The lie accompanies us, it is parasitic on the truth and indispensable in our everyday life. But how can we limit it and prevent it from destroying the truth? This question is particularly topical given the so-called “post-truth” phenomenon of fake news, con-spiracy theories and populist propaganda. Arendt’s analyses of the relationship between truth and lies in politics are helpful. To defend facticity, truth is indispensable, but factual truth resists limitless freedom of speech and action, or, in Arendt’s words, our enlarged mentality. Imagination is the common ground for creativity, the design of another world, but also for lies. There-fore, politics and lies are structurally very close, though of course not the same. Contemporary populist movements use lies in order to undermine the credibility of other politicians and mass media. The boundaries between truth, lies, the denial of reality, invented truths as well as, for example, anti-Semitism and racism are dissolving. Conspiracy theories are the pinnacle of the loss of reality. In contrast to lies, they offer a closed parallel world in which nothing happens by accident and nothing is what it seems. Zygmunt Bauman’s term retrotopia indicates that globalization and technological change are leading to growing uncer-tainty and a discrediting of policies, which meet with populist aims. Arendt’s republicanism offers an alternative to both, popu-lism and consumer liberalism: the defense of facts, enlightened criticism and a concept of a qualitative plurality of engaged citizens.