Residents of Scotland will head to the polls on September 18 to vote on whether to preserve or dissolve their 300-year old union with the United Kingdom. It is a stunning example of the persistence of nationalism despite decades of assurances by liberals and socialists alike that globalization dissolves national identities and/or makes national sovereignty increasingly irrelevant.

In a global context, the Scottish independence movement is unusual because Great Britain has been unified for so long, and the union (in 1707) was voluntary and not a result of conquest. Also, there has been no repression of Scots by the English for centuries, nor any threat to their ethnic identity; and the UK is a well-functioning democracy with robust human rights and a high standard of living.

Elsewhere in the world, Matt Qvortup reports, there have been 49 independence referenda since Texas voted to secede in 1861, and most of them have been ended in secession, with an average Yes vote of 83%. In Britain there have been ten referendums since the vote on whether to stay in the European Economic Community in 1974, and in seven of those cases voters opted for change over the status quo. So to the extent that this broader pool of cases is relevant, the chances of a nationalist victory cannot be ruled out.

As election day approaches, Scottish voters realize that they are facing a momentous decision and the country is in a grip of intense and for some exhilarating debate. For a flavor of the issues, check out the pro-independence website Yes Scotland and its pro-union rival Better Together. For a neutral academic discussion site, see Future of UK and Scotland. For the pro-independence case, see the speech by Alex Salmond, First Minister of Scotland on March 4, 2014, or read this article by Neal Ascherson. A trenchant argument for preserving the union is made by Gideon Rachman in The National Interest. Various celebrities have weighed in, with pro-independence Sean Connery facing off against Edinburgh resident J.K. Rowling, who donated £1 million to the No campaign.

South of the border, the independence movement is often seem as something whimsical and irrational, the product of a nostalgia for a land of wild, free, poetic Highland past. In a concise summary of the debate, John Lloyd suggests that Scotland is torn between “heart and head,” between a headstrong assertion of “who we are” and a rational calculation of collective self-interest.

Alternatively, the nationalist movement is portrayed as the creation of self-interested politicians – notably, Alex Salmond, the leader of the Scottish Nationalist Party – seeking power and a place in the history books. In this reading, independence is almost the accidental result of a sequence of short-sighted decisions by Labour politicians in Westminster – a failed devolution referendum in 1979, the creation of a Scottish parliament in 1998 – who had no inkling that their actions could lead to the break-up of the UK. (Just as Mikhail Gorbachev did not realize that glasnost and perestroika would lead to the collapse of the USSR.)

In her study of the break-up of Yugoslavia, Secessionist Movements and Ethnic Conflict, Beata Huszka argues that secessionist movements deploy one or more of three frames: ethnic security, democracy, and prosperity. Scots do not invoke any threat to their ethnic identity, so the case for independence depends on the latter two appeals – democracy and prosperity.

The democracy case hinges on the fact that Scots are more left-leaning than the English. Scots complain that they are repeatedly ruled by Conservative governments which would not have won power in an independent Scotland. The Conservative Party currently holds only 15 out of 129 seats in the Scottish Parliament. In the 2010 British general election, they won 17 percent of the votes in Scotland, and they hold just one of the 59 Scottish seats in the Westminster parliament (which is elected on the first-past-the-post electoral system, unlike the Scottish and European parliaments, which use proportional representation). After the 1997 Labour landslide the Conservatives did not have a single MP in Scotland.

More broadly, in a climate of increasing disillusion with the institutions of democracy (from banker bailouts, to phone backing, to MP expenses fraud) independence is seen as vote for social change and the reinvigoration of participatory democracy. For example, Hilary Wainwright argues that the referendum is “not even about nationalism” but rather is “an invitation to say no to a super power whose wars, most recently against Iraq, the Scottish people found abhorrent, and yet have been forced to join; a chance to say no to decades of social injustice and sacrifice at the altar of the global market by Conservative and Labour Governments at Westminster.”

Scotland already enjoys a high degree of devolution of powers. It has its own legal, police and education systems, complete control over its National Health Service, and so on. It lacks autonomy in foreign and military policy – an important point given that Britain’s controversial Trident nuclear deterrence submarines are based in Faslane, Scotland. It also lacks control over fiscal and monetary policy – a sensitive issue given the UK coalition government’s commitment to austerity to forestall inflation and preserve the value of the pound.

The counter arguments to the democracy thesis are:

(a) any democracy is about winning some and losing some – and Labour governments have ruled Britain for half the post-war period.

(b) If you believe in social democracy and social justice, then these goals are more likely to be realized in the 60 million strong British community if Scotland stays part of the union. Thus the utilitarian principle of “the greatest good for the greatest number” argues for the preservation of the union. The Scots should make common cause against the London elite with their cousins in the struggling north of England.

Sometimes it is argued that Scottish secession would mean permanent right-wing governments in the rump UK. This is an exaggeration. Because Scotland has only 4.2 million voters out of a UK electorate of 46 million, it is quite rare for Scottish votes to swing an election (to Labour, from the Tories). It only happened twice since 1945 (in 1964 and 1974, and only for a total of 26 months). Additionally, in 2010 Scottish votes did deny the Conservatives a majority at Westminster, and forced them to form a coalition with the Lib-Dems.

(c) One issue is who gets to vote. The decision was made to restrict the franchise to people residing in Scotland. That gives the right to vote to 400,000 people living in Scotland who were not born there, but disenfranchises 800,000 Scots living elsewhere in the UK. (In contrast, in recent referenda in Montenegro and South Sudan emigres were given the right to vote.) The SNP promoted this approach presumably out of fear that diaspora Scots would be more likely to vote No.

Another contentious decision was to lower the voting age to 16 – Austria is the only other European country with such a low voting age. The SNP was gambling that younger, more impressionable voters would be easier to rally to their cause.

(d) There is also the classic liberal argument against secession (as laid out for example by Michael Ignatieff): that it divides people who were peacefully living together, forcing them to pick one identity at the expense of other identities and creating a downward spiral of action and response.

On the prosperity front, oil is central to the psychology of the nationalists. It was the discovery of oil in the North Sea that enabled the hitherto marginal Scottish Nationalist Party to capture 30% of the vote in 1974 with the slogan “It’s Scotland’s oil.” Oil and gas revenue remains key to the economic viability of an independent Scotland, and hence to the political confidence of the nationalist movement. The problem is that oil only accounts for 15% of Scotland’s trade, and other sectors of the economy would be hard hit by the uncertainty following independence. Leading banks have signaled that they would probably have to re-register in London, where most of their business originates, to conform to EU rules.

The main counter-arguments of the No campaign have focused on the pound sterling, Scotland’s status within the European Union, and the question of budget subsidies.

Alex Salmond has tried to argue that “it is Scotland’s pound too” and that an independent Scotland has the right to continue using the pound as its national currency. This is a somewhat unusual stance for a nationalist – historically, having your own currency was up there along with the flag and anthem as symbols of national autonomy. English politicians responded by insisting that London would not allow Scotland to print money to cover government deficits – citing the crisis in the Eurozone as a sobering example of what happens when monetary union runs ahead of fiscal union.

In the televised debate on August 5 between Salmond and former Labour Chancellor of the Exchequer Alistair Darling, head of the Better Together campaign, the latter hammered home the currency theme, arguing that “even an eight year old can name a country’s capital, flag and currency” but Salmond is unable to commit an independent Scotland to using the pound sterling, the Euro, or a new Scottish pound.

Salmond’s clinging to the pound sterling is an example of his broader political dilemma. To secure more than 50% of the votes on September 18 he needs to win over wavering voters who are worried about the possible disruptive impact of independence and who do not share the fervor of the nationalist true believers. Hence his insistence that Scotland will retain the Queen as head of state and the pound as its currency, and will stay part of the EU and NATO. Speaking on the BBC on August 7, Scottish Conservative Ruth Davidson characterized his position as one where “everything will change but nothing will change.”

On the European Union, the question is whether Scotland would automatically stay a member, or would have to apply for entry as a new applicant. The EU charter is ambiguous on the issue, but given the opposition of some EU members (notably Spain) to secession it is unlikely that Scotland would get a smooth passage to membership.

The budget subsidy issue arises because Westminster spends £1400 per head (15%) more on Scots than on residents of England (in part, this is seen as informal compensation for North Sea oil revenues). Thus for example Scottish students go to university for free, but English students have to pay £9,000 annual tuition (through state-provided loans). NHS patients in Scotland have free prescriptions while in England they pay £8 per item.

No survey over the past year has showed a majority favoring independence. The latest polls put the Yes vote at 46% and No at 51%, with forecasters confidently predicting a No victory. However, given the vagaries of turnout, and the uniqueness of the occasion, it is impossible to rule out a victory for the Yes campaign. And even if the referendum fails, a narrow margin of victory for union would mean that the issue would not go away. More devolution of policy responsibility is bound to follow – with likely pushback from English counties, triggering more calls for independence from north of the border.