<P>This book presents formalizations of three important medieval logical theories: supposition, consequence and obligations. These are based on innovative vantage points: supposition theories as algorithmic
hermeneutics, theories of consequence analyzed with tools borrowed from model-theory and two-dimensional semantics, and obligations as logical games. The analysis of medieval logic is relevant for the modern philosopher and
logician. This is the first book to render medieval logical theories accessible to the modern philosopher.</P>