Victor Klemperer (18811960) was a German Professor of Romance Languages who became famous especially for the writings in which he related how the Nazis deformed the German language to the extent of developing what he called ‘the language of the Third Reich’. In this paper, I aim to explain what this language reveals about certainties understood in Wittgenstein’s sense, which in turn might also contribute to providing a more comprehensive view of the extent to which the language of the Third Reich was carefully designed to decisively influence Germans’ attitude and worldview. Specifically, I will address eight issues: the perversion of morality through a radically bipolarized message; the creation of a context in which all judgements should be given up; the use of two kinds of persuasion; the bias for overgeneralizing the spreading of certainties; the difficulty of assessing borderline cases of being certain; the propagandistic mistake ofcrying out alleged certainties; the emotional exclusion of doubt – paying particular attention to the realms of army and religion as well as to the use of slogans and superlatives; and the replacement of Nazi worldpictures.