What reasons do people give in favor or against Scottish independence? To put it very crudely, not having followed the discussion too closely, the Yes argument is mostly nationalistic and the No argument is mostly economic, which is basically to say it's about welfare. Thus, the Yes people are saying that Scots are a nation and therefore they deserve to have their political independence - it is their right to control their own collective affairs. The No people are saying that an independent Scotland will either do worse than it's doing now or terribly bad, with all sorts of catastrophic scenarios flying around. Of course, the Yes people have responded by saying that independence would not have such dire consequences and may even have some economic benefits but their argument is still, for the most part, about national self-determination.
That brings me to one argument in favor of Yes. It seems really important to have on the history books a living example of a nation achieving independence through a vote. It's a chance to have a nation gain statehood by ballots, not bullets. Some political leaders are worried that other national minorities in Europe are looking at this vote and thinking about their own national aspirations. Those leaders are worried that a successful secession would lead to instability but it seems to me that such a peaceful campaign is a remarkable example of the potential of discursive, non-violent means of achieving political goals. That's especially true due to the positive nature of the Yes campaign that, as far as I've seen, avoided vilifying the English to get votes (though it would have been popular among some Scots and they probably have good reasons for it too). Whether or not an independent Scotland would be successful is a separate question that might also impact how other minorities think about their own independence, but whether you think your national minority group should secede or not, I think it's preferable that you think about trying to achieve it through the ballot box.
Which leads to the problem of that Yes argument. That the conversation has been couched mostly in nationalistic terms is a source of concern. For various reasons I can't enumerate here I am very skeptical about the idea of nationalism in general and in particular about nationalism as a basis for political independence. One troubling aspect of nationalism is that the idea that nations should have their own states and states should be nation-states forces people to choose. Why can't someone be both Scottish and British? If nations are to have their own state, each state should have a clear nation. If there's a nation that doesn't have a state - either it should have its own state, or live as a minority in a state that isn't its own.
Ultimately, I think that there is an important component that's missing in this discussion. That is the democratic component: Would a new independent state would improve the Scottish people's ability to affect the matters the concern their own lives? Some Yes people have made that argument, usually within the nationalistic framework: As a nation, the Scots will be in a position to manage their own life. But I'm not interested in the Scots as a nation, but in Scots (and the English, and all other affected parties) as individuals. Would it improve individuals' democratic standings? Will they have more say in decisions that impact their lives?
I'm not sure, and I haven't heard many people make a persuasive argument this way or the other. Some Yes people think that an independent Scotland would result in an improvement in democracy because there is a difference in preferences, generally speaking, between the population of Scotland and the rest of the UK: Scots tend to support more social policies, such as government investment in education and healthcare than the policies of the UK government. Therefore, an independent Scotland would reflect better the preferences of most Scots while the remaining citizens of the UK would have policies that reflect their preferences.
This might be true, I don't know enough about the UK to say much about this. I do think, however, that there are various other issues that may complicate the story. Will an independent government in Scotland be sufficiently strong to even have its own policies in the face of pressures from International markets and a strong neighbor? For example, if the now independent Scotland attempts to regulate labour standards more rigorously will they be able to enforce it given the competition with their Southern neighbors or will they have to end up complying with the standards of the Westminster government only that now it'll be a much more conservative government in which they will have no vote?
Which leads me to the last point about referendums being not terribly democratic. Of course, they are much better than bullets, in terms of their democratic credentials, and definitely better than conquest, annexation and monarchical matrimony. But if you think democracy is about people participating in the government of their own collective lives, you want to create more opportunities for people to govern, not less. The way decisions should be made is continuously over time, not in a one-off moment where an on/off switch is thrown this way or the other. We need to have processes of deliberations where elections take place regularly, allowing people to think and rethink their positions, and also experiment with one kind of policy and later replace it with another.
The problem with this particular question is that, of course, it's not normal policy issue. In terms of games, this is exactly the moment in the game where players start arguing about the rules of the game. And as any gamer knows, it's really hard to adjudicate the rules of a game in the middle of the game where one's interpretation of the rules is clearly influenced by one's position in this one particular game. This is why when it comes to games, we are very keen on having clear rules ahead of time. If possible, we would like to have an authority that would adjudicate any problem that might come and we think it's a design flaw if the game requires to consult such adjudication to often or is unclear on many issues.
But of course, we have no choice in life but to have such arguments about the rules of the political game. We have to set the boundaries of democratic units and we have to do it in a way that would itself be regulated by the rules of democracy. This is why this referendum is a huge step forward in many ways and a tremendous historical precedent for any group of people in the world that feel like they are disenfranchised. You can win the state of having your own voice through a democratic process! it shouts. But since we want to have the process of setting boundaries a democratic one, we want it too to be an ongoing one with the option to test different setups, to change our minds, to have an ongoing discussion and debate about it. Which is why I have reservations about the referendum and particularly about a Yes vote, and would much rather see an increase in Scottish independence within the union - allowing people to take part in more rather than less decision-making processes, having more decision-making forums (or fora), not less. That's especially true given how little we know, and how much we need to speculate, about the consequences of a Yes vote. That's my qualified and tentative argument against independence.
Whatever happens today, it's a pretty remarkable day for anybody who is interested in politics. That this kind of momentous decision can take place in such relative peace is an incredible achievement, which means whatever way the vote goes: It's an historic win for democratic ideas and non-violent resolution of conflicts. Good job, Scotland!