The lecture is part of the graduate courses “Master of Science in International Horticulture” and “Water Resources and Environmental Management”. It deals with central debates in 20th Century philosophical reasoning about science. More specifically, the positions of inductivism, deductivism, paradigm theory, and systematicity theory are discussed. The students of the above-mentioned MA programmes have to classify their own research approaches according to the theoretical frameworks discussed in the practical exercises part of the lecture. Literature: Chalmers, Alan F. (1999): What is This Thing Called Science? Third ed. St. Lucia: University of Queensland Press.