I . T H E R I S K O F S T A G N A T I O N The COVID-19 virus has caused a negative supply shock to the world economy: global supply chains have been seriously disrupted, factories have been shut down, retail shops have also been closed. Social distancing measures adopted to contain contagion have also caused a severe reduction in demand. Unfortunately, the supply disruption caused by the virus is likely to be persistent, since firms may not be able to restart production for a while and, even when finally allowed to do so, they may not be able to rump up quickly. Workers will not return all at once, social distancing measures will likely disrupt production lines, global supply chains may have to be reconfigured and, in general, the costs of production and distribution are bound to go up. Furthermore, some companies will be forced into bankruptcy and their assets may not be recycled productively for some time. As explained by Fornaro and Wolf, absent aggressive monetary and fiscal policy interventions such a persistent disruption of supply may ‘cause a demand-driven slump, give rise to a supply-demand doom loop, and open the door to stagnation traps induced by pessimistic animal spirits’. In their simple model of the economy, the virus reduces productivity growth and, therefore, causes an initial reduction in employment and aggregate demand. This in turn causes a new reduction in supply since firms’ investment is positively linked to aggregate demand. Firms invest more when they expect to obtain a greater return on investment and such a return is greater when expected demand is larger. The reduction in investment further depresses productivity growth and in turn aggregate demand, and so on and so forth. Thus, the virus gives rise to a perverse ‘supplydemand doom loop’. The loop may be even more troublesome if firms and households are pessimistic about future productivity growth, as such ‘pessimistic animal spirits can push the economy into a stagnation trap’.

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凯恩斯主义对 COVID-19 危机的反垄断反应

一世 。THERISKOFSTANATION COVID-19 病毒对世界经济造成了负面的供应冲击：全球供应链严重中断，工厂关闭，零售店也关闭。为控制传染而采取的社会疏远措施也导致需求严重减少。不幸的是，病毒造成的供应中断可能会持续下去，因为企业可能在一段时间内无法重新开始生产，即使最终获准这样做，他们也可能无法迅速恢复生产。工人不会一下子全部回来，社会疏远措施可能会扰乱生产线，全球供应链可能不得不重新配置，总的来说，生产和分销的成本肯定会上升。此外，一些公司将被迫破产，其资产在一段时间内可能无法有效回收。正如 Fornaro 和 Wolf 所解释的那样，如果没有积极的货币和财政政策干预，供应的持续中断可能会“导致需求驱动的衰退，引发供需末日循环，并为悲观动物引发的停滞陷阱打开大门”精神'。在他们的简单经济模型中，病毒降低了生产率增长，因此导致就业和总需求的初步减少。由于企业的投资与总需求呈正相关，这反过来又会导致新的供给减少。当公司期望获得更大的投资回报时，他们会投资更多，而当预期需求较大时，这种回报也会更大。投资的减少进一步抑制了生产率增长，进而抑制了总需求，等等。因此，该病毒引发了反常的“供需末日循环”。如果企业和家庭对未来的生产力增长持悲观态度，那么循环可能会更加麻烦，因为“悲观的动物精神可能会将经济推入停滞陷阱”。