This volume provides the critical edition and English translation of questions 16 of the Prologue of Alnwick's commentary on the Sentences and of the two questions de scientia, which are directly connected to the Prologue. The fundamental content of these questions is analysed within the context of the complexity of Alnwick's thought and of his cultural background. The edition also offers a full introduction and bibliography as well as extensive indexes to manuscripts, names, concepts and subjects. It shows that William was indebted to, among others, Giles of Rome, Godfrey of Fontaines, Gonsalvus of Spain, Henry of Ghent, John Duns Scotus, John of Reading, Robert of Cowton, Thomas Aquinas and William of Ware. He was also indirectly influenced by Henry of Harclay and William of Nottingham. The edition derives from the research project 'Le trasformazioni dello statuto scientifico della teologia agli inizi del XIV secolo: il caso di Guglielmo di Alnwick, socius di Giovanni Duns Scoto e vescovo di Giovinazzo', ended in 2012 at the University of Bari 'Aldo Moro', in collaboration with the Town of Giovinazzo.