Having an unique money that rules the entire world is not a dream.
During 300 years, starting from 1500s, Spain controlled the Spanish dollar or piezas de ocho. Between the 18-20th centuries, european countries and others adopted the gold as a stardard currency, but while the gold was the most used, the Sterling Pound was also considered as a global currency.
Today, we have the United States Dollar, which was implemented as standar currency (not legally, the US dollar was introduced as a reserve currency) at Bretton Woods Conference, in 1944. But this was not the first choice in that conference, actually the option UK and their europeans parts wanted to put was the Bancor, a proposal introduced by John Maynard Keynes, which would be a unit of account used to track international flows of assets and liabilities, supervised by a Global Central Bank, today International Monetary Fund. Gold could be exchanged for bancors (the unit of account), but bancors could not be exchanged for gold.
Having a global currency brings us some advantages at the time to make global trade in those days, actually. You don't want to worry all the transactions in different currencies? Using the dollar, that is solved. Problems with some economic policy in certain countries? That is also a problem solved because the dollar doesn't change their monetary policies for no reason and so on.
The disadvantages? Lot of them but the most important part (in the field of economic policy) is the Triffin Dilemma, the conflict of interests between international and local objectives concerning monetary policies.
After the 2008 crisis, the issue about a global currency was on the floor again and with the Zhou Xiaochuan's essay about a global currency, China questioned the role of the dollar as a standard currency. Zhou proposed:
(...) The centralized management of part of the global reserve by a trustworthy international institution with a reasonable return to encourage participation will be more effective in deterring speculation and stabilizing financial markets. The participating countries can also save some reserve for domestic development and economic growth. With its universal membership, its unique mandate of maintaining monetary and financial stability, and as an international “supervisor” on the macroeconomic policies of its member countries, the IMF...
If the text above sounds familiar, the idea of Mr. Zhou was taken from the Bancor's proposal of 1944. But with these propositions, there are two main questions:
- As a country, are you prepared to deliver your economic sovereign to an international supervisor?
- Do you trust -as a country- in the IMF (or any other organization/supervisor) and their economic policies?