The causes of this shambles are incredibly simple:
A) Politicians are in general feckless scum. They are presumably (mostly) fairly intelligent, so they should KNOW that you can’t forever borrow more than you can be SURE to be able to repay. In the old days this was known as “living within your means”, but this is a concept very much out of fashion, especially since Brown was given the keys to our money.
DESPITE THIS, to curry favour with their troops and ensure their reelection and thus access to the goodies that go with it, they CONSTANTLY overborrow and pretend it doesn’t matter. There is also an element of cowardice here, since they cannot bring themselves to say: “No, we can’t afford that.” Of course, as far as the PIIGS are concerned, they couldn’t EVEN bring themselves to say: “No, GERMANY can’t afford that.”
This over-borrowing cannot go on for ever, but in the Brown-Zapatero-Burlesqueonly era (not to be confused with the Dinosaur era, even if it felt a bit like it) the feckless, self-deluded and lying scum masquerading as “leaders” went totally OTT, thus leaving their countries in massive debt.
B) Many of the plebs (though not including those who said this would all end in tears and for their pains were often labelled by the unintelligentsia as “idiots”), connived in this delusional bingeing and gobbled up in their greed whatever apparent German-financed freebies that were on offer, such as retiring at 45, passing on your pensions to relatives when you died, having a so-called job for life, working 3 hours a day and so on (see Greece).
C) ERGO, as follows from the above, this crisis is NOT the fault of the following usual and convenient scapegoats, who have NOTHING TO DO WITH IT:
the ratings agencies
not borrowing enough (this is Hollande’s current suspect, which I think you have to admit is quite funny in the circumstances – his remedy is like giving a drunk a full whiskey bottle.)