environment: A system is a set of elements, which are determined as cohesive from an observer's perspective. Their relations to each other differ quantitatively and/or qualitatively from those to other entities. These observed differences allow to constitute a system border, distinguishing the system from its environment. He concludes that it depends on these criteria and the observations made by the observing persons, whether systems can be identified or not. Criticism and counter-criticism – loss of truth and "fake news" Constructivist positions are accused with being "blind to the difference between truth and lies." It is problematized that truths only seem to exist in the plural and that the associated task of distinguishing between lies and truth is "dangerous on the one hand and inappropriate on the other". Kraus takes a detailed look at this problem at various points and, using recourse to philosophical discourses of truth, clarifies that a distinction must first be made between "truth" and "truthfulness" and that the opposite of "truth" is not the "lie" but the "Falsehood". The counterpart of "truthfulness", on the other hand, is the category of "lies". So there are the following comparisons: truth - falsehood and truthfulness - lie. Based on this, Kraus defines lie as a contradiction to the subjective belief that it is true. A person's statement is considered a lie if it contradicts their own thinking of it as true. Then he differentiates between lies (as deliberate false statements) and errors (as subjective thinking of something as true that is judged as not true or false). He also clarifies that it can only be decided from observer positions whether a statement is true or false, but that these decisions cannot be made arbitrarily, but must be reasonably justified. In this respect, there can be no objective truth from the perspective of a constructivist epistemology, but it is still possible to justify when a statement should be considered true in terms of consensus and/or coherence. Kraus claims that with this approach, it is also constructivistically possible to make a well-founded decision about the difference between news and fake news. Literature Kraus, Björn (2014): Introducing a model for analyzing the possibilities of power, help and control. In: Social Work and Society. International Online Journal. Retrieved 3 April 2019. (http://www.socwork.net/sws/article/view/393) Kraus, Björn (2015): The Life We Live and the Life We Experience: Introducing the Epistemological Difference between "Lifeworld" (Lebenswelt) and "Life Conditions"