As Labour have closed what seemed like an unbridgeable gap in the polls with the SNP, a loch of ink has been spilt speculating about the extent to which the constitutional question matters anymore.

The logic is clear – independence is fading into the political background as kitchen table issues come to the fore. When voters are worried about paying the rent or mortgage and putting food on the table, what mental space do they have to dedicate to such supposedly esoteric concerns as the constitution?

But this is incredibly simplistic. The importance of the constitution in voters’ minds has not decreased as the gap between the SNP and Labour has closed. In December last year, an Ipsos poll had the SNP sitting on 51% of the vote in a hypothetical Westminster election. In the same poll, 23% mentioned the constitution when asked about the most important issues facing Scotland.

In May, another Ipsos poll showed the SNP on 41% of the vote, with 25% mentioning the constitution as one of the country’s most important issues. This finding is consistent across several polls.

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The change that has taken place is more subtle. Independence has not become less important to its supporters. Rather, they believe it has become significantly less likely to happen. Most Scots do not believe there will be an independence referendum any time soon, and if there were a referendum, more Scots think that No would win rather than Yes. In polling by Redfield and Wilton last November, the opposite was true.

As a result, such voters have begun considering alternatives. They have done so against the background of an ongoing scandal around the SNP’s finances which, even if it does not result in charges being brought against any of that story’s protagonists, has exposed the small clique that has run the party for over a decade and highlighted their tendency for mismanagement.

So, it is no surprise that Labour, the only other major party in a position to put forward a change agenda that Scottish voters might entertain, is benefitting in the polls. But the fundamental motivation of those voters has not changed – they perceive a broken society and are willing to vote for radical action to fix it.

Of course, this isn’t about the constitution in its own right – our governing arrangements are means to ends. No, the issue at the heart of Scotland’s movement towards political change is a far more fundamental problem: a crisis of political legitimacy.

When political scientists talk about legitimacy, we are talking about the public’s acceptance of the authority of a regime – the form and rules, written and unwritten, of government.

In a liberal democracy like the United Kingdom, the legitimacy of the ruling regime is ultimately anchored in what the German sociologist Max Weber called rational-legal legitimacy: public trust that governing institutions will govern in the public’s interest.

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We can assess how well a governing regime derives such legitimacy. Professor Fritz Scharpf, a German political scientist, identified two ways regimes do so: input legitimacy and output legitimacy.

Output legitimacy refers to the effectiveness of policy outcomes for the public; in other words, the ability of government to get things done and improve people’s living standards. Input legitimacy refers to how responsive government is to citizens’ concerns and the extent to which people can affect decision-making.

And in both areas, the legitimacy of Scotland’s governing regime has come unmoored.

On the output side, this is reflected in the thin ledger that is Nicola Sturgeon’s policy legacy after eight years as First Minister, not as a consequence of her ability as much as it is of the apparent incapability of government in Scotland to get anything significant done.

At Westminster, ever since the 2008 financial crisis, the only policies government has been able to implement have been those that have impoverished Scots (and Brits as a whole).

And at the local government level, public services have consistently deteriorated, often vanishing completely.

The input side is hardly healthier. Scots feel completely disconnected from Westminster, with few sensing a capacity to shape decision-making there.

Opponents of independence often shrug off the SNP’s argument that Scotland has been ruled for most of the post-war period by Tory governments it did not vote for. They find convenient excuses to dismiss their point that Scots had Brexit imposed upon them against their will.

But the reality is that these arguments are fundamentally correct – and it amounts to burying one’s head in the sand to pretend that they are not.

And Holyrood increasingly suffers from that sense of disconnection, as the recent battle over Highly Protected Marine Areas demonstrates. Many Scots, particularly outwith the central belt, feel about as well-represented in Edinburgh as they do in London.

Scotland is in the midst of a legitimacy crisis and is not alone. Underlying government failures are fundamental crises like climate breakdown and an ageing population. In many ways, we are lucky – elsewhere in Europe, this kind of legitimacy crisis has fuelled the rise of the far-right, the erosion of the cordon sanitaire between the centre-right and the far-right, and in some cases, the entry of fascism’s successors into government.

The widespread nature of this crisis does not give Scotland’s governing parties an excuse to wash their hands of it. Labour are not rising in the polls because the constitution has become less of a concern to voters but because those who support independence are looking for a short-term alternative solution to Scotland’s legitimacy crisis.

It’s a thorny problem. If Labour do not want their newfound support to melt away, they must come up with that alternative solution. That is one thing, a question of political messaging. But it is difficult to see what the actual solutions are.

Nevertheless, whomever is in government at Westminster and Holyrood over the next decade will need to wrestle with this crisis. Failure to do so will be catastrophic for our politics – there are, after all, worse forces than civic nationalism.