PsB
Citizen of Nowhere™
Self Determination of "nations", "peoples" and ethnic groups is one of those wonderful principles that one cannot but agree with, in theory. It was sort of applied after WWI with disastrous results, but then results might have been equally disastrous if other frontiers had been drawn.
But where does one draw the line? The Basques, Sardinia, the South Tyrol/Alto Adige, Wales, Catalonia?
I'm reminded of "Passport to Pimlico," or to take the principle to its logical extreme, that I and my family living on a farm in Yorkshire could declare ourselves independent from the UK. There is, actually, a town somewhere in northern Italy that claims to be a kingdom and coins its own money, although nobody seems to notice much.
First, why would one have to draw a line somewhere? And who does the drawing?
Second, the key concept in self-determination is "self". People should have a voice and ultimately a vote. If they want to leave one particular entity to set up a new one or join another existing one, they should ultimately be able to do so. The alternatives are worse, IMO, at least over the long term.
The process has to be managed in a proper way, over years/decades rather than months, with excellent guarantees for minorities, etc. Difficulties start when the constitution of the country prevents these discussions or votes from taking place, as seems to be the case in Spain at the moment, or when little green men appear from nowhere to create "facts on the ground", as in Crimea or elsewhere.
So if the Basques, Welsh, Catalans, Corsicans, Süd-Tiroler etc. can come up with a solid majority as part of a respectable democratic process, who's to tell them that they can't do that?