Comment: Lucas on involuntary unemployment
评论卢卡斯对非自愿失业的看法，指出他误解了凯恩斯对自愿、摩擦和非自愿失业的区分，并认为所有失业本质上都是非自愿的。
Keynes distinguishes three concepts: voluntary, frictional and (Keynesian) involuntary unemployment. Frictional unemployment is a Classical form of involuntary unemployment (not voluntary, as Lucas suggests), and reflects the Marshallian, rather than Walrasian, treatment of time and equilibrium. Lucas contradicts both Keynes and Pigou in asserting that there are always immediate vacancies for unskilled labour, and abstracts from the very problem that Keynes seeks to address. If voluntary unemployment is re-defined appropriately, as De Vroey helpfully suggests elsewhere, the prefix 'involuntary' is dispensable, not because all unemployment is voluntary, as Lucas would have it, but because it is all involuntary. Copyright 2006, Oxford University Press.