ON SEPTEMBER 18th Scots will vote on whether they want to remain, alongside residents of England, Wales and Northern Ireland, part of the United Kingdom. Many do. Polls tend to place support for the "Better Together" camp (putting the case for the union) at roughly 40%. Some 30% of Scots declare themselves undecided. So far, the pro-independence camp has struggled to secure support of much more than 30%. Yet that is itself striking. Since 1997 extensive powers have been devolved from London to Edinburgh. English taxpayers' money has travelled in the same direction—Scotland receives a disproportionately generous grant from the central state. Scots are well represented in the political, intellectual and cultural life of the wider country. Yet over the same period, according to the National Centre for Social Research, support for independence has remained relatively consistent. Why? The history of the upcoming referendum provides an explanation. In 1997 the then-Labour government offered Scots a vote on the creation of a devolved Scottish Parliament. The thinking was that giving it control over matters like education, social services and home affairs would sate Scots' appetite for independence (stoked by 18 years of a Conservative government that few Scots had voted for). They duly voted yes, but the devolution that ensued had the opposite effect: according to Ipsos MORI, a pollster, as Scots gained their new institutions, national feeling grew. Young adults who grew up during and after this period are even referred to as the "Braveheart generation" for their proud Scottishness. This trend contributed to the election in 2011 of the first majority pro-independence Scottish government, led by the Scottish National Party (SNP), which promptly announced its plans for the referendum.

Scottish voters are more left-leaning than the British population as a whole (particularly the English). Devolution has therefore led to divergence: north of the border, public sector reform is less developed than in England. The welfare state is more generous, too: things that English voters must pay for, such as university tuition and medical prescriptions, are still free in Scotland. Three years of centre-right administration in Westminster have only accentuated the differences. The English public sector has endured deep cuts; the Scottish one, by contrast, is relatively unscathed. So Scots might be forgiven for thinking that more autonomy means more goodies. The SNP has certainly implied that much in the independence campaign so far. All this talk of the social-democratic good life points to a third factor: the debate about Scotland's place in the world. The SNP likes to compare an independent Scotland to successful countries like Denmark, Norway and Sweden; proof, it claims, that small, northern European states can thrive in a globalised world. (Ireland and Iceland were swiftly struck from the list when their economies collapsed in the financial crisis.) That message—ditch England, with its nuclear weapons and anti-EU politics, and embrace peaceful, internationalist Nordic-ness—appeals to many Scots, particularly younger ones.

For some, then, the symbolic, economic and geopolitical vision of the pro-independence camp is grounds enough to support a split from the union. The challenge for the "Better Together" camp is to persuade some of them (and undecided voters) that it is possible within the union. That amounts to promises of further devolution, further social democratic goodies, and further autonomy over international matters. All of which means that even if the unionists win the referendum, those who want Scotland to leave may get what they want anyway.