Many people blame overspending and low tax collection for Greece's current debt crisis. But the root causes of the calamity may be far darker: deception and bribery. The currency swap bets that Greece used to mask debt, including a controversial off-market swap with the help of Goldman Sachs (NYSE: GS), are just the tip of the iceberg.

Daniel Kaufmann told me that corruption could detract as much as 8% from Greece’s GDP -- while taking a similar toll on Italy and other EU nations. Kaufmann is a senior fellow at the Brookings Institution, the man behind the Kaufmann Governance Post blog, and the author of a new study that finds a correlation between fiscal deficits and corruption across developed countries. He was formerly a director at the World Bank Institute, leading work on governance and anti-corruption.

In part 2 of my interview with Kaufmann, he says that fixing Greece's long-term problems -- and the EU's -- comes down to managing corruption more effectively, and demonstrating fiscal prudence. Here is an edited version of our conversation:

Fool contributor Jennifer Schonberger does not own shares of any of the companies mentioned in this article. You can follow her on Twitter. The Motley Fool has a disclosure policy.