He has written a newspaper column on the unrest in the Ukraine in which he states that the two possibilities are that the current violence will tear the country apart or else help to bring about the creation of a "state nation".
What is a state nation? Professor Garton Ash offers the following definition:
A state-nation is one in which a shared civic national identity is created by the state, rather than a single ethnic national identity being embodied in it.
A state nation would mean the end of a meaningful national tradition for Ukrainians. In reality it is just a new term for a liberal civic nationalism in which a shared commitment to liberal political institutions and values is what is supposed to hold a nation together.
I've written a detailed criticism of civic nationalism before. A civic nationalism is dissolving of a national tradition. First, it means that anyone, anywhere can be a member of the nation, just so long as they uphold liberal values. That not only encourages open borders and uncontrolled migration, it also makes a national identity indistinct - the identity of one civic nation is very close to those of the others.
Another problem with a civic nationalism is that it is not the end point in the unfolding of liberal principles. It is merely a staging post. Once it is achieved the next step for liberals is to complain that there is still discrimination on the basis of citizenship, i.e. that benefits are given by the state to citizens that are not given to non-citizens. In the longer run, the moral focus shifts from civic nationalism to internationalism.