Under the conditions that prevailed then, and that prevail again now (high unemployment, low inflation, and near-zero interest rates), monetary expansion is relatively less effective, because it cannot push interest rates below zero. Moreover, firms are less likely to respond to easy money by investing in new physical capital and labor if they cannot sell what they already produce in the factories they already have with the workers they already employ.
约翰·希克斯（John Hicks）在曾经著名的1937年名为《凯恩斯先生与古典学派》的文章中清楚地解答了这个问题。在当时的情况下——现在也一样（高失业率、低通货膨胀及几近为零的利率），货币扩张相对没那么有效，因为它不可能把利率推到零以下。此外，如果公司无法卖出已雇佣员工在自家工厂里生产出来的产品，它们也不大可能利用低价货币投资新的实物资本与劳动力。财政刺激在这些情况下相对会更有效一些，因为它能在无需抬高处于最低点的利率和不压抑私人企业需求（一般情况下则会）的情况下创造对商品的需求。