The ad hoc group "Facticity of the World", established in 2017, takes up the current discussion on "post-truth politics". The often conscious denial of reality in political discourse challenges science just as much as the negligent handling of truths. For it is precisely one of the tasks of science to inform the public about facts and connections, on the basis of which democratic decisions can only be made for the good of society. But how does science come to establish facts? Which authorities and processes decide this? And what is the relationship between what is once recognized as "true" and the task of science to contribute to progress by questioning previous assumptions? Against this background, the working group is to make transparent the methods of a critical, truth-oriented research that considers the constant revision of all levels of knowledge and examines their significance for processes of social shaping and transformation. To this end, the interdisciplinary exchange on procedures and methodology of knowledge acquisition as well as the public self-reflection of the natural, social and cultural sciences shall be intensified. In addition, processes of scientific criticism in the media, including "social media", will be investigated. The working group thus intends to contribute to the public debate on the importance of scientific knowledge, its authentication and its social binding power.