Monetary policy inertia and the paradox of flexibility
本摘要源自该文的 英格兰银行 工作论文版（2020），正式发表版可能有调整。
This paper revisits the paradox of flexibility, ie, the result that, in a liquidity trap, greater price flexibility amplifies output volatility in response to negative demand shocks. We argue this paradox is the consequence of a failure of standard models to correctly characterise monetary policy and that allowing for a smooth adjustment of the shadow policy rate eliminates the paradox and produces output responses to a negative demand shock that are in line with those under optimal monetary policy. The reason is that, under an inertial policy, a decline in the shadow rate implies that the future actual policy rate will remain relatively low, which increases expectations about the economic outlook and inflation. The rise in inflation expectations reduces the real rate, thereby sustaining real activity. As we raise the degree of price flexibility, a negative demand shock causes a sharper fall in the shadow rate and increase in inflation expectations, which leads to a more significant drop in the real rate and, hence, a milder decline in the output gap.