The relativisation of truth and the blurring of the boundaries between truth and falsehood in the public sphere are nowadays positioned in media discourse and academic literature as a normal historical process and described by the term “post-truth”. The author proposes to subject its correctness and heuristic value to careful critical analysis. “Post-truth” according to the author denotes a fundamentally important essential substitution: truth in it is stripped of its absolute status and placed in the same line with things temporary, finite, conventional – post-communism, post-totalitarianism, post-modernism, post-secularism, etc. Therefore, the author calls to avoid the term “post-truth” since it contains not only a logical, but also an ontological error.