One cannot separate the issue of economic prosperity from politics e.g. as the renowned economists, Besley and Persson have shown, greater `state capacity' allows for a more efficient collection of taxation and so an increased state capacity in the future. Efficient tax raising ability enables more investment in productive public capital (e.g. better rule of law, and more productive citizens via more efficient public administration (including law enforcement and tax collection), health, education, transport and housing investments) and so more efficient tax raising in the future. We undoubtedly live in a world where the capacity of states has been diminished by the growth of large and multinational corporations that are expert at playing one country off against another, avoiding taxation and evading regulations. Thus if the euro is part of a cooperative process that allows for the creation of greater state capacity in Europe and so the greater ability to collect taxes from large and/or internationally mobile corporations then these potential gains can be compared to the evident present day costs of e.g. high levels of unemployment in many euro member states. However, if this is the justification, then I don't see, from a practical as well as social welfare perspective, why a cooperative process doesn't do more to compensate the losers e.g. via transfers/investments within and across countries and within and across generations.