There are many sensible arguments to be made for and against Scottish independence.
It is depressing that so much time has been spent on a non-argument: Scottish membership in the European Union.
If Scotland were to become independent, the rUK would still be a EU nation, and Scotland would have to apply for EU membership, UN recognition, and would have to ratify the various international charters, treaties, and laws. None of this would be automatic, but none of this would be difficult to accomplish.
From the conclusions of the Presidency, Copenhagen 21-22 June 1993 – the Copenhagen criteria:
The European Council today agreed that the associated countries in Central and Eastern Europe that so desire shall become members of the European Union. Accession will take place as soon as an associated country is able to assume the obligations of membership by satisfying the economic and political conditions required.
Membership requires that the candidate country has achieved stability of institutions guaranteeing democracy, the rule of law, human rights and respect for and protection of minorities, the existence of a functioning market economy as well as the capacity to cope with competitive pressure and market forces within the Union. Membership presupposes the candidate’s ability to take on the obligations of membership including adherence to the aims of political, economic and monetary union.The Union’s capacity to absorb new members, while maintaining the momentum of European integration, is also an important consideration in the general interest of both the Union and the candidate countries.
The European Council will continue to follow closely progress in each associated country towards fulfilling the conditions of accession to the Union and draw the appropriate conclusions.
Scotland as an independent nation fulfils the Copenhagen criteria: there are stable institutions guaranteeing democracy, the rule of law, human rights and respect for and protection of minorities; there is a functioning market economy capable of withstanding the pressure of competition and market forces in the European Union; there is the ability (just as rUK has the ability if not the political will) to assume all the obligations flowing from membership, including the aim of political, economic and monetary union.
In particular:
What comes closest to a catalogue of concrete requirements which must be met by applicant countries is the third criterion, according to which the countries must be in a position to implement all the EU’s laws and regulations.
Scotland is actually slightly ahead of the rest of the UK on this. Already. And considerably ahead of other countries which have been admitted into the EU even though they have not yet implemented all of the EU’s laws and regulations.
Assuming a Yes vote in 2014 (no one needs to tell me what a big assumption that is!) there would be a period of time – perhaps as little as 18 months, perhaps as much as five years – between the vote and independence day. During that time, among the tasks of preparation for Scotland as an independent state, would be to have EU membership applied for.
Arguments that perhaps the EU wouldn’t let Scotland become a member don’t really get started because the only plausible argument is: What if rUK tried to veto Scottish membership?
Ultimately, however, it is the [European Council] which decides on the accession of a country by unanimous decision after consultation with the Commission and after the assent of the European Parliament, which means that the European Parliament must approve the Council’s decision.
The Prime Minister of the UK is one member of the European Council. Certainly the PM – whether Cameron or Miliband or whoever – could speechify, vote, argue, call in favours, try to block Scotland from EU membership. UK MEPs and their allies in the European Parliament likewise.
But they wouldn’t. Because they know they’d lose the vote. There is no plausible argument that could convince other European heads of state. There is no huge gameplay that could swing the European Parliament to vote with the UK MEPs against Scottish membership. All that such politicking would accomplish would be to bring Scotland into the EU not as an obvious political ally but as a long-term foe.
So could we just drop the EU argument?
Update, April 2014: But see point 7.
Edinburgh Eye 
This is interesting. I agree that rUK wouldn’t stand in the way of Scotland joining the EU. I just think the consequences of that new membership (the Euro and, whatever the public’s pride hopes for, a much smaller, weaker voice) are too high a cost for not much gain. We already have a strong EU membership. If we should want to stay in it then why on earth would we dilute our membership?
It’s possible – not having a crystal ball – that if Scotland becomes independent, by the time independence day happens it will no longer seem advantageous to join the EU. At the moment, however, presuming a reasonably strong Scottish economy, it would be better to be part of the EU than outside it.
I’m no currency expert: the various currency options available to an independent Scotland would need to be seriously examined if the vote went Yes in 2014.
Plus, the significant day-to-day advantages of being in the EU, such as open borders, are not to be dismissed. Assuming Scotland goes indy and rUK stays in EU, then it’s to the obvious advantage of both countries for there to be an ordinary EU open border between Scotland and rUK, and for that matter Scotland and Ireland – no issues about trade, visitors, or work, no need to make any special legislative arrangements to ensure that.