'post-truth' has become a buzzword for numerous current crises: the fragmentation of the media landscape, the ongoing debate about 'fake news', the loss of trust in science, etc. Although these crises take place in society, it is claimed that the roots of post-truth can be traced back to the history of philosophy. Occasionally, it is asserted that Karl Popper's critical rationalism gave rise to post-truth: His rejection of verificationism has limited truth claims in the realm of science. Given the absence of infallible evidence and certainty, critical rationalism calls for challenging scientific authority. I argue that post-truth is compatible with critical rationalism from an epistemological point of view, considering that both positions are critical of certainty. However, in critical rationalism, fallibilism, responsibility, and the idea of criticism are combined, and in this respect, it offers a possible way to overcome the problems that are associated with post-truth. This treatment of the problems of post-truth results from the recognition of moral responsibility to take action on the basis of a hypothesis that remains open to revision.