The standard assumption about political debates is that the campaign with most to gain in all in favour of them while the candidate presumed to be the front-runner wants nothing to do with them. Franklin Roosevelt refused to debate Wendell Wilkie in 1940, LBJ refused to debate Barry Goldwater in 1964 and, four years later, Richard Nixon (perhaps recalling his experience in 1960) declined to debate Hubert Humphrey. Indeed, you can argue that the modern American practice of Presidential debates might not exist at all but for the weakness of the position in which Gerald Ford found himself in 1976.

As matters stand, I suspect there will be some reluctance to repeat 2010′s experiment with televised debates between the three principle party leaders. David Cameron will not be inclined to grant Ed Miliband an opportunity to appear Prime Ministerial (whatever that means) though, notionally, a series of debates would, assuming the Lib Dem leader is included, give the government 66% of the airtime to defend its record.

Nevertheless there is, I think, a sense that the 2010 debates distorted the campaign. It was three debates and not much else with the media either previewing or reviewing the debates and largely ignoring all the lovely scripted moments the campaigns had planned for their consumption.

But what about the other campaign Mr Cameron faces? Well, it seems he won’t be debating Alex Salmond either. Downing Street suggests that Salmond’s challenge to debate Cameron is the kind of “wheeze” for which the Prime Minister will not fall.

Doubtless there are decent reasons for declining the opportunity to wrestle with Salmond. It certainly suits the First Minister to suggest Cameron is feart. According to Annabelle Ewing “quoted” in an SNP press release, the Prime Minister’s disinclination to debate Salmond “speaks volumes about the UK Government’s attitude to Scotland”.

Perhaps it does, though of course one reason the SNP want a Salmond-Cameron debate is that pictures of Salmond an Cameron debating one another elevate the First Minister’s status while subtly reducing Cameron’s. The nationalist expectation is that Salmond would be seen as Scotia’s champion while Cameron may be regarded as the (Tory) leader of some kind of foreign power.

So, in that respect, Cameron’s reluctance to play this game is understandable. And yet, damn it, there’s something mildly regrettable about it too. True, Cameron did not perform particularly well in the 2010 election debates (I thought he only won one of them) but that’s an ignoble (if practical) reason for avoiding them in the future.

And since the Prime Minister really does believe in the Union there is something to be said for him making that case in a debate (or series of debates!) against Alex Salmond. I think it would be useful for Scots to hear from the Prime Minister just why they are a valued part of the British polity. Most of all, however, there’s something odd about the Prime Minister excusing himself from the field of battle when that battle is a fight for the future existence of his own country.

Nevertheless, it is also the case that the other reason the SNP are so keen to have a Salmond-Cameron debate is because, deep-down, leading nationalists worry they are, as matters stand, on course to lose this referendum. Which, of course, is another reason why Cameron feels no need to risk debating Alex Salmond.

Tags: Alex Salmond, british politics, David Cameron, Debating, Scottish independence, Unionism