In this work, the author addressed an in-depth discussion about the truth and its different meanings, and why the truth is essential. He delves into the arguments about why and how to sustain truths that can be shared on the basis of good reasons, and in the face of the post-truth market. In the post-truth era, as truth is swept from the public scene, coexistence becomes impossible. This is due to the force of a power that destroys politics itself and imposes itself as domination on society. Faced with such a serious consequence, the criticism of post-truth is followed by the commitment to a politics of truth, necessary as a condition of democracy. What to do with the truth in political life is not just a problem for now. The Greeks already tackled it. It is convenient to look at them, and then, back, consider how a real commitment can be maintained in our current democracies.