What is the impossible trinity? The Mundell-Fleming trilemma - The Economist explains economics

This week “The Economist explains” is given over to economics. Today’s is the last in a series of six explainers on a seminal idea.

IN THE run-up to the launch of the euro, in 1999, aspiring members pegged their currencies to the German mark. As a consequence they were obliged to shadow the Bundesbank’s monetary policy.