Euro rules row bodes ill for Europe's future

With the dust still settling over the bad-tempered rows over the euro rules that have dominated the headlines this week, now is a good moment to consider what the economic and political consequences might be.

But first, it is important to understand why the rules were set up and to what extent they have been discarded this week.

The rules that govern the euro - known as the Stability and Growth Pact (SGP) - were established in 1997 mainly at the request of Germany.

The id...