The eurozone, as designed, has failed. It was based on a set of principles that have proved unworkable at the first contact with a financial and fiscal crisis. It has only two options: to go forwards towards a closer union or backwards towards at least partial dissolution. This is what is at stake.

The eurozone was supposed to be an updated version of the classical gold standard. Countries in external deficit receive private financing from abroad. If such financing dries up, economic activity shrinks. Unemployment then drives down wages and prices, causing an “internal devaluation”. In the long run, this should deliver financeable balances in the external payments and fiscal accounts, though only after many years of pain. In the eurozone, however, much of this borrowing flows via banks. When the crisis comes, liquidity-starved banking sectors start to collapse. Credit-constrained governments can do little, or nothing, to prevent that from happening. This, then, is a gold standard on financial sector steroids.

The role of banks is central. Almost all of the money in a contemporary economy consists of the liabilities of financial institutions. In the eurozone, for example, currency in circulation is just 9 per cent of broad money (M3). If this is a true currency union, a deposit in any eurozone bank must be the equivalent of a deposit in any other bank. But what happens if the banks in a given country are on the verge of collapse? The answer is that this presumption of equal value no longer holds. A euro in a Greek bank is today no longer the same as a euro in a German bank. In this situation, there is not only the risk of a run on a bank but also the risk of a run on a national banking system. This is, of course, what the federal government has prevented in the US.