In a correctly specified economic model, the number of equations equals the number of unknowns, and the model tells you what will happen. If you think that the model is telling you something bad will happen, and you want something better to happen, you have to remove (at least) one of the equations, and replace it with a different equation, so that the model now tells you that something different will happen. And you try out different equations until the model tells you something will happen that you like a lot better than what the model originally told you will happen.
Then you say that the original equation ought to be replaced by the new equation. That's your advice.
Which is a bit strange, when you put it like that.
You can't just replace any of the equations with anything you feel like replacing it with. Well, you can, but nobody would take your advice very seriously if it consisted of saying "If we doubled productivity we would be better off". They might believe you, but if there's no way to double productivity your advice would be useless.
Normally we get around this problem by only messing with the equations that describe government policy. If the government asks for your advice on what it should do, or if you at least think that there is some small chance it or a future government might listen to your unsolicited advice, and roughly shares your beliefs about what is a good or bad thing to happen, then it makes sense to mess around with the equation that describes government policy.
But I just can't get my head around how to apply this normal way of getting around the is/ought problem when it comes to the Eurozone.
The fundamental problem is that it's very hard to get 17 governments to agree on how the European Central Bank should act in its role as lender of last resort. Which sovereigns get helped, and how much? Which countries' banks get helped, and how much? If a bust bank gets nationalised, which sovereign takes it over? Can you nationalise a bust sovereign?
You can't really give economic policy advice in that sort of context. The best you can do is act like a mediator trying to keep a disfunctional 17 person marriage from breaking up.
Why even bother? Even if you could find a magic cure for this crisis, you don't solve the problem. The problem is the marriage itself. The best advice you could give would be to propose some way of breaking up which minimised the costs to all 17. The Eurozone doesn't work. It's going to break up anyway, I think. The only question is when, and whether it's a negotiated break up or a break up from force majeure when sovereigns default, and banks go bust, and countries will have no alternative but to issue their own currency if they want to pay their government workers and pensions and re-open their banks.
I've written a lot of posts about the Eurozone. But they are "is" posts, about what I think will happen. And the things I think will happen are bad things. And I feel some sort of obligation to say at least something about what I think ought to be done to try to prevent some of those bad things happening, or at least make them less bad. This is as near as I can get to an "ought" post about the Eurozone.
Each country ought to restore its own national currency. I think this will happen anyway. But it would be better if they all did it at the same time, rather than one after the other. It will still be very nasty. But the nastiness won't last as long. And what's happening now while we wait for the break-up isn't so great either.