This doctoral thesis addresses a group of conceptual instruments that are central to Aristotle's philosophy, namely, the concepts of pros hen, homonymy, synonymy and multivocity. These instruments are crucial to many of Aristotle's works as he devotes himself to analysing the key notions in each of his investigations using these instruments. Despite the undisputable importance of these instruments, they display severe interpretative problems, which this thesis critically evaluates. The currently established view on the relationship between homonymy and multivocity is discussed (...) and then reassessed in order to approach the definition of the so-called pros hen structure. This approach takes into account a so-far undescribed distinction of types of examples Aristotle uses and sheds new light on the assessments of the role of the pros hen structure in Aristotle’s philosophy and the theories on development in Aristotle’s thought. Niels Tolkiehn studied Philosophy and Systematic Musicology at the University of Hamburg. He continued his studies as a doctoral student at the Munich School of Ancient Philosophy, a graduate school of the Ludwig-Maximilians-Universität München. Supervised by Prof. Dr. Christof Rapp, he was awarded his doctoral degree in 2019 with this dissertation. (shrink)