This volume brings together the lectures presented at the 5th Metaphysics of Science Workshop held from June 2 to 3, 2005, in Ghent, Belgium. The aim of this volume is twofold. First, it fields a selection of ongoing discussions on a central topic in contemporary analytical metaphysics. Authors were asked to encapsulate their lecture topic into a prcis, highlighting the contesting views, accentuating the pro and contra of the main arguments, and shedding light on the origin, the evolution and the eventual offspring of a respective discussion. Second, this volume addresses the methodological question by examining what can be learned if we compare these discussions from a methodological perspective. What are the red herrings and shortcomings? Is an integrated methodology possible? Does each discussion finally await a pluralism of plausible positions or will an overall convincing account be expected? And finally, can analytical metaphysics methodologically assert and investigate their basic assumptions, if not from a common sense stance?