Those making the case for Scotland to remain part of the United Kingdom have had the better of the argument in the past 10 days, since George Osborne, the Chancellor, delivered his speech opposing a currency union.

The Government hopes to press home the advantage with this week's meeting of the Cabinet in Aberdeen: a symbolic affirmation of the Union.

Constitutional purists will splutter about the use of the Cabinet as a travelling circus, the further relegation of the supreme collective decision-making body to a ceremonial photo-opportunity. Pragmatists will note that flexibility, innovation and gradual change has always been the genius of the British constitution. They will note that the Cabinet ceased to be a forum for live policy debate in Margaret Thatcher's time, and that it was Gordon Brown who started holding occasional meetings outside London for symbolic purposes. Efficient government demands that decisions are taken in smaller groups and Cabinet subcommittees, reserving full Cabinet for final approval or crises, while there is nothing wrong with a little symbolism – and it does Cabinet ministers good to be reminded of the country outside the capital.

That is also why it was right for the Chancellor to go to Edinburgh to deliver his speech on the future of the pound if Scotland should become an independent country. It was a serious speech about a serious question, and it was, rightly, delivered in a matter-of-fact style without rhetoric or party politics. In an unusual display of cross-party unity, his argument was supported by Ed Balls, the shadow Chancellor, and Danny Alexander, the Liberal Democrat Chief Secretary to the Treasury. In an even more unusual display of civil service engagement in public controversy, it was also supported by Sir Nicholas Macpherson, the Permanent Secretary to the Treasury.

So far, the response of the Scottish National Party has been disappointing. Alex Salmond, Scotland's First Minister, accused the forces united against him of bullying. He is quite right, of course: the way in which Westminster ranks closed was choreographed to intimidate and disconcert that section of Scottish opinion that is worried about the uncertainty of a big change. But the argument against a currency union requires a more persuasive response than a complaint that the other side is trying to win.

Indeed, Mr Salmond needs a better case than the one counter-argument he has advanced so far, which is that, if Scotland votes for independence, the government of the rest of the UK would change its tune and negotiate a currency union after all. That is a risk that hesitant nationalists might be unwilling to take. Mr Salmond needs to spell out a back-up plan.

If an independent Scotland fails to negotiate a currency union with London, it could create its own pound in the way that Ireland did in 1978. But these are options that need to be set out in detail and with rigour – a quality that too much of the Scottish government's white paper on independence lacked.

The unionists have started to defend what they believe in with some force – and to come to Scotland to do it – but also with serious argument that respects Scotland's right to make its decision.

The SNP needs to respond, over the next seven months, with the same commitment, confidence and attention to detail. There is a better case for independence than claiming victim status.