The idea that governments necessarily have a critical role in economy and society is again plain since the global financial crisis. For 30 years, the democracies said that they were ineffectual in coordinating economic life, and markets were perfect for this political role. The report provides a corrective to the attendant policies based on these views, by using the Tobin tax, a proposal once again in the news, as an illustration. Through an interpretation of the ideal and less than ideal relations between governments and the financial sector, it assesses the Tobin tax. Criteria about its feasibility and desirability are drawn from this broader framework about the purposes of banks and their role in society. A Tobin tax on global financial transactions is a very modest reform, so modest that the vehement opposition by the financial sector could also be subject to interpretation.