I found a very elegant answer in Mises' Lecture Transcriptions from 1951, without requiring the opposing side of knowing much economics economics--it's the ignorance of the opposing side that always makes such debates tedious:
“Why can’t credit be expanded on an international basis? The failure of credit expansion is due not to the fact that it has been done on a national basis only, but to the fact that it is impossible to substitute paper for non-existing capital goods. It was not realized that what is needed for an economic expansion is more capital goods, more previous savings… The real reason why such an international bank cannot succeed is the impossibility of answering this question: ‘Who should profit from this credit expansion in the short run?” Suppose there was one central bank… Such an international bank could increase the amount of credit available either by printing additional banknotes or by giving additional bank credits by checkbook money… [T]he whole additional amount is loaned to one country. This country[’s]….people will have more money… [they] will bid up the prices of things they want to buy… they will be in the favorable position of being able to buy from other countries not yet adjusted to credit expansion.This first country will be the winner, and the others will be the losers. The other countries will still sell at old [lower] prices but they will have to buy at new higher prices… ‘Who will get loans?’ … Every group of countries will propose a system of distribution. The Far East will favor distribution according to population. The advanced countries, for instance, will suggest distribution according to the total amount of yearly production or according to national income. Therefore, such plans are more or less useless. The only value of the IMF, which has been one of the most conspicuous failures of world policies of the last twenty years, is that it occupies office space in Washington” (Mises [1951] 2004:74).
Mises, Ludwig von. [1951] 2004. Business Cycle and Beyond. Lecture Transcriptions, June 25 1951—July 6 1951: Free Market and Its Enemies. Irvington-on-Hudson: Foundation for Economic Education.