Well, I think that the biggest uncertainty has been we just went through the worst recession since the Great Depression and people weren't sure whether the financial system was going to melt down and whether we were going to tip into a endless recession. So let's be clear about the sources of uncertainty in terms of business investment over the last several years: A huge contraction, trillions of dollars of losses in people's 401(k)s; people have a lot of debt coming out of the previous decade that they still haven't worked out; the housing market losing a whole bunch of value.