Essays in Dynamic Macroeconomics andPolitical EconomyInaugural-Dissertationzur Erlangung des Grades eines Doktorsder Wirtschafts- und Gesellschaftswissenschaftendurch dieRechts- und Staatswissenschaftliche Fakult atder Rheinischen Friedrich-Wilhelms-Universit at Bonnvorgelegt vonMarco M. Sorgeaus NapoliBonn 2012Dekan: Prof. Dr. Klaus SandmannErstreferent: Prof. Dr. Martin F. HellwigZweitreferent: Prof. Dr. Thomas HintermaierTag der mundlic hen Prufung: 20. Dezember 2011Diese Dissertation ist auf dem Hochschulschriftenserver der ULB Bonnhttp://hss.ulb.uni-bonn.de/diss online elektronisch publiziert. To Lucy and Viola AcknowledgementsThis thesis presents the main results of my research at the Bonn Graduate Schoolof Economics. I am indebted to a number of people who supported me and my workduring the past years.Firstly, I owe my most sincere gratitude to my Ph.D. advisors Prof. Martin F.Hellwig and Prof. Thomas Hintermaier for their excellent guidance and help when-ever I needed, and for the freedom they granted me to develop my own research ideas.The numerous comments and the fruitful discussions we had on the topics dealt within the present work, have been a constant source of inspiration. All errors, of course,are my own.I am very thankful to my co-authors Giuseppe Albanese and Francesco Carravettafor the excellent cooperation, and to Prof. Norbert Christopeit and Dr. Michael P.