Greenspan actively advocated for more use of ARM mortgages for personal home buying, while in a position to have the best access to data and analysis on the growing risk of those mortgages. Whereas mere common sense and a knowledge of economic history would argue against widespread use of ARMs for individual home purchases. When the fed chair says “we need more ARMs” to a market using ARMs to prop up a growing bubble, that is as much or more responsibility as any other single person.