But the currency union and how it is organized also matter. Krugman compares Poland Versus Greece 09/11/2015:
Consider, in particular, a comparison that should be made — between Greece and Poland. Poland, like Greece, is a country on Europe’s periphery, closely linked to the rest of the European economy. It’s also a country with relatively low productivity by northwestern European standards, indeed lower productivity than Greece by standard international measures: [he puts in a chart for illustration here]But the press in Europe and the US from what I've seen rarely talks about real problems of a currency zone, including things like how it can force "real devaluation" in parts of the union.
But Poland has not had a Greek-style crisis, or indeed any crisis at all. Instead, it has powered through the turmoil of recent years: [another chart]
What’s the difference? The main answer, surely, is the euro: by adopting the euro Greece first brought on massive capital inflows, then found itself in a trap, unable to achieve the needed real devaluation without incredibly costly deflation.
Every time someone asserts that the Greek problem is really on the supply side, you should ask, not whether it has supply-side problems — it does — but why this should lead to collapse. Greece seems to have about 60 percent of Germany’s productivity, which means that it should have real wages only about 60 percent as high as Germany’s. It should not have 25 percent unemployment. [my emphasis]