Brad DeLong on Larry White

…our models for why the risk discount has taken such a huge upward leap in the past year and a half are little better than simple handwaving and just-so stories. Our current financial crisis remains largely a mystery: a $2 trillion impulse in lost value of securitized mortgages has set in motion a financial accelerator that we do not understand at any deep level that has led to ten times the total losses in financial wealth of the impulse.

Thus my dissatisfaction with Larry White’s piece: he talks only about the impulse, while it is the propagation mechanism-the financial accelerator-that is the important part of the story.  $2 trillion shocks to global wealth do, after all, happen every several years, everytime there is a recession or a big rise in the prices of natural resources. But financial distress of the magnitude we see today happens once a century. Since the Bank of England developed its lender of last resort doctrine in the 1830s, we have only had two episodes this bad: the Great Depression and today.

Here is the whole essay, interesting throughout.  Brad is also blogging parts of the General Theory over at delong.typepad.com.

Addendum: Arnold comments; I think Brad’s short essay is so far the single best thing written on the crisis.