In practice, expanding national debt requires eurozone-wide unanimity. Ask Greece.
> expanding national debt
I feel the need to point out that currency debasement is a fundamentally different thing from taking out loans/issuing bonds/other debt. If anything, currency debasement reduces national debt in real terms, by devaluing the currency it's denominated in. I'm not especially clear on the situation, but I was under the impression that Greece's problem was that noone was willing to lend them money due to a expectation that they wouldn't be paying it back, not that they were prohibited from borrowing by EU law, but even that would be a different thing from being prohibited from printing money.
If anything you have to lend more money to Greece and only give the most productive companies/sections of the government access to loans, if Greece's GDP was 355 billion € in the past it can recover up to that old level.
Debasement of gold happens because gold isn't printed. You need to dilute it in order to make more coins. In a gold currency system, it's the gold that's the "real" currency. Gold value rises and falls, but that's not debasement. The coins are debase. It's theoretically possible for a gold coin to be debased, but also worth more because the value of gold has increased by more than the coin has been diluted.
Euros and dollars aren't redeemable for anything, so debasement doesn't really mean anything.
In the Eurozone, when a national government runs a deficit (all of us, currently) then the ECB issues a loan. That money is then available for the government to spend. This is where Euros come from.
The ECB refused to loan/print money to the Greek government until they agreed to certain demands. Ireland, my country, did agree to the demands and the ECB made some euros for us to pay our banks with.
It works in a similar way in the US. The Federal Reserve Bank gives their government dollars, and they US government give them bonds in exchange... a loan. The Fed can then sell those bonds to anyone who wants them, or hold them.
The one unbreakable eurozone rule is no printing your own money. The "Greek Crisis" was a fear the Greece would try to issue its own bonds, which would trade at a different rate & effectively create their own separate euro... confusing everyone.
Yes, there is the straight-jacketted neoliberal constitution that makes everything terrible, but that's separate. I really hope they can fix that.
The real important thing here is establishing the importance in preventing the race-to-the-bottom, so more important things like multinational carbon taxes, developing country capital controls, etc. are newly inside the Overton Window.