Three New Lessons of the Euro Crisis  by Arvind Subramanian,
Peterson Institute for International Economics  Op-ed in Project
Syndicate April 8, 2013   While some observers argue that the
key lesson of the euro area's baptism by fire is that greater
fiscal and banking integration are needed to sustain the
currency union, many economists pointed this out even before the
euro's introduction in 1999. The real lessons of the euro crisis
lie elsewhere—and they are genuinely new and surprising.  The
received wisdom about currency unions was that their optimality
could be assessed on two grounds. First, were the regions to be
united similar or dissimilar in terms of their economies'
vulnerability to external shocks? The more similar the regions,
the more optimal the resulting currency area, because policy
responses could be applied uniformly across its entire
territory.  If economic structures were dissimilar, then the
second criterion became critical: Were arrangements in place to
adjust to asymmetric shocks? The t