The current financial crisis was precipitated by a bubble in the US housing market. In some ways it resembles other crises that have occurred since the end of the second world war at intervals ranging from four to 10 years.
However, there is a profound difference: the current crisis marks the end of an era of credit expansion based on the dollar as the international reserve currency. The periodic crises were part of a larger boom-bust process. The current crisis is the culmination of a super-boom that has lasted for more than 60 years.
Boom-bust processes usually revolve around credit and always involve a bias or misconception. This is usually a failure to recognise a reflexive, circular connection between the willingness to lend and the value of the collateral. Ease of credit generates demand that pushes up the value of property, which in turn increases the amount of credit available. A bubble starts when people buy houses in the expectation that they can refinance their mortgages at a profit. The recent US housing boom is a case in point. The 60-year super-boom is a more complicated case.