The social justice competition

Both are party leaders. Both are offering "social justice" as a key objective.

However, Ed Miliband and Alex Salmond reach rather different conclusions as to the best way to deliver that aim.

From the outset, the fundamental independence offer has been a blend of prosperity and fairness.

Much of the debate, understandably, has focused upon the former: upon the prospects for enhancing Scotland's economy.

Today the focus was very much upon the latter, upon a search for ensuring that resources are more equitably distributed.

This reflects, of course, a contest for support from those who currently have relatively little: those who have tended to vote Labour in the past, if they vote at all.

Egalitarian approach

Firstly, it is worth noting that it is taken as a given by both Ed Miliband and Alex Salmond that the preponderance of opinion in Scotland favours redistribution, favours an egalitarian or communitarian approach.

Set aside for now the issue of whether any different calculation would be made with regard to voters elsewhere in the UK.

Focusing on Scotland, both presume that an egalitarian approach is likely to be relatively, if not universally, popular. They presume a communitarian outlook.

Further, they presume that a redistributive approach, pitched primarily at the less economically favoured would be endorsed or at least tolerated by the remainder of the population: that it would win general favour.

Alex Salmond and Nicola Sturgeon have marked a decade as leader and deputy leader of the SNP

Therefore, they are offering the same fundamental philosophy to the same potential electorate: the relatively dispossessed and those who would wish to see a more equal distribution of resources.

It is at this point that the offers diverge.

Alex Salmond says that social justice is most obviously and consistently attained via independence.

He argues that, with full economic powers, an independent Scottish Parliament would be able to effect change in line with the communitarian outlook which he believes the Scottish people espouse.

Mr Salmond argues, further, that such an objective could be thwarted, as in the past, if Scotland's governance continues to involve a UK administration which may not reflect Scottish choices.

'Redistributive clout'

In essence, Mr Miliband argues for the redistributive clout of the UK - but, crucially, only with the election of a Labour UK government.

He argues that independence would restrict the capacity to implement redistribution on the claimed basis that the newly independent state would struggle to sustain public spending.

Further, he targets the SNP directly, noting their support for a cut of up to 3p in corporation tax and their scepticism (he puts it rather more strongly) about Labour policies such as an energy price freeze and a restored 50p income tax rate.

In response to that, Mr Salmond says that the corporation tax cut, over a period, is designed to enhance the economy and thus enable redistribution and social justice.

On the other points, Mr Salmond there is doubt about the practicality of the energy price freeze: would there be a hike in advance to offset it?

On the 50p rate, he says the SNP opposed its removal in the first place and would not reverse it if it is re-introduced by a UK Labour government.

Ed Miliband has argued only a UK Labour government can deliver social justice

'More fundamental'

But Mr Salmond makes a further point. He says that the argument is not about Labour or SNP policies, not about Ed Miliband or Alex Salmond.

It is, he says, more fundamental. It is, once again, that decisions affecting Scotland should properly be taken by the people who live here.

To which Mr Miliband says that Labour favours further powers for Holyrood - but not to an extent that it would generate what he calls a "race to the bottom" over tax within these islands.

Amid it all is the customary rhetoric.

"You're in bed with the Tories!"

"No, you are!"

This is not to be entirely discounted: it is still a facet in winning Scottish opinion, despite all the Conservative attempts to obtain parole from their long sentence of political banishment seemingly decreed by the people of Scotland.

But, more basically, it is about two competing interpretations of a single aim.