A core principle was constraints on capital. Governments were permitted to control capital flight, a principle that still is in the IMF rules, though ignored. And currencies were regulated within a narrow band. The motives were twofold. The first was economic: Keynes and White believed that these measures would stimulate economic growth and trade. The second was sociopolitical: both understood that unless governments are able to regulate capital, they will not be able to carry out social democratic (welfare state) measures. These had enormous support among populations that had been radicalized by the Great Depression and the anti-fascist war (World War II).
The basis for the sociopolitical motive is straightforward. Free capital movement establishes what international economists have called a “virtual parliament” of investors and lenders, who carry out a “moment-by-moment referendum” on government policies. The “virtual parliaments” can “vote” against these policies if it considers them irrational: enacted for the benefit of people, rather than profit for concentrated private power. They can “vote” by capital flight, attacks on currencies, and other devices offered by financial liberalization. Keynes considered the most important achievement of Bretton Woods to be establishment of the right of governments to restrict capital movement.