Before starting this post, let me highly recommend George Selgin's recent post on NGDP targeting. Nick Rowe has a post discussing a scenario where a lack of media of exchange disrupts trade, without affecting employment and output: I would call that a "recession", even though (by assumption) output, employment, and (aggregate) consumption are unchanged. People are worse off, because of a reduction in the volume of exchange, due to a reduction in the circular flow of money around the Wicksellian...