William of Ockham, the most prestigious philosopher of the fourteenth century, was a late Scholastic thinker who is regarded as the founder of Nominalism, the school of thought that denies that universals have any reality apart from the individual things signified by the universal or general term. Ockham's Summa Logicae was intended as a basic text in philosophy, but it's originality and scope encompass his whole system of philosophy. Yet the paucity of English translations and the structural complexity of the Latin have made the Summit, until now, almost completely inaccessible. Here Michael Loux has translated the first part of the Summa, one of the most original and influential medieval texts in logic. Preceding the translation are two essays: The first focuses on Ockham's ontology; the second deals with his theory of supposition. They are meant to introduce the reader to the central themes of Part I of the Summary, but, while introductory, these essays incorporate a controversial interpretation of Ockham which is intended to suggest a continuity between his philosophy and the work of contemporary analytic philosophy.