More stig:"The standard models (referred to earlier in the introduction, and discussed at greater length below) assume that the source of the disturbances to the economy is exogenous. To me, it is clear that that is simply wrong: the credit and housing bubble that were at the center of the 2008 crisis was created by the market. The bubble was a market phenomenon. To assume that it was exogenous is to assume that there is nothing that we can do either to prevent the creation of a bubble or to curtail its size."