Constitutional commissions for Scotland are suddenly in fashion. In the past 10 days, three leading politicians - Wendy Alexander, Chris Huhne and Annabel Goldie - have called for some kind of commission to be set up. They are not alone. Iain Macwhirter and David Steel have been calling for a new Constitutional Convention for some time now. The problem is that they all want different things, and for different reasons.

Constitutional commissions for Scotland are suddenly in fashion. In the past 10 days, three leading politicians - Wendy Alexander, Chris Huhne and Annabel Goldie - have called for some kind of commission to be set up. They are not alone. Iain Macwhirter and David Steel have been calling for a new Constitutional Convention for some time now. The problem is that they all want different things, and for different reasons.

Although they might deny it, each of them seems to have particular outcomes in mind. It is significant that none of them is calling for a constitutional commission to do what is most needed at this moment in Scotland: make a fundamental, apolitical appraisal of the constitutional and other implications of all the relationships between Scotland and the other countries of the UK, ranging from more devolution, through forms of federation and confederation, to full independence.

As it happens, such a commission already exists. The Constitutional Commission was set up last year by a group of concerned citizens. The commission's members and supporters include Canon Kenyon Wright, Baroness Helena Kennedy, Professor Phil Hanlon, John Drummond, Sir Bernard Crick, Neal Acherson, Alan Smart, William McIlvanney, John McAllion, myself and others. The commission differs from others being proposed, in a number of respects.

First, it is not tied to any political agenda and is not wedded to any particular outcome. This is a great advantage because it allows the commission to consider all constitutional options, and to explore the implications of each. We see no sign that other commissions or conventions being called for would look objectively at all options. One way or another, each of them is restricted to a particular view of the world.

Secondly, we take as our starting point the belief that the doctrine of the "absolute sovereignty of parliament" has never applied in Scotland. In Scotland, sovereignty resides with the people and this principle was formally confirmed in 1995 when some prominent Scots put their names to the Constitutional Convention's Claim of Right, which affirmed "the sovereign right of the people of Scotland to determine how they will be governed". That claim and those signatures (including the majority of Scotland's Westminster MPs) effectively denied the right of Westminster to absolute sovereignty. This is important when we recall that just a few years ago the Scottish people were led to war against their will.

Thirdly, we believe any changes to Scotland's constitutional relationships with the rest of the UK should be fully discussed and decided within Scotland. These discussions should, of course, be in consultation with the rest of the UK, but the decision about Scotland's future should take place wholly within Scotland. It is important to make this point because there are still those who believe Scotland's constitutional future should be decided outside Scotland.

Fourthly, Scotland's future should be decided by its people. The Power Inquiry highlighted how much power has been taken from the people. The early promise of a "participative democracy" in Scotland after devolution has not been fulfilled. There is a need to debate the distribution and exercise of power. That is a debate about Scotland's constitution.

Chris Thomson, Calle Caspe 45 (2/1), Barcelona.

We welcome Wendy Alexander's recognition of the need to re-examine Scotland's constitutional position. However, such a commission or convention must be not only independent, but inclusive of civil society and the political spectrum, not just Unionist parties. It should have an open remit for admitting and exploring the possibilities of all outcomes, from continued union, through varying forms of federal status and association, to independence. It must be open and transparent and recognise that constitutional change requires a referendum.

We formed the Constitutional Commission this year for this purpose (www.constitutionalcommisssion.org). It includes constitutional thinkers as well as grass-roots organisations, from NGOs to business, faith and other groups. The people of Scotland need one inclusive Constitutional Commission, not a Unionist v Nationalist old-fashioned political-party confrontation; and we are delighted that your editorial endorses this view.

Canon Kenyon Wright and John Drummond, Hatchback House, Kinross.