Later writers came to recognize that there are other essential criteria for a successful currency union, which are difficult to achieve without deep political integration. Peter Kenen argued in the late 1960’s that without exchange-rate movements as a shock absorber, a currency union requires fiscal transfers as a way to share risk.
后来的研究者开始认识到成功的货币联盟还需要其他关键要素，而这些要素在没有深度政治一体化的情况下很难实现。柯南（Peter Kenen）在20世纪60年代末指出，如果没有汇率变动作为冲击吸收器，货币联盟就需要财政转移来作为分担风险的办法。