The topic of this talk is based on my year as a „Marsilius Fellow“ in the Marsilius-Kolleg of Heidelberg University. The idea behind the Marsilius Kolleg is to bridge the gap between sciences and humanities through meetings, discussions and joint projects, which in turn promote understanding and cooperation between the sciences and the humanities. Founded in 2007, the Marsilius Kolleg is a central component of Heidelberg University’s successful proposal granted by the Excellence Initiative, launched by the federal and state governments of Germany. My Marsilius project was entitled „Wissen, Glaube(n), Aberglaube“ [knowledge, belief, superstition], together with a sociologist and a historian/theologist we addressed different facets of this theme. At this year's ARI christmas colloquium I will discuss various aspects of the simple-sounding question: "What is science?“, based largely on the book "Systematicity – The Nature of Science“ by Paul Hoyningen-Huene. I will try to define science and to demarcate it from non-science and pseudo-science.