At present, as they claim, economists are generally guided by pragmatic considerations of what works not by formal definitions (2009: 231). This paper is aimed at sorting out this matter. We cannot refuse to reach at one (or a few) definition(s) of economics. This is another fundamental task of any philosophy of economics that cannot be ignored.
Though for some ears might sound paradoxical, after a wide exploration, I concluded that the wisest analysis on the definition and classification of economic sciences have been developed in the Nineteenth century by Mill, Menger and Neville Keynes, who are methodological precursors of economic science.
The paper will begin analyzing the thought of those methodological precursors, concluding with a proposal of classification of economic sciences combining their ideas. Then, it will sketch what have happened after them, during the Twentieth century. Third, it will show how a combination of different notions of rationality wider than the narrow already mentioned leaves room for the plurality of economic sciences stemming from the precursors ideas. Finally, the paper will derive from the different economic sciences the tasks that they should perform.