Between 1870 and 1914, there was a global fixed exchange rate. Currencies were linked to gold, meaning that the value of a local currency was fixed at a set exchange rate to gold ounces. This was known as the gold standard. This allowed for unrestricted capital mobility as well as global stability in currencies and trade; however, with the start of World War I, the gold standard was abandoned.
At the end of World War II, the conference at Bretton Woods, an effort to generate global economic stability and increase global trade, established the basic rules and regulations governing international exchange. As such, an international monetary system, embodied in the International Monetary Fund (IMF), was established to promote foreign trade and to maintain the monetary stability of countries and therefore that of the global economy.
It was agreed that currencies would once again be fixed, or pegged, but this time to the U.S. dollar, which in turn was pegged to gold at US$35 per ounce. What this meant was that the value of a currency was directly linked with the value of the U.S. dollar. So, if you needed to buy Japanese yen, the value of the yen would be expressed in U.S. dollars, whose value in turn was determined in the value of gold. If a country needed to readjust the value of its currency, it could approach the IMF to adjust the pegged value of its currency. The peg was maintained until 1971, when the U.S. dollar could no longer hold the value of the pegged rate of US$35 per ounce of gold.
From this point in, governments used fiat currency as the basis of the monetary system. This system had two defining characteristics: (a) non-convertibility; and (b) flexible exchange rates. You need to recognise this major shift in history before you can understand why the economic policy ideas that prevailed in the previous monetary systems (based on convertibility) are no longer applicable. You cannot assume that the logic that applied in the fixed exchange rate-convertibility days translates over into the fiat currency era. The fact is that it doesn’t.