To be more specific, economists are no better than fortune tellers when trying to make short-run macroeconomic forecasts. Heck, if we actually knew what was going to happen over the next 12 months, we'd all be billionaires.
But we can (on occasion) make sensible predictions about the long-run impact of various government policies. All other things being equal, for instance, it's safe to say that countries with bigger governments will grow slower than nations that don't divert as many resources from the private sector. Even the World Bank and European Central Bank agree with that common-sense proposition.
Another can't-fail prediction is that bailouts will reward bad behavior and lead to dependency. That's why I'm not at all surprised by the news that Greece will get another bailout.