This short, concrete, and to-the-point book guides students through this vast field of conflicting opinions. The book begins from the premise that students benefit most from seeing a balanced treatment of all available views. For instance, this book provides coverage of both <i>ad hoc</i> and optimizing models. It also explores divisions such as flexible price versus sticky price models, rationality versus irrationality, and calibration versus statistical inference. By giving consideration to each of these 'mini debates;, this book shows how each approach has its good and bad points.