Like many of our readers, I watched in horror Thursday as the stock market melted down, trimming the Dow Jones Industrial Average by more than 500 points, erasing all of the year's gains. The conventional wisdom in the weeks leading up to the Congressional vote on the bill was that if the debt ceiling was not expanded, the nation would default on its debt and a national economic disaster would then follow. So, why would the stock market collapse after a deal was struck?