It was a bright spring day as well-kent faces from a variety of political backgrounds came together in Edinburgh to sign a declaration affirming Scotland's right to make its own decisions in its own way.

No, not the SNP's Yes to Independence campaign on Friday, but the Claim of Right Declaration of Sovereignty in 1989. I've been knocking around Scottish politics longer than is good for me, and I couldn't help comparing the text of the SNP's declaration with the one I saw signed back in the day.

Friday's Declaration of Independence read as follows: "I believe that it is fundamentally better for us all if decisions about Scotland's future are taken by the people who care most about Scotland, that is by the people of Scotland."

Roll back nearly a quarter of a century and the Claim of Right affirmed "the sovereign right of the Scottish people to determine the form of government best suited to their needs and [the undersigned] do hereby declare and pledge that in all our actions their interests shall be paramount".

No, they're not identical – the language is different, but the spirit is very much the same. They are both assertions of the sovereign right of a people to determine their future. And it is quite difficult to disagree with either proposition. Though, of course, the SNP did boycott the Claim of Right, which was signed by all of Labour's Scottish MPs except for Tam Dalyell.

The former, of course, says that "all decisions" should be taken in Scotland by Scots, but not even the SNP believes that is possible any more. Under their plan for independence the Bank of England would still be taking some of the most important decisions of all – interest rates and monetary policy. Then there are all those decisions that are taken in Brussels by the European Union, which, if it survives, may by 2014 be a federal body imposing common fiscal policies across European countries. No nation is an island any more and self-determination is very much diminished by international treaties and economic relations.

I'm not just trying to make clever debating points here. Lots of people who do not believe in independence could sign the SNP's declaration, just as Unionists could sign the Claim of Right. I agree that all decisions should be taken where possible in Scotland by Scots. But this does not mean I'm a signed and sealed Nationalist. Many decisions will still have to be taken jointly with England and this implies, to me, a form of federalism.

The Nationalists seem fairly relaxed about this – they say they want to create a network of support that goes beyond party and is rooted in the community. Fair enough. But if everyone is allowed into this broad church, isn't there a risk that it will mean all things to all men?

The SNP is not proposing to put together a draft constitution for an independent Scotland.

The SNP say that it will be up to the government elected to Holyrood in 2016 to decide what independence is going to look like in practice. The SNP confidently expect it will be them, but what if a non-nationalist coalition wins that election? What exactly would an incoming Labour-Liberal Democrat coalition Holyrood in 2016 make of it all?

Well, based on the Independence Declaration, First Minister Johann Lamont might say: "The referendum commits us to nothing specific – like the Claim of Right, it is vague. Scotland is already nation with its own parliament, all parties agree on keeping the Monarchy and the pound. We believe the Scottish people wish to see maximum possible economic powers devolved to Holyrood. We call this 'Independence in the UK', as it was once so described by Donald Dewar."

Perhaps Labour should be launching a "Unionists for Independence" campaign next week.