The theory behind this move – as espoused by Ben Bernanke, first as an academic, then as a Fed governor, and eventually as Fed Chairman – is that operating on the quantity dimension of the credit cycle is the functional equivalent of acting on the price side of the equation. That supposition liberated the Fed from fear of the dreaded “zero bound” that it was approaching in 2003-2004, when, in response to the collapse of the equity bubble, it lowered its benchmark policy rate to 1%.
这一变化背后的理论是&mdash;&mdash;由学者出身、后担任美联储董事、最后成为美联储主席的本·伯南克（Ben Bernanke）提出&mdash;&mdash;信用周期数量维度上的操作，其功能与在方程的价格端进行操作是等价的。这一论断使美联储不再担心其2003&mdash;2004年曾经接近过的令人畏惧的“零区间”。当时，面临股票泡沫崩溃的局面，美联储将其基准政策利率下降到1%。该理论指出，即使美联储不再有基点空间可用于降息，它仍然有足够的工具支持和指引实体经济。