Of course, the euro was never entirely about economics. European leaders believed the single currency was a big step toward creating an irrevocable alliance among countries on the continent. But many experts warned that it could make its members less stable unless it was followed by a tighter political and budgetary union. Since that did not happen, the currency union was left fully vulnerable to economic crises and to the will of Europe’s more powerful economies.

Image The euro was celebrated when it was introduced in 1999. Credit... Ulrich Baumgarten/Getty Images

All those fears have played out in Greece, even as the threat of exits from the euro hangs over other weakened countries, like Italy, Portugal and Spain. Senior leaders in Germany, Finland and Slovakia who have publicly suggested a Greek exit seem to think it would scare weaker economies into accepting more austerity. That may not be necessary; some radical parties in those countries are already openly talking about leaving the euro.

The question now is what is the cost of leaving? Can a modern economy withstand the immediate damage of an abrupt currency change if the benefits of devaluation and regaining full control over fiscal and monetary policies could be limited and could take years to realize?

For example, returning to the drachma, which would trade at a deep discount to the euro, could help the Greek economy by making its island resorts, olive oil and feta cheese cheaper for tourists and foreign buyers. The country would also be able to control its own monetary policy, by pumping more money into the economy to stimulate lending rather than relying on the European Central Bank, which until recently has done too little.

But leaving the euro would mean few foreign institutions and investors would be willing to lend to the government, possibly for many years after exit. That could make it harder for the Greek government to buy essential imports like medicines, oil and gas. The financial system would most likely collapse under the strain of bank runs. Many Greeks fear that a return to the drachma could also lead to runaway inflation if the country’s central bank prints too many drachmas to prop up the economy. And that doesn’t even account for logistical challenges like redenominating contracts and printing new paper currency.