The principle is not: Whoever wants to be a nation is a nation. It is just the opposite: A nation simply is, whether the individuals of which it is composed want to belong to the nation or not. A nation is not based on self-determination but on pre-determination.
—Friedrich Meinicke 
A nation is [...] a large-scale solidarity, constituted by the feeling of the sacrifices that one has made in the past and of those that one is prepared to make in the future. It presupposes a past; it is summarised, however, in the present by a tangible fact, namely, consent, the clearly expressed desire to continue a common life.
—Ernest Renan 
A nation is a historically constituted, stable community of people, formed on the basis of a common language, territory, economic life, and psychological make-up manifested in a common culture.
—Joseph Stalin 
The difficulties that Marxists (and others) have had in coming up with a definition of ‘the nation’ are well known. What I am suggesting here is that this is not surprising, and that it is not necessarily a problem: indeed, I suggest that those who want and try to produce a definition of ‘the nation’ do so because they understand neither for what nor at what they are looking. In essence, what I suggest is that ‘the nation’ has not been satisfactorily defined by materialists, nor will it be, simply because, as it does not exist, a definition is impossible. Please note that I am not saying that nationalism does not exist, nor that states, even national states or nation-states, nor the ‘national question’, do not exist; simply that ‘the nation’ does not exist. Nor do I intend to say much about the myriad matters of political strategy and tactics that the national question poses. But I contend that a materialist political outlook that is dependent upon a prior definition of what a nation is will always in the end fail.
The definition of the nation, as supplied by nationalist theoreticians, which is nearly always ‘their’ nation (rather than nations in general: nationalism is always particular), is something founded on a conception that what is fundamental is the sharing, by a ‘people’, of a common history, and a common destiny. How is this ‘people’ defined? By the sharing of the common history and destiny. How is the history and destiny defined? By being shared by the ‘people’. (Naturally, practical considerations come into play, especially when it comes to administrative matters, and rules are developed conferring membership of the chosen on those who inhabit a certain defined territory, or who share a certain language or languages, or who fulfil obligations of ancestry. But the root of the idea is the same.) Nationalist theorisation of this type is always particular rather than general. ‘Peoples’ and ‘nations’ are not viewed with equanimity; the fate of ‘other’ nations is unimportant except insofar as they may impact on one’s own. It is one’s own concrete nation that matters; what is fundamental is the view that one’s own (national) people is especially valuable (frequently because it has been chosen by God, or because it embodies some superior values or qualities, or both) and needs to be protected and defended against those not chosen or not displaying the same superior qualities.
Of course, it should broach little argument that this reasoning is false. It is founded on a tautology, and we can accept neither the premise of Divine choice nor the idea of inherent superiorities. We simply can not, and do not, accept this kind of nationalist discourse.
Yet people are nationalists; people accept this reasoning, desire to be a part of one nation or another, and have frequently been moved to undergo the most terrible suffering or inflict the most terrible suffering on others in order to realise this desire. Does this not signify that at some level nations do exist? I argue no; and I argue that neither the existence of religion nor the existence of racist ideologies suppose the existence of God or the existence of races. Belief in something that is not real does not make the thing itself real, as a child would believe that simply because it cannot see it therefore cannot be seen. My argument is not with the existence of ideologies, with nationalism, but with the existence of ‘the nation’.
But there are nations, I hear you say: with governments and flags; national anthems and football teams. Yes, indeed: there are governments, flags, national anthems and football teams. My argument is not with the existence of the national state, but with the nation as a theoretical concept as I have defined it above. But these national states—Germany, the United Kingdom, China, Kenya, etc.—do not appear as ‘nations’: they do not embody the common history and destiny that are required, and, while the majority of the people who live there will accept to some degree the nationalist ideology that is in normal times expected of them not only is this nationalist ideology of recent or very recent vintage but that these people are also prey to other and shifting forms of self-identification other than their shared nationality: class, race, gender, other national ideologies, etc.
What is specific to the modern nation state (as opposed to ‘the nation’)? How does the modern national state differ from the forms of social organisation that preceded it, and from those that will come after?
The modern nation state is founded upon an ideological identification between state and people. The state, the concrete administrative structures of rule and government, derives its legitimacy from the metaphysical concept of ‘the people’, and expresses the unity of the two in terms of ideological constructions such as sovereignty, citizenship, and so forth.
Second, the modern nation state demands an identity between the state, as legitimised above, and territory. Its sovereignty is conceived of as ‘fully, flatly and evenly operative over each square centimetre of a legally demarcated territory.’  Nation states, necessarily, have borders.
From this, the third feature of the modern national state: it is finite, based on an opposition between itself and all the other national states. These identities between the state on the one hand and people and territory on the other implies a final and important distinctive feature: its limited—finite—nature, and, following, the opposition between each actual nation state and all the others: ‘No nation imagines itself coterminous with mankind. The most messianic nationalists do not dream of a day when all the members of the human race will join their nation in the way that it was possible, in certain epochs, for, say, Christians to dream of a wholly Christian planet.’  Nation states may seek to colonise other nation states and subjugate their populations, but they do not in general seek to convert them.
Thus, in the modern nation state, both state and people, and state and territory, are contiguous, and obtain over a defined (and therefore limited) territory. The complex ideological content of these relationships is expressed in sovereignty, citizenship and popular identification with the nation state, and takes the form of national (or nationalist) self-identification of persons or peoples, and is, in normal times, the predominant form of public human self-identification in the modern world.
The modern nation state thus betrays its concrete reality. Yet its ideological foundations reveal a metaphysical nationalist tautology: for if it is the people that legitimises the state then it is the state that demarcates the people.
But the two elements do not appear simultaneously in history: ‘Historically, the formation of states with a centralised government administering and controlling a clearly defined geographical territory preceded the articulation of ideas of the nation.’  The point is central. The pattern is not, as our nationalist friend would have it, that it was ‘the people’ (constituted as the ‘nation’) that made the state, but rather that it was the state that made the nation: the people becomes nationally conscious—becomes nationalist—not when, or if, it shares a common territory (defined by whom?), language, or history, but when it interprets these things, in the terms demanded by our nationalist friend, and identifies them with either an existing nation state or, historically later, desires to establish a national state on the same lines as the already existing other ones. It is the rise of the centralised absolutist monarchies in western and central Europe that makes this process possible: the incipient fragmentation of the medieval social structure cleared the way for the possibility for subjects (and ultimately citizens) to identify with those states that were now beginning to operate over a ‘national’ territory. But it was the state, not the ‘nation’, that came first. As Victor Kiernan argued, in reality, ‘no dynasty set out to build a nation state; each aimed at unlimited expansion. [...] The nation was the empire manqué’ 
In conclusion, then. The ‘nation’, that mysterious entity that eluded the attempts of all the classical Marxists bar Stalin to pin it down, is a fiction, based on a nationalist tautology, and has about as much tangible reality to it as the famous crock of gold said to lie at the end of the rainbow. A definition of it, a materialist, workable and accurate definition that is, is consequently impossible. Nationalism, on the other hand, the ideology that expresses the desire to be a part of a specific (imagined) nation, or to seek representation and recognition for a specific (imagined) nation, is as real as and (at least) as important as, say, Christianity or Islam. National states—the bourgeois national state—as concrete entities are, as we know from our day to day thinking about the places where we live, readily both definable and defined. And the national question is as fundamental a question as it always has been. But ‘the nation’? No.
But does all this matter? I suggest that it does, precisely because of the fact that a failure to appreciate the mythical character of the nation—to accept nationalist ideology, at least in part, as good coin—leads to an inability to appreciate the real character of real national states and real national consciousness. The very acceptance of the existence of nations in the nationalist sense indicates a faulty radar. To accept that nations exist is to accept the nationalist discourse, not only on the part of oppressed nationalisms but also on the part of oppressor nationalisms. In the former case, the danger is an adaptation to nationalist ideology; in the latter, either of adaptation to oppressor nationalism, or of the adoption of a ‘national nihilism’, a refusal to accept the significance or even existence of oppressor, imperialistic nationalist ideology.
I will give two examples of these phenomena, both related to Spain.
Spain is not a nation and the Spanish state is not a national state. A territory comprising all the peoples living within the frontiers imposed on them historically by the Spanish state is not a nation. [...] The project of building a Spanish state has failed since some of the peoples who live within that state have asserted their national identity and have begun to struggle for their rights. 
This is all wrong. The Spanish state is indeed not a nation, not because it has betrayed the promises of Spanish nationalism, but because the idea of the Spanish nation, like that of all nations, is a fiction. But this does not mean that Spain is not a national state: it most certainly and very clearly is a national state, with a national government standing over citizen-subjects, the bulk of whom share, in good part, a reactionary Spanish national consciousness; even if, like many other national states, Spain also contains people who share other national ideologies. And the consequent assertion that the project of building a Spanish national state has ‘failed’ completely underestimates the nature and importance of Spanish national ideology, distorting out of all shape the real nature of the task of building a revolutionary party in the Spanish state.
While this blindness to the falsity of nationalist theory leads here to a near denial of ‘national’ reality, it can also lead to a nationalist adaptation in terms of how revolutionary strategy is mapped out for the oppressed nationalities. José María Iriarte, for example, a Basque militant and Fourth Internationalist, advanced the following vision of the future development of ‘nations’ following the removal of capitalism:
We cannot forecast the future of nations, nor what will be the universal society foreseen by the founders of Marxism. [...] What counts today is the desire to finish with all types of oppression or forced independence; to develop nations in line with the desires of their inhabitants, and ensure that this development is democratic, internationalist and based on solidarity.
The development of nations in an internationalist way? This is pure verbiage, devoid of meaning: the result of a significant concession to the ideology of nationalism, even if an oppressed nationalism, founded on a blindness as to the nature of ‘the nation’.
So an acceptance of the falsity of the nationalist discourse with respect to the nation is not a hair-splitting exercise: viewing concrete national states and concrete nationalities (groups of people sharing a common national consciousness) through the lens of the nationalists’ mystificatory and mystifying concept of the nation has highly important, practical consequences. If, as many feel, the national question is one of Marxism’s great failures, the lack of theoretical clarity in this vein on the part of many Marxists may indeed have played a big part in this.
 Quoted by Robert Berdhal, ‘New Thoughts on German Nationalism’, American Historical Review 77 (1972), 66.
 Ernest Renan, ‘What is a Nation?’, in Geoff Eley, and Ronald Grigor Suny (eds.), Becoming National: A Reader (New York and Oxford, 1996), 53.
 J. V. Stalin, ‘Marxism and the National Question’, Works vol. 2 (Moscow, 1954), 307.
 Benedict Anderson, Imagined Communities (London, 1991) 19.
 Ibid., 7.
 Mary Fulbrook, ‘Introduction: States, Nations and the Development of Europe’, in: Mary Fulbrook (ed.), National Histories and European History (London, 1993), 3.
 V. G. Kiernan, ‘State and Nation in Western Europe’, Past and Present 31 (July 1965), 35.
 ‘Theses on the National Question’ [A document adopted in 1989 by the LCR/LKI, Spanish state section of the Fourth international], International Marxist Review 5.1 (Summer 1990), 113.
 José María Iriarte (Bikila), Do the Workers Have a Country? (Notebooks for Study and Research, 1992), 16.