaping reality. The existence of the notion of post-truth in the discourse, above all politicians, political scientists and media people, is beyond doubt. However, the very nature of this phenomenon is seen differently. When I started writing the text, I asked myself the following research questions: What are the features that define post-policy? To what extent does the concept of truth refer to a new phenomenon, and to what extent is it a new term for the phenomenon that has always accompanied politics and elections? What is the specificity of new media and the digital generation? Do they play the role of determinants or are they just a medium for shaping the post-truth process? Are modern elections digital or more information warfare? Looking for answers to these research questions, I will examine two cases of campaigns: the British Brexit campaign and the American presidential campaign Clinton-Trump. The text also undertakes an analysis of the post-truth phenomenon in the information war that has been taking place in eastern Ukraine since 2014.