Which people, which group, do you belong to? How do we know who is Them, and who is Us? Where do your political loyalties lie? In a way these are simple questions. There are many contexts in our daily lives when we could answer them well enough. We speak common languages with people around us (and often with the same accent). Many of us live in neighbourhoods and recognise ‘neighbours’ as a distinctive group to which we belong. If we pray regularly in a mosque or church then we might identify ourselves with others as part of a ‘community’ there; if we drink regularly in the local pub or cafe we might feel the same. There can be many, overlapping communities, large and small, and we can belong to a range of them.

What about your primary political loyalty? Many people will happily see themselves and others as fellow British or French or Brazilians or South Africans, whatever other factors may separate them from some of their compatriots. This sense of belonging will generally transfer to accepting the French, Brazilian, etc., government as legitimate, however much one wants to see the policies or the composition of the current government change.

It is easy to say ‘many people’ will be able to identify, and feel comfortable with, their larger political loyalties or belongings (and it’s an old trick of political theorists to invoke the ‘many people would …’ defence for what they are arguing). Equally, many will not. People can be ‘caught’ without or between primary political attachments. On the one hand, many societies today are multicultural or multinational, their citizens having diverse, multiple and shifting loyalties. On the other hand, massive movements of people on a global scale have been evident in recent years, for example the movement of Afghanis and Iraqis to Europe and elsewhere in the 1990s and early 2000s in the face of war, oppression and poverty. Such massive movements of people make the experience of indeterminate loyalties and belongings – indeed, statelessness – a common experience. Further, many minority communities within nation-states commonly feel ambivalent about their compulsory primary loyalties, for example indigenous peoples in the USA, Canada, Australia and New Zealand.

Many residents of places such as Macedonia, Kosovo, the Palestinian territories, Cyprus, so-called ‘Padania’ in northern Italy, Catalonia, the western Sahara, Abkhazia, Aceh, Scotland and Quebec live with constant questioning about what should be their primary political loyalty – their nation, or their country. Some will feel that an alien political identity is being imposed on them by a state they regard as illegitimate: the Israeli state in the Palestinian territories, the Moroccan state in the western Sahara, and the Georgian state in Abkhazia. Their literal neighbours may defend with equal vehemence their loyalty to those same states. Although at one level each case is unique, in many such places there is anguished and bloody conflict over legitimacy, loyalty and belonging. Strong sentiments can be fuelled by nationalist agitation and propaganda. Political struggles over land and identity can take the form of ‘border disputes’ at one extreme to ‘ethnic cleansing’ and ‘civil war’ at the other. The impact these conflicts have on the lives of many thousands of individuals and families are well documented (Huysmans, 2005). Nationalism and national self-determination are living political ideas that people do indeed live (and die) for.

The main reason that such conflicts are so important to leaders and followers caught up in them is that to achieve and sustain statehood for one’s nation is the ultimate expression of political independence, as it has been since the rise of the modern nation-state around the time of the French Revolution. At that time, the nation-state began, for a complex variety of reasons, to see off its great historical rivals – city-states and empires for example. Beginning in Europe and spreading through colonial conquest and domination, the nation-state has become the basic political unit across the globe (Gieben and Lewis, 2005). Although the fact and the value of its primacy is much debated today, especially by strong advocates of ‘globalisation’, it still provides the fundamental frame through which we understand the government of people and territory. There are local government units within countries and supranational governing institutions ‘above’ them (such as the European Commission and the European Parliament in the EU), but the nation-state is the basic, bedrock unit. There have been different theories about what can make political power legitimate. But when utilitarians, contract theorists, Marxists and others argue about political legitimacy they are almost always arguing about the rightful government of nation-states.

Because statehood is a prized possession, it is hardly surprising that fundamental political questions about ‘them’ and ‘us’ can invite strident answers: most Kosovan Albanians for instance are utterly adamant that they are not Serbs and should not be governed as part of Serbia. No case is that straightforward, of course. Up to the 1990s, Kosovans had not sought independence from Serbia, but rather civil rights. The wars in ex-Yugoslavia provided a context for the emergence of nationalism; other demands transformed into demands for national self-determination. In terms of general principles the case of Kosovo does raise the tricky question: where two or more resolute communities claim the same piece of territory as theirs, where each wants to be governed by people from (as they see it) their own group, who can decide what is right? Are there any broadly acceptable criteria to guide us when we ask who has a right to national self-determination in different cases or disputes?

I want to show how political theory has responded to fundamental questions thrown up by nationalism, the assertion of the right to self-determination, and the closely related rise in secessionist movements. As we shall see, there is no consensus. But theoretical debate has given us some refined and intriguing responses.