Not much happens in a devolved Scotland without a commission.

Some of the great and good have sacrificed large parts of their lives to these august bodies. They are one-stop shops for people who like to talk.

That doesn't mean commissions are a bad thing necessarily. At their best they give formal expression to decent ideas. They draw on expertise and experience. The obligation to come up with a report and stand by it concentrates minds. But often enough the things examined by commissions seem to include navels.

Party conferences, such as they are these days, are more or less circumvented. Commission terms of reference, set by party leaderships, have a tendency to produce desired outcomes. Wider consultations, if they occur, often smack of tokenism. Commissions might appear only to make recommendations. In reality, they set agendas. In practical terms, they hobble democracy.

Despite (or because) of that, each of the parties involved in the Better Together referendum campaign has a commission on the go. The reason is simple. Labour, the Tories and the Liberal Democrats are under growing pressure to explain what happens, if anything, in the event of a No vote on September 18. Each party is struggling, if not floundering, in the attempt to produce answers.

The excuse that the referendum is designed to settle the question of independence, and that nothing else need be discussed, has worn paper thin. It's about as plausible as the claim that David Cameron, Prime Minister of the United Kingdom, has no duty to meet Alex Salmond in public debate. The three parties are being challenged to get to the heart of the matter: what does Better Together really mean?

Hence, variously, Labour's Lamont (or Devolution) Commission, the Strathclyde Commission from the Tories, and the Lib Dems' Campbell Commission (Mark II). The airy assurance of "more powers" of an unspecified nature at some unspecified point in the future was always a bit of an insult. Now it's untenable. Silence is not an option.

The Scottish National Party has made its offer at length in its white paper. On Monday, meanwhile, the Financial Times commenced a week of articles on independence with an analysis that left the No campaign struggling for a rebuttal. The FT, internationally respected journal of business and economics, told exactly the story Yes Scotland wanted to hear.

Given its share of oil and gas, GDP per head in Scotland is bigger than that of France. Even without "the North Sea's hydrocarbon bounty" per capita GDP is higher than that of Italy. Given independence, we would rank among the world's top 35 exporters. "Subsidised Scotland", "the £500 question", oil price volatility: the FT analysis settled these matters. It also left the reader, partisan or undecided, to wonder why a remaining UK would refuse a currency union with a prosperous, export-led neighbour.

So the onus falls on No. If people are being pressed hard by Better Together to think about what they might be voting for, they are entitled to ask about the alternatives. It's what's known as an informed choice. And here things become murky.

Vague hopes that the Unionist parties might arrive at a common position look forlorn. True, there are genuine differences between them. For future electoral purposes there is also, so the parties hope, the issue of "differentiation". It wouldn't do to approach UK and Scottish elections with each of them offering exactly the same thing to Scotland.

But the Better Together allies also have to deal with the suspicion that all the promises of "more powers" amount to a shabby ruse. Older Yes campaigners have never forgotten the pledge made by Alec Douglas-Home in 1979 and broken by the Conservative Party that a vote against limited devolution in that year's referendum would lead to a better deal. Last year's volte face by Ruth Davidson, erasing her "line in the sand" over more powers for Holyrood, was therefore greeted with scepticism.

Tory attitudes towards devolution have never been afflicted with consistency. The Scottish wing is in any case saddled with a regiment of English colleagues who despise the whole notion and who are more worried about Ukip or Europe than events north of the Border. If they think about Scotland at all they think about Labour's potential losses at Westminster. Those Tories are relaxed, let's say, about independence.

So the commission entrusted to the leadership of Lord Strathclyde has been a leisurely affair. Its interim report, expected last autumn, failed to materialise. Such conclusions as it might have reached should surface at next month's Scottish annual conference if the party is to avoid ridicule. For now, all we know is that Ms Davidson aspires, as she said when launching the commission, to give the Edinburgh Parliament "more responsibility", some of it financial.

The Liberal Democrats have meanwhile gone back to the future, a century back, reviving the old federal dream of "home rule all round" with a commission led by Sir Menzies Campbell. Now the party means to extend the exercise by somehow pulling together strands of "the emerging consensus for building a stronger Scotland within the UK".

In a speech to the David Hume Institute yesterday, the party's Scottish leader, Willie Rennie, talked of "planning a timetable for implementing lasting, permanent constitutional change after the referendum" in addition to granting Holyrood control over personal and corporate taxation. But how do you manage "home rule all round" when England has so much of the population and economic power within any Union? There are reasons why federalism is an old, unrealised dream.

Labour meanwhile seems unable to decide what to offer. Johann Lamont's apparent hope that Holyrood might be given full control of income tax split the party last spring and is doing so again. This week, Ken Macintosh MSP let it be known that such a scheme would be "independence by default" and reduce the tax base. Ian Davidson, the Glasgow South West MP, has weighed in to claim that the Barnett formula would be lost. Other MPs, he said, were also concerned. Many fear "a loss of influence" (their own) at Westminster.

All of the Better Together parties need to win over undecided voters. In practice, that means convincing people who would otherwise support Labour. But the party preparing to make its offer at its Perth conference next month is deeply divided. How to choose? Cede too much and it cedes the argument over autonomy; fail to give ground and it will stand accused of bad faith.

The Calman Commission - another commission - was supposed to have produced the last word on these matters with the Scotland Act 2012. That legislation has become history long before its provisions for tax and borrowing powers are due to come into force. Like it or not, with sincerity or not, the Better Together trio are compelled to offer more. Or at least to seem to offer more.

Will fresh promises be believed? If believed, will they survive the turbulence of Westminster politics as a UK General Election approaches? What are promises worth when they are made under duress to a country told that it is as rich as France? Unionists have painted themselves into a tight corner.