Why?

Paul Krugman writes:

Another Kind of Financial Fragility
February 4, 2011, 10:46 am

Recent events have a lot of economists working hard at trying to determine the causes of financial fragility — the vulnerability of some economies, ours very much included, to disruptive shocks that cause credit and spending to freeze.

"Trying to determine the causes of financial fragility." Really?

Here:

We think that red blood cells cause inflation. We think that white blood cells don't. We think we can take red cells out of your blood, and encourage you to grow more white cells. We think this will keep you good and healthy.

Then, when you get sick, we try to determine the cause of your "fragility."