"In the beginning, at least for academics, there was philosophy. All of learned inquiry occurred within the discipline of philosophy and was carried out by philosophers. We retain the vestiges of this organization in our practice of awarding a single advanced academic degree, the Ph.D. or Doctor of Philosophy.’ As our understanding of the world around us grew, however, various areas of philosophy became sufficiently well understood to graduate into their own disciplines. Mathematics and the physical and biological sciences were the first to appear, followed more recently by the social sciences. Emerging as its own discipline is only the first step toward becoming a mature field of study. Economics is unique among the social sciences for the number of remaining steps it has taken. Unlike many social sciences, economics has a well-defined core set of methods. The first year graduate program in economics is virtually indistinguishable across American universities, consisting of microeconomics, macroeconomics and econometrics. As a result, economics can be easily defined by its tools of inquiry as by the target of its inquiry."