This book is an attempt to provide a philosophical answer to the simple question, "What is the law?" as well as address the various debates this question has spawned. Along the way, it develops a unique position within analytic jurisprudence by carefully distinguishing between a theory of the nature of a legal system and a theory of the nature of legal content (that is, of individual laws). Finally, it applies the framework established in the first part of the book to two substantive areas within legal theory: legal reasoning and international legal systems. The result is a unique introduction to the philosophy of law, one that presents and tests a theory of analytic jurisprudence, while it introduces students and others to this sub-field of philosophy. It explains and clarifies for students the views of the most significant scholars in the philosophy of law—those of H.L.A. Hart, Hans Kelsen, Joseph Raz, Ronald Dworkin, and John Finnis—and offers a critique of each. This approach should appeal to all types of philosophers--students and scholars alike--who are wary of wading into the field of legal theory as well as philosophers of law who wouldn’t find useful or interesting a mere survey of the field.