People of today live in times where lying seems to be a “normal” tool of politics while at the same time political representatives declare themselves to be truth-tellers. Practices like inventing “counter-truths” are usual in authoritarian states as well as in populist movements or parties in democratic states. Hannah Arendt was the first political theorist after Niccolò Machiavelli to acknowledge the importance and the aftereffects of lying in the political realm. In my paper, I will, firstly, focus on how Arendt explained the origins, the impact, and the ambivalence of lying in politics in its different historical forms. Secondly, I will fol-low Arendt when she analyses the problem of how to know about what a lie is and if it undermines the political realm or if it is just a “normal” (occasional) lie which can be corrected by legal means. Thirdly, I will ask how we are measuring politics. Is politics about telling people the truth? Or are there other dimensions of acting in public that require attention? Here, too, I will start with the arguments Arendt elaborated in her essays. In the last part I will focus on the question of how to transfer Arendt’s reflections into the political realm of today. In the era of digital communication and digital warfare we must rethink Arendt’s reflections about how to counteract systematic lying. I will sum up with a couple of reflections about the means and forms of dealing with that kind of lying in politics: lying which undermines the political realm.