Optimism is a fine thing - except when it leads to delusion. A Labour MSP was complaining privately last week about the media's lack of faith in the Scottish party's leadership contest.

His view was that we had all got it hopelessly wrong. Instead of dismissing it as a contest of three relative lightweights that would do nothing to restore Labour's fortunes at Holyrood, we would all do well, he argued, to remember the summer of 2004 when the Scottish National Party was in a similar position.

John Swinney had just resigned after a rebuff from Scottish voters in the European Parliament elections and post-devolution power for the Nationalists appeared farther away than ever. “Look at the SNP now,” appeared to be the Labour MSP's view, the implication being that the same sort of remarkable transformation could happen to Scottish Labour.

He was right - up to a point. The SNP had appeared to be down and, if not out, heading for nothing more than permanent opposition at Holyrood. That's where the comparison begins to crumble.

For Labour has no one to call on of the opportunistic calibre of Alex Salmond (even if Mr Salmond did stand in 2004 as the “Stop Roseanna Cunningham” candidate). His achievement was to reposition his party, making it appear populist and vibrant compared with a Labour Party that was increasingly moribund in Scotland.

Mr Salmond also used his plentiful powers of persuasion to convince well-heeled backers to part with sizeable amounts of cash and, crucially, he was able to exploit the disarray of an increasingly unpopular Labour Government at Westminster. The SNP won because, unlike Labour, it had something new to say to Scottish voters.

Thus far in this Labour leadership debate there has been much fine talk about how Labour in Scotland can also go about reviving itself, much of it centred on a farcical argument about future relations between Labour at Holyrood and Labour at Westminster.

It should be obvious to even the most Westminster-fixated MP that if you set up a Parliament in Edinburgh you must be prepared to let the politicians there make their own day-to-day policy judgments, even if they might occasionally contradict your own. It's called political reality.

All three candidates - Iain Gray, Cathy Jamieson and Andy Kerr - have been busying themselves making all sorts of policy promises as if they were still in government - but all three have apparently ignored the bigger and much more important picture.

That bigger picture involves articulating an argument for the Union that can be presented as a viable alternative to Mr Salmond's notion of a “milk-and-honey” independent Scotland.

That all three seem unable or unwilling to do this, is extraordinary: one does not have to resort to past scaremongering of the “going to Hell in an independence handcart” sort, beloved of such as John Reid and Douglas Alexander, to justify the continuing value of the Union to Scotland and the Scots.

This is especially true at a time when Nationalists, and their disciples in the Scottish media, are having a tough time coping with the sense of identification and pleasure that the British success at the Beijing Olympics has stirred in many Scots.

While it would be ludicrous to suggest that Rebecca Adlington may yet turn out to be the saviour of the Union, the likes of Chris Hoy have shown that, despite Nationalist prejudices to the contrary, there is nothing sad or perverse in feeling both Scottish and British.

But the awakening of notions of shared British experience and shared British interests appears to have passed Messrs Kerr, Gray and Jamieson by. They have absolutely nothing to say on the subject.

Once again, when it comes to letting the case for the Union go by default, Labour in Scotland takes the gold medal.

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